General term for a number of inherited defects of amino acid metabolism in which there is a deficiency or absence of pigment in the eyes, skin, or hair.
Heterogeneous group of autosomal recessive disorders comprising at least four recognized types, all having in common varying degrees of hypopigmentation of the skin, hair, and eyes. The two most common are the tyrosinase-positive and tyrosinase-negative types.
An enzyme of the oxidoreductase class that catalyzes the reaction between L-tyrosine, L-dopa, and oxygen to yield L-dopa, dopaquinone, and water. It is a copper protein that acts also on catechols, catalyzing some of the same reactions as CATECHOL OXIDASE. EC
Syndrome characterized by the triad of oculocutaneous albinism (ALBINISM, OCULOCUTANEOUS); PLATELET STORAGE POOL DEFICIENCY; and lysosomal accumulation of ceroid lipofuscin.
Involuntary movements of the eye that are divided into two types, jerk and pendular. Jerk nystagmus has a slow phase in one direction followed by a corrective fast phase in the opposite direction, and is usually caused by central or peripheral vestibular dysfunction. Pendular nystagmus features oscillations that are of equal velocity in both directions and this condition is often associated with visual loss early in life. (Adams et al., Principles of Neurology, 6th ed, p272)
A condition caused by a deficiency or a loss of melanin pigmentation in the epidermis, also known as hypomelanosis. Hypopigmentation can be localized or generalized, and may result from genetic defects, trauma, inflammation, or infections.
The common orally transmitted traditions, myths, festivals, songs, superstitions, and stories of all peoples.
Melanin-containing organelles found in melanocytes and melanophores.
Nystagmus present at birth or caused by lesions sustained in utero or at the time of birth. It is usually pendular, and is associated with ALBINISM and conditions characterized by early loss of central vision. Inheritance patterns may be X-linked, autosomal dominant, or recessive. (Adams et al., Principles of Neurology, 6th ed, p275)
The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.
A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.
Color of the iris.
Mammalian pigment cells that produce MELANINS, pigments found mainly in the EPIDERMIS, but also in the eyes and the hair, by a process called melanogenesis. Coloration can be altered by the number of melanocytes or the amount of pigment produced and stored in the organelles called MELANOSOMES. The large non-mammalian melanin-containing cells are called MELANOPHORES.
Coloration or discoloration of a part by a pigment.
Albinism affecting the eye in which pigment of the hair and skin is normal or only slightly diluted. The classic type is X-linked (Nettleship-Falls), but an autosomal recessive form also exists. Ocular abnormalities may include reduced pigmentation of the iris, nystagmus, photophobia, strabismus, and decreased visual acuity.
Insoluble polymers of TYROSINE derivatives found in and causing darkness in skin (SKIN PIGMENTATION), hair, and feathers providing protection against SUNBURN induced by SUNLIGHT. CAROTENES contribute yellow and red coloration.
Autosomal dominant, congenital disorder characterized by localized hypomelanosis of the skin and hair. The most familiar feature is a white forelock presenting in 80 to 90 percent of the patients. The underlying defect is possibly related to the differentiation and migration of melanoblasts, as well as to defective development of the neural crest (neurocristopathy). Piebaldism may be closely related to WAARDENBURG SYNDROME.
Infection caused by the protozoan parasite TOXOPLASMA in which there is extensive connective tissue proliferation, the retina surrounding the lesions remains normal, and the ocular media remain clear. Chorioretinitis may be associated with all forms of toxoplasmosis, but is usually a late sequel of congenital toxoplasmosis. The severe ocular lesions in infants may lead to blindness.
Pigmentation disorders are conditions that affect the production or distribution of melanin, the pigment responsible for skin, hair, and eye color, leading to changes in the color of these bodily features.
The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.
'Eye proteins' are structural or functional proteins, such as crystallins, opsins, and collagens, located in various parts of the eye, including the cornea, lens, retina, and aqueous humor, that contribute to maintaining transparency, refractive power, phototransduction, and overall integrity of the visual system.
Abnormal sensitivity to light. This may occur as a manifestation of EYE DISEASES; MIGRAINE; SUBARACHNOID HEMORRHAGE; MENINGITIS; and other disorders. Photophobia may also occur in association with DEPRESSION and other MENTAL DISORDERS.
Coloration of the skin.
A form of phagocyte bactericidal dysfunction characterized by unusual oculocutaneous albinism, high incidence of lymphoreticular neoplasms, and recurrent pyogenic infections. In many cell types, abnormal lysosomes are present leading to defective pigment distribution and abnormal neutrophil functions. The disease is transmitted by autosomal recessive inheritance and a similar disorder occurs in the beige mouse, the Aleutian mink, and albino Hereford cattle.
Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.
Recording of nystagmus based on changes in the electrical field surrounding the eye produced by the difference in potential between the cornea and the retina.
Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.
The functional superiority and preferential use of one eye over the other. The term is usually applied to superiority in sighting (VISUAL PERCEPTION) or motor task but not difference in VISUAL ACUITY or dysfunction of one of the eyes. Ocular dominance can be modified by visual input and NEUROTROPHIC FACTORS.
Genetic diseases that are linked to gene mutations on the X CHROMOSOME in humans (X CHROMOSOME, HUMAN) or the X CHROMOSOME in other species. Included here are animal models of human X-linked diseases.
Measurement of ocular tension (INTRAOCULAR PRESSURE) with a tonometer. (Cline, et al., Dictionary of Visual Science, 4th ed)
A plant family of the order Liliales, subclass Liliidae, class Liliopsida (monocotyledons). Most species are perennials, native primarily to tropical America. They have creeping rootstocks, fibrous roots, and leaves in clusters at the base of the plant or borne on branched stems. The fruit is a capsule containing many seeds, or a one-seeded winged structure.
Refraction of LIGHT effected by the media of the EYE.
The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.
The concave interior of the eye, consisting of the retina, the choroid, the sclera, the optic disk, and blood vessels, seen by means of the ophthalmoscope. (Cline et al., Dictionary of Visual Science, 4th ed)
The most anterior portion of the uveal layer, separating the anterior chamber from the posterior. It consists of two layers - the stroma and the pigmented epithelium. Color of the iris depends on the amount of melanin in the stroma on reflection from the pigmented epithelium.
Tumors or cancer of the EYE.
A family of fresh water fish in the order CHARACIFORMES, which includes the Tetras.
The state of estrangement individuals feel in cultural settings that they view as foreign, unpredictable, or unacceptable.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
An enzyme of the oxidoreductase class that catalyzes the reaction between catechol and oxygen to yield benzoquinone and water. It is a complex of copper-containing proteins that acts also on a variety of substituted catechols. EC
Disorders that feature impairment of eye movements as a primary manifestation of disease. These conditions may be divided into infranuclear, nuclear, and supranuclear disorders. Diseases of the eye muscles or oculomotor cranial nerves (III, IV, and VI) are considered infranuclear. Nuclear disorders are caused by disease of the oculomotor, trochlear, or abducens nuclei in the BRAIN STEM. Supranuclear disorders are produced by dysfunction of higher order sensory and motor systems that control eye movements, including neural networks in the CEREBRAL CORTEX; BASAL GANGLIA; CEREBELLUM; and BRAIN STEM. Ocular torticollis refers to a head tilt that is caused by an ocular misalignment. Opsoclonus refers to rapid, conjugate oscillations of the eyes in multiple directions, which may occur as a parainfectious or paraneoplastic condition (e.g., OPSOCLONUS-MYOCLONUS SYNDROME). (Adams et al., Principles of Neurology, 6th ed, p240)
The layer of pigment-containing epithelial cells in the RETINA; the CILIARY BODY; and the IRIS in the eye.
Geological formations consisting of underground enclosures with access from the surface.
A heterogeneous group of bone dysplasias, the common character of which is stippling of the epiphyses in infancy. The group includes a severe autosomal recessive form (CHONDRODYSPLASIA PUNCTATA, RHIZOMELIC), an autosomal dominant form (Conradi-Hunermann syndrome), and a milder X-linked form. Metabolic defects associated with impaired peroxisomes are present only in the rhizomelic form.
The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)
Processes and properties of the EYE as a whole or of any of its parts.
An area approximately 1.5 millimeters in diameter within the macula lutea where the retina thins out greatly because of the oblique shifting of all layers except the pigment epithelium layer. It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. In its center (foveola) are the cones most adapted to yield high visual acuity, each cone being connected to only one ganglion cell. (Cline et al., Dictionary of Visual Science, 4th ed)
Damage or trauma inflicted to the eye by external means. The concept includes both surface injuries and intraocular injuries.
Color of hair or fur.
Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.
The X-shaped structure formed by the meeting of the two optic nerves. At the optic chiasm the fibers from the medial part of each retina cross to project to the other side of the brain while the lateral retinal fibers continue on the same side. As a result each half of the brain receives information about the contralateral visual field from both eyes.
The pressure of the fluids in the eye.
Tuberculous infection of the eye, primarily the iris, ciliary body, and choroid.
Glycoproteins found on the membrane or surface of cells.
The fluid secreted by the lacrimal glands. This fluid moistens the CONJUNCTIVA and CORNEA.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
Misalignment of the visual axes of the eyes. In comitant strabismus the degree of ocular misalignment does not vary with the direction of gaze. In noncomitant strabismus the degree of misalignment varies depending on direction of gaze or which eye is fixating on the target. (Miller, Walsh & Hoyt's Clinical Neuro-Ophthalmology, 4th ed, p641)
Diseases, dysfunctions, or disorders of or located in the iris.
Sterile solutions that are intended for instillation into the eye. It does not include solutions for cleaning eyeglasses or CONTACT LENS SOLUTIONS.
Disorder characterized by a decrease or lack of platelet dense bodies in which the releasable pool of adenine nucleotides and 5HT are normally stored.
Any of several generalized skin disorders characterized by dryness, roughness, and scaliness, due to hypertrophy of the stratum corneum epidermis. Most are genetic, but some are acquired, developing in association with other systemic disease or genetic syndrome.
A genetically heterogeneous disorder caused by hypothalamic GNRH deficiency and OLFACTORY NERVE defects. It is characterized by congenital HYPOGONADOTROPIC HYPOGONADISM and ANOSMIA, possibly with additional midline defects. It can be transmitted as an X-linked (GENETIC DISEASES, X-LINKED), an autosomal dominant, or an autosomal recessive trait.
A republic in western Africa, south of SENEGAL and MALI, east of GUINEA-BISSAU. Its capital is Conakry.
Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract.
The 2nd cranial nerve which conveys visual information from the RETINA to the brain. The nerve carries the axons of the RETINAL GANGLION CELLS which sort at the OPTIC CHIASM and continue via the OPTIC TRACTS to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the SUPERIOR COLLICULI and the SUPRACHIASMATIC NUCLEI. Though known as the second cranial nerve, it is considered part of the CENTRAL NERVOUS SYSTEM.
The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.
An autosomal dominant disorder caused by deletion of the proximal long arm of the paternal chromosome 15 (15q11-q13) or by inheritance of both of the pair of chromosomes 15 from the mother (UNIPARENTAL DISOMY) which are imprinted (GENETIC IMPRINTING) and hence silenced. Clinical manifestations include MENTAL RETARDATION; MUSCULAR HYPOTONIA; HYPERPHAGIA; OBESITY; short stature; HYPOGONADISM; STRABISMUS; and HYPERSOMNOLENCE. (Menkes, Textbook of Child Neurology, 5th ed, p229)
Mild to severe infections of the eye and its adjacent structures (adnexa) by adult or larval protozoan or metazoan parasites.
An island in the Greater Antilles in the West Indies. Its capital is San Juan. It is a self-governing commonwealth in union with the United States. It was discovered by Columbus in 1493 but no colonization was attempted until 1508. It belonged to Spain until ceded to the United States in 1898. It became a commonwealth with autonomy in internal affairs in 1952. Columbus named the island San Juan for St. John's Day, the Monday he arrived, and the bay Puerto Rico, rich harbor. The island became Puerto Rico officially in 1932. (From Webster's New Geographical Dictionary, 1988, p987 & Room, Brewer's Dictionary of Names, 1992, p436)
A melanocortin receptor subtype found primarily in MELANOCYTES. It shows specificity for ALPHA-MSH and ADRENOCORTICOTROPIC HORMONE. Loss of function mutations of the type 1 melanocortin receptor account for the majority of red hair and fair skin recessive traits in human.
Genes that influence the PHENOTYPE only in the homozygous state.
Conjunctival diseases refer to a broad range of disorders that affect the conjunctiva, the mucous membrane covering the inner surface of the eyelids and the outer layer of the eyeball, causing symptoms such as redness, itching, irritation, discharge, and/or inflammation.
Infection, moderate to severe, caused by bacteria, fungi, or viruses, which occurs either on the external surface of the eye or intraocularly with probable inflammation, visual impairment, or blindness.
Inflammation of part or all of the uvea, the middle (vascular) tunic of the eye, and commonly involving the other tunics (sclera and cornea, and the retina). (Dorland, 27th ed)
Chromatophores (large pigment cells of fish, amphibia, reptiles and many invertebrates) which contain melanin. Short term color changes are brought about by an active redistribution of the melanophores pigment containing organelles (MELANOSOMES). Mammals do not have melanophores; however they have retained smaller pigment cells known as MELANOCYTES.
Corneal and conjunctival dryness due to deficient tear production, predominantly in menopausal and post-menopausal women. Filamentary keratitis or erosion of the conjunctival and corneal epithelium may be caused by these disorders. Sensation of the presence of a foreign body in the eye and burning of the eyes may occur.
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
Chemical or physical agents that protect the skin from sunburn and erythema by absorbing or blocking ultraviolet radiation.
Conjunctivitis is an inflammation or infection of the conjunctiva, the transparent membrane that lines the inner surface of the eyelids and covers the white part of the eye, resulting in symptoms such as redness, swelling, itching, burning, discharge, and increased sensitivity to light.
Abnormally low intraocular pressure often related to chronic inflammation (uveitis).
The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)
A republic in southern Africa, east of ZAMBIA and BOTSWANA and west of MOZAMBIQUE. Its capital is Harare. It was formerly called Rhodesia and Southern Rhodesia.
A family of large adaptin protein complex subunits of approximately 90-130 kDa in size.
The transparent, semigelatinous substance that fills the cavity behind the CRYSTALLINE LENS of the EYE and in front of the RETINA. It is contained in a thin hyaloid membrane and forms about four fifths of the optic globe.
Recording of electric potentials in the retina after stimulation by light.
Voluntary or reflex-controlled movements of the eye.
Biochemical identification of mutational changes in a nucleotide sequence.
An injury to the skin causing erythema, tenderness, and sometimes blistering and resulting from excessive exposure to the sun. The reaction is produced by the ultraviolet radiation in sunlight.
Spontaneous or near spontaneous bleeding caused by a defect in clotting mechanisms (BLOOD COAGULATION DISORDERS) or another abnormality causing a structural flaw in the blood vessels (HEMOSTATIC DISORDERS).
An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterized by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its center, and provides the best phototropic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. (From Cline et al., Dictionary of Visual Science, 4th ed)
Diseases of the cornea.
The clear, watery fluid which fills the anterior and posterior chambers of the eye. It has a refractive index lower than the crystalline lens, which it surrounds, and is involved in the metabolism of the cornea and the crystalline lens. (Cline et al., Dictionary of Visual Science, 4th ed, p319)
A naturally occurring lipid pigment with histochemical characteristics similar to lipofuscin. It accumulates in various tissues in certain experimental and pathological conditions.
An amino acid-specifying codon that has been converted to a stop codon (CODON, TERMINATOR) by mutation. Its occurance is abnormal causing premature termination of protein translation and results in production of truncated and non-functional proteins. A nonsense mutation is one that converts an amino acid-specific codon to a stop codon.
Congenital absence of or defects in structures of the eye; may also be hereditary.

Albinism: its implications for refractive development. (1/72)

PURPOSE: Albinism involves the mutation of one or more of the genes associated with melanin synthesis and has many ramifications for vision. This study focuses on the refractive implications of albinism in the context of emmetropization. METHODS: Refractive, biometric, and visual acuity data were collected for a group of 25 albino individuals that included the following: 18 oculocutaneous (13 tyrosine positive, 5 tyrosine negative); 7 ocular (2 autosomal recessive, 5 sex-linked recessive). Their age range was 3 to 51 years. All exhibited horizontal pendular nystagmus. RESULTS: There were no statistically significant differences relating to albino subtype for any of the measured parameters. All the subjects had reduced visual acuity (mean: 0.90, logMAR) and overall, there was a bias toward hyperopia in their refractive errors (mean: + 1.07 D). However the refractive errors of the group covered a broad range (SD: 4.67 D) and included both high myopia and high hyperopia. An axial origin to the refractive errors is implied by the high correlation between refractive errors and axial lengths. Refractive astigmatism averaged 2.37 D and was consistently with-the-rule and highly correlated with corneal astigmatism, which was also with-the-rule. Meridional analysis of the refractive data indicated that the vertical meridian for hyperopic subjects was consistently nearer emmetropia compared to their horizontal meridian. Myopic subjects showed the opposite trend. CONCLUSIONS: The overall refractive profile of the subjects is consistent with emmetropization being impaired in albinism. However, the refractive errors of hyperopic subjects also can be explained in terms of "meridional emmetropization." The contrasting refractive profiles of myopic subjects may reflect operational constraints of the emmetropization process.  (+info)

Oa1 knock-out: new insights on the pathogenesis of ocular albinism type 1. (2/72)

Ocular albinism type I (OA1) is an X-linked disorder characterized by severe reduction of visual acuity, strabismus, photophobia and nystagmus. Ophthalmologic examination reveals hypopigmentation of the retina, foveal hypoplasia and iris translucency. Microscopic examination of both retinal pigment epithelium (RPE) and skin melanocytes shows the presence of large pigment granules called giant melanosomes or macromelanosomes. In this study, we have generated and characterized Oa1-deficient mice by gene targeting (KO). The KO males are viable, fertile and phenotypically indistinguishable from the wild-type littermates. Ophthalmologic examination shows hypopigmentation of the ocular fundus in mutant animals compared with wild-type. Analysis of the retinofugal pathway reveals a reduction in the size of the uncrossed pathway, demonstrating a misrouting of the optic fibres at the chiasm, as observed in OA1 patients. Microscopic examination of the RPE shows the presence of giant melanosomes comparable with those described in OA1 patients. Ultrastructural analysis of the RPE cells, suggests that the giant melanosomes may form by abnormal growth of single melanosomes, rather than the fusion of several, shedding light on the pathogenesis of ocular albinism.  (+info)

Expression pattern of the ocular albinism type 1 (Oa1) gene in the murine retinal pigment epithelium. (3/72)

PURPOSE: Mutations in the OA1 gene cause ocular albinism type 1 (OA1), an X-linked form of albinism affecting only the eye, with skin pigmentation appearing normal. To better understand the pathogenesis of this disease the time of onset and the pattern of expression of the mouse homolog of the OA1 gene were monitored during eye development. The localization of Oa1 mRNA was studied and compared with the expression of other genes involved in melanosomal biogenesis. METHODS: The Oa1 expression pattern during eye development and after birth was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. Localization of Oa1 mRNA was compared with TYROSINASE: (TYR:), pink-eyed dilution (p), and Pax2 expression patterns. RESULTS: RT-PCR revealed that Oa1 expression began at embryonic day (E)10.5 and was maintained until adulthood. By in situ hybridization analysis Oa1 transcripts were detected in the retinal pigment epithelium (RPE) beginning at E10.5 in the dorsal part of the eyecup and in the same area where transcripts of other genes involved in pigmentation are found. Of note, the expression pattern of these genes was complementary to Pax2 expression, which was restricted to the ventral side of the optic cup. At later stages, expression of Oa1, TYR:, and p expanded to the entire RPE and ciliary body. CONCLUSIONS: Oa1 expression can be detected at early stages of RPE development, together with other genes involved in pigmentation defects. Oa1 is likely to play an important function in melanosomal biogenesis in the RPE beginning during the earliest steps of melanosome formation.  (+info)

Defective intracellular transport and processing of OA1 is a major cause of ocular albinism type 1. (4/72)

Ocular albinism type 1 (OA1) is an X-linked disorder mainly characterized by a severe reduction of visual acuity, hypopigmentation of the retina and the presence of macromelanosomes in the skin and eyes. Various types of mutation have been identified within the OA1 gene in patients with the disorder, including several missense mutations of unknown functional significance. In order to shed light into the molecular pathogenesis of ocular albinism and possibly define critical functional domains within the OA1 protein, we characterized 19 independent missense mutations with respect to processing and subcellular distribution on expression in COS-7 cells. Our analysis indicates the presence of at least two distinct biochemical defects associated with the different missense mutations. Eleven of the nineteen OA1 mutants (approximately 60%) were retained in the endoplasmic reticulum, showing defecNStive intracellular transport and glycosylation, consistent with protein misfolding. The remaining eight of the nineteen OA1 mutants (approximately 40%) displayed sorting and processing behaviours indistinguishable from those of the wild-type protein. Consistent with our recent findings that OA1 represents a novel type of intracellular G protein-coupled receptor (GPCR), we found that most of these latter mutations cluster within the second and third cytosolic loops, two regions that in canonical GPCRs are known to be critical for their downstream signaling, including G protein-coupling and effector activation. The biochemical analysis of OA1 mutations performed in this study provides important insights into the structure-function relationships of the OA1 protein and implies protein misfolding as a major pathogenic mechanism in OA1.  (+info)

Behavioral visual responses of wild-type and hypopigmented zebrafish. (5/72)

Zebrafish possess three classes of chromatophores that include iridophores, melanophores, and xanthophores. Mutations that lack one or two classes of chromatophores have been isolated or genetically constructed. Using a behavioral assay based on visually mediated escape responses, we measured the visual response of fully and partially pigmented zebrafish. In zebrafish that lack iridophores (roy mutants), the behavioral visual responses were similar to those of wild-type animals except at low contrast stimulation. In the absence of melanophores (albino mutants) or both melanophores and iridophores (ruby mutants), the behavioral visual responses were normal under moderate illumination but reduced when tested under dim or bright conditions or under low contrast stimulation. Together, the data suggest that screening pigments in the retina play a role in the regulation of behavioral visual responses and are necessary for avoiding "scatter" under bright light conditions.  (+info)

Correlation between rod photoreceptor numbers and levels of ocular pigmentation. (6/72)

PURPOSE: Ocular melanin synthesis modulates rod photoreceptor production, because in albino eyes, rod numbers are reduced by approximately 30%. In this study, rod numbers and ocular rhodopsin concentrations were measured in intermediate pigmentation phenotypes to determine whether proportional reductions in melanin are correlated with proportional changes in rod numbers. Further, patterns of cell production and death were examined around the time of birth, when rod production peaks, to determine whether there are abnormalities in these features associated with hypopigmentation. METHODS: Four mouse pigmentation phenotypes were used: fully pigmented, albino, Beige, and Himalayan. The latter two are intermediate-pigmentation phenotypes, with Beige having markedly more pigment than Himalayan. Ocular melanin concentrations were measured during development and at maturity. Rods were counted at maturity and measurements of ocular rhodopsin undertaken. Mitotic and pyknotic cells were also counted in neonates. RESULTS: Rods and ocular rhodopsin were reduced in both Beige and Himalayan mice below levels found in fully pigmented mice, but not to levels found in albino animals. This was more marked in Himalayan than Beige mice, reflecting the lower concentration of melanin found in the former compared with the latter, both in development and at maturity. Although patterns of cell production were elevated in the hypopigmented animals, such patterns varied. CONCLUSIONS: Rod numbers are modulated within a range between that in fully pigmented and albino phenotypes by the concentration of ocular melanin. However, in these animals, there is no obvious correlation between these events and patterns of cell production and death in neonates.  (+info)

Motor and sensory characteristics of infantile nystagmus. (7/72)

BACKGROUND/AIMS: Past studies have explored some of the associations between particular motor and sensory characteristics and specific categories of non-neurological infantile nystagmus. The purpose of this case study is to extend this body of work significantly by describing the trends and associations found in a database of 224 subjects who have undergone extensive clinical and psychophysical evaluations. METHODS: The records of 224 subjects with infantile nystagmus were examined, where 62% were idiopaths, 28% albinos, and 10% exhibited ocular anomalies. Recorded variables included age, mode of inheritance, birth history, nystagmus presentation, direction of the nystagmus, waveform types, spatial and temporal null zones, head postures and nodding, convergence, foveation, ocular alignment, refractive error, visual acuity, stereoacuity, and oscillopsia. RESULTS: The age distribution of the 224 patients was between 1 month and 71 years, with the mean age and mode being 23 (SD 16) years and 16-20 years respectively. By far the most common pattern of inheritance was found to be autosomal dominant (n = 40), with the nystagmus being observed by the age of 6 months in 87% of the sample (n = 128). 139 (62%) of the 224 subjects were classified as idiopaths, 63 (28%) as albinos, and 22 (10%) exhibited ocular anomalies. Conjugate uniplanar horizontal oscillations were found in 174 (77.7%) of the sample. 32 (14.3%) had a torsional component to their nystagmus. 182 (81.2%) were classed as congenital nystagmus (CN), 32 (14.3%) as manifest latent nystagmus (MLN), and 10 (4.5%) as a CN/MLN hybrid. Neither CN nor MLN waveforms were related to any of the three subject groups (idiopaths, albinos, and ocular anomalies) MLN was found in idiopaths and albinos, but most frequently in the ocular anomaly group. The most common oscillation was a horizontal jerk with extended foveation (n = 49; 27%). The amplitudes and frequencies of the nystagmus ranged between 0.3-15.7 degrees and 0.5-8 Hz, respectively. Periodic alternating nystagmus is commonly found in albinos. Albino subjects did not show a statistically significantly higher nystagmus intensity when compared with the idiopaths (p>0.01). 105 of 143 subjects (73%) had spatial nulls within plus or minus 10 degrees of the primary position although 98 subjects (69%) employed a compensatory head posture. Subjects with spatial null zones at or beyond plus or minus 20 degrees always adopted constant head postures. Head nodding was found in 38 subjects (27% of the sample). Horizontal tropias were very common (133 out of 213; 62.4%) and all but one of the 32 subjects with MLN exhibited a squint. Adult visual acuity is strongly related to the duration and accuracy of the foveation period. Visual acuity and stereoacuity were significantly better (p<0.01) in the idiopaths compared to the albino and ocular anomaly groups. 66 subjects out of a sample of 168 (39%) indicated that they had experienced oscillopsia at some time. CONCLUSIONS: There are strong ocular motor and sensory patterns and associations that can help define an infantile nystagmus. These include the nystagmus being bilateral, conjugate, horizontal uniplanar, and having an accelerating slow phase (that is, CN). Decelerating slow phases (that is, MLN) are frequently associated with strabismus and early form deprivation. Waveform shape (CN or MLN) is not pathognomonic of any of the three subject groups (idiopaths, albinos, or ocular anomalies). There is no one single stand alone ocular motor characteristic that can differentiate a benign form of infantile nystagmus (CN, MLN) from a neurological one. Rather, the clinician must consider a host of clinical features.  (+info)

Identification of three novel OA1 gene mutations identified in three families misdiagnosed with congenital nystagmus and carrier status determination by real-time quantitative PCR assay. (8/72)

BACKGROUND: X-linked ocular albinism type 1 (OA1) is caused by mutations in OA1 gene, which encodes a membrane glycoprotein localised to melanosomes. OA1 mainly affects pigment production in the eye, resulting in optic changes associated with albinism including hypopigmentation of the retina, nystagmus, strabismus, foveal hypoplasia, abnormal crossing of the optic fibers and reduced visual acuity. Affected Caucasian males usually appear to have normal skin and hair pigment. RESULTS: We identified three previously undescribed mutations consisting of two intragenic deletions (one encompassing exon 6, the other encompassing exons 7-8), and a point mutation (310delG) in exon 2. We report the development of a new method for diagnosis of heterozygous deletions in OA1 gene based on measurement of gene copy number using real-time quantitative PCR from genomic DNA. CONCLUSION: The identification of OA1 mutations in families earlier reported as families with hereditary nystagmus indicate that ocular albinism type 1 is probably underdiagnosed. Our method of real-time quantitative PCR of OA1 exons with DMD exon as external standard performed on the LightCycler trade mark allows quick and accurate carrier-status assessment for at-risk females.  (+info)

Albinism is a group of genetic disorders that result in little or no production of melanin, the pigment responsible for coloring skin, hair, and eyes. It is caused by mutations in genes involved in the production of melanin. There are several types of albinism, including oculocutaneous albinism (OCA) and ocular albinism (OA). OCA affects the skin, hair, and eyes, while OA primarily affects the eyes.

People with albinism typically have very pale skin, white or light-colored hair, and light-colored eyes. They may also have vision problems, such as sensitivity to light (photophobia), rapid eye movements (nystagmus), and decreased visual acuity. The severity of these symptoms can vary depending on the type and extent of albinism.

Albinism is inherited in an autosomal recessive manner, which means that an individual must inherit two copies of the mutated gene, one from each parent, in order to have the condition. If both parents are carriers of a mutated gene for albinism, they have a 25% chance with each pregnancy of having a child with albinism.

There is no cure for albinism, but individuals with the condition can take steps to protect their skin and eyes from the sun and use visual aids to help with vision problems. It is important for people with albinism to undergo regular eye examinations and to use sun protection, such as sunscreen, hats, and sunglasses, to prevent skin damage and skin cancer.

Oculocutaneous albinism (OCA) is a group of genetic disorders characterized by reduced or complete absence of melanin pigment in the eyes, skin, and hair. Melanin is the pigment responsible for giving color to our skin, hair, and eyes. OCA affects both the eyes (oculo-) and the skin (cutaneous), hence the name oculocutaneous albinism.

There are several types of OCA, each caused by different genetic mutations affecting melanin production. The most common forms include:

1. OCA1: This type is further divided into two subtypes - OCA1A and OCA1B. OCA1A is characterized by complete absence of melanin in the eyes, skin, and hair from birth. Individuals with this condition have white hair, very light skin, and pale blue or gray irises. OCA1B, on the other hand, presents with reduced melanin production, leading to lighter-than-average skin, hair, and eye color at birth. Over time, some melanin may be produced, resulting in milder pigmentation changes compared to OCA1A.
2. OCA2: This form of albinism is caused by mutations in the tyrosinase-related protein 1 (TYRP1) gene, which plays a role in melanin production. Individuals with OCA2 typically have light brown or yellowish skin, golden or straw-colored hair, and lighter irises compared to their family members without albinism.
3. OCA3: Also known as Rufous oculocutaneous albinism (ROCA), this type is caused by mutations in the tyrosinase gene (TYR). It primarily affects people of African descent, leading to reddish-brown hair, light brown skin, and normal or near-normal eye color.
4. OCA4: This form of albinism results from mutations in the membrane-associated transporter protein (MATP) gene, which is involved in melanin transport within cells. Individuals with OCA4 usually have light brown skin, yellowish or blond hair, and lighter irises compared to their family members without albinism.

Regardless of the type, all individuals with oculocutaneous albinism face similar challenges, including reduced vision due to abnormal eye development (nystagmus, strabismus, and farsightedness) and increased sensitivity to sunlight (photophobia). Proper management, such as wearing UV-protective sunglasses, hats, and sunscreen, can help protect their skin and eyes from damage.

Tyrosinase, also known as monophenol monooxygenase, is an enzyme (EC that catalyzes the ortho-hydroxylation of monophenols (like tyrosine) to o-diphenols (like L-DOPA) and the oxidation of o-diphenols to o-quinones. This enzyme plays a crucial role in melanin synthesis, which is responsible for the color of skin, hair, and eyes in humans and animals. Tyrosinase is found in various organisms, including plants, fungi, and animals. In humans, tyrosinase is primarily located in melanocytes, the cells that produce melanin. The enzyme's activity is regulated by several factors, such as pH, temperature, and metal ions like copper, which are essential for its catalytic function.

Hermanski-Pudlak Syndrome (HPS) is a rare genetic disorder characterized by the triad of albinism, bleeding disorders, and lysosomal storage disease. It is caused by mutations in any one of several genes involved in biogenesis of lysosome-related organelles (LROs), such as melanosomes in melanocytes, platelet dense granules, and lung lamellar bodies.

The albinism in HPS results from abnormal melanosome biogenesis, leading to decreased pigmentation in the skin, hair, and eyes. The bleeding disorder is due to defective platelet dense granules, which are necessary for normal clotting function. This can result in prolonged bleeding times and easy bruising.

The lysosomal storage disease component of HPS is characterized by the accumulation of ceroid lipofuscin within LROs, leading to progressive damage to affected tissues. The most common form of HPS (HPS-1) also involves pulmonary fibrosis, which can lead to respiratory failure and death in the third or fourth decade of life.

There are currently seven known subtypes of HPS, each caused by mutations in different genes involved in LRO biogenesis. The clinical features and severity of HPS can vary widely between subtypes and even within families with the same genetic mutation.

Pathological nystagmus is an abnormal, involuntary movement of the eyes that can occur in various directions (horizontal, vertical, or rotatory) and can be rhythmical or arrhythmic. It is typically a result of a disturbance in the vestibular system, central nervous system, or ocular motor pathways. Pathological nystagmus can cause visual symptoms such as blurred vision, difficulty with fixation, and oscillopsia (the sensation that one's surroundings are moving). The type, direction, and intensity of the nystagmus may vary depending on the underlying cause, which can include conditions such as brainstem or cerebellar lesions, multiple sclerosis, drug toxicity, inner ear disorders, and congenital abnormalities.

Hypopigmentation is a medical term that refers to a condition where there is a decrease in the amount of pigment (melanin) in the skin, resulting in lighter patches or spots on the skin. This can occur due to various reasons such as skin injuries, certain skin disorders like vitiligo, fungal infections, burns, or as a side effect of some medical treatments like chemotherapy or radiation therapy. It is different from albinism, which is a genetic condition where the body is unable to produce melanin at all.

I'm afraid there seems to be a misunderstanding. Folklore is not a medical term and does not have a medical definition. It refers to the traditional customs, tales, sayings, dances, or art forms that are passed down from generation to generation within a culture or community. If you have any questions related to medical terminology or health-related topics, I'd be happy to help!

Melanosomes are membrane-bound organelles found in melanocytes, the pigment-producing cells in the skin, hair, and eyes. They contain the pigment melanin, which is responsible for giving color to these tissues. Melanosomes are produced in the melanocyte and then transferred to surrounding keratinocytes in the epidermis via a process called cytocrinesis. There are four stages of melanosome development: stage I (immature), stage II (developing), stage III (mature), and stage IV (degrading). The amount and type of melanin in the melanosomes determine the color of an individual's skin, hair, and eyes. Mutations in genes involved in melanosome biogenesis or function can lead to various pigmentation disorders, such as albinism.

Congenital nystagmus is a type of involuntary eye movement that is present at birth or develops within the first few months of life. It is characterized by rhythmic oscillations or repetitive, rapid movements of the eyes in either horizontal, vertical, or rotatory directions. These movements can impair vision and may be associated with other ocular conditions such as albinism, congenital cataracts, or optic nerve hypoplasia. The exact cause of congenital nystagmus is not fully understood, but it is believed to result from abnormal development or dysfunction in the areas of the brain that control eye movements. In some cases, congenital nystagmus may be inherited as a genetic trait. Treatment options for congenital nystagmus include corrective lenses, prism glasses, surgery, and vision therapy, depending on the underlying cause and severity of the condition.

The eye is the organ of sight, primarily responsible for detecting and focusing on visual stimuli. It is a complex structure composed of various parts that work together to enable vision. Here are some of the main components of the eye:

1. Cornea: The clear front part of the eye that refracts light entering the eye and protects the eye from harmful particles and microorganisms.
2. Iris: The colored part of the eye that controls the amount of light reaching the retina by adjusting the size of the pupil.
3. Pupil: The opening in the center of the iris that allows light to enter the eye.
4. Lens: A biconvex structure located behind the iris that further refracts light and focuses it onto the retina.
5. Retina: A layer of light-sensitive cells (rods and cones) at the back of the eye that convert light into electrical signals, which are then transmitted to the brain via the optic nerve.
6. Optic Nerve: The nerve that carries visual information from the retina to the brain.
7. Vitreous: A clear, gel-like substance that fills the space between the lens and the retina, providing structural support to the eye.
8. Conjunctiva: A thin, transparent membrane that covers the front of the eye and the inner surface of the eyelids.
9. Extraocular Muscles: Six muscles that control the movement of the eye, allowing for proper alignment and focus.

The eye is a remarkable organ that allows us to perceive and interact with our surroundings. Various medical specialties, such as ophthalmology and optometry, are dedicated to the diagnosis, treatment, and management of various eye conditions and diseases.

Ocular hypertension is a medical condition characterized by elevated pressure within the eye (intraocular pressure or IOP), which is higher than normal but not necessarily high enough to cause any visible damage to the optic nerve or visual field loss. It serves as a significant risk factor for developing glaucoma, a sight-threatening disease.

The normal range of intraocular pressure is typically between 10-21 mmHg (millimeters of mercury). Ocular hypertension is often defined as an IOP consistently above 21 mmHg, although some studies suggest that even pressures between 22-30 mmHg may not cause damage in all individuals. Regular monitoring and follow-up with an ophthalmologist are essential for people diagnosed with ocular hypertension to ensure early detection and management of any potential glaucomatous changes. Treatment options include medications, laser therapy, or surgery to lower the IOP and reduce the risk of glaucoma onset.

Eye color is a characteristic determined by variations in a person's genes. The color of the eyes depends on the amount and type of pigment called melanin found in the eye's iris.

There are three main types of eye colors: brown, blue, and green. Brown eyes have the most melanin, while blue eyes have the least. Green eyes have a moderate amount of melanin combined with a golden tint that reflects light to give them their unique color.

Eye color is a polygenic trait, which means it is influenced by multiple genes. The two main genes responsible for eye color are OCA2 and HERC2, both located on chromosome 15. These genes control the production, transport, and storage of melanin in the iris.

It's important to note that eye color can change during infancy and early childhood due to the development of melanin in the iris. Additionally, some medications or medical conditions may also cause changes in eye color over time.

Melanocytes are specialized cells that produce, store, and transport melanin, the pigment responsible for coloring of the skin, hair, and eyes. They are located in the bottom layer of the epidermis (the outermost layer of the skin) and can also be found in the inner ear and the eye's retina. Melanocytes contain organelles called melanosomes, which produce and store melanin.

Melanin comes in two types: eumelanin (black or brown) and pheomelanin (red or yellow). The amount and type of melanin produced by melanocytes determine the color of a person's skin, hair, and eyes. Exposure to UV radiation from sunlight increases melanin production as a protective response, leading to skin tanning.

Melanocyte dysfunction or abnormalities can lead to various medical conditions, such as albinism (lack of melanin production), melasma (excessive pigmentation), and melanoma (cancerous growth of melanocytes).

Pigmentation, in a medical context, refers to the coloring of the skin, hair, or eyes due to the presence of pigment-producing cells called melanocytes. These cells produce a pigment called melanin, which determines the color of our skin, hair, and eyes.

There are two main types of melanin: eumelanin and pheomelanin. Eumelanin is responsible for brown or black coloration, while pheomelanin produces a red or yellow hue. The amount and type of melanin produced by melanocytes can vary from person to person, leading to differences in skin color and hair color.

Changes in pigmentation can occur due to various factors such as genetics, exposure to sunlight, hormonal changes, inflammation, or certain medical conditions. For example, hyperpigmentation refers to an excess production of melanin that results in darkened patches on the skin, while hypopigmentation is a condition where there is a decreased production of melanin leading to lighter or white patches on the skin.

Ocular albinism is a type of albinism that primarily affects the eyes. It is a genetic disorder characterized by the reduction or absence of melanin, the pigment responsible for coloring the skin, hair, and eyes. In ocular albinism, melanin production is deficient in the eyes, leading to various eye abnormalities.

The main features of ocular albinism include:

1. Nystagmus: Rapid, involuntary back-and-forth movement of the eyes.
2. Iris transillumination: The iris appears translucent due to the lack of pigment, allowing light to pass through easily. This can be observed using a light source shone into the eye.
3. Foveal hypoplasia: Underdevelopment or absence of the fovea, a small pit in the retina responsible for sharp, central vision.
4. Photophobia: Increased sensitivity to light due to the lack of pigment in the eyes.
5. Strabismus: Misalignment of the eyes, which can result in double vision or lazy eye.
6. Reduced visual acuity: Decreased ability to see clearly, even with corrective lenses.

Ocular albinism is typically inherited as an X-linked recessive trait, meaning it primarily affects males, while females can be carriers of the condition. However, there are also autosomal recessive forms of ocular albinism that can affect both males and females equally. Treatment for ocular albinism usually involves managing symptoms with corrective lenses, low-vision aids, and vision therapy to improve visual skills.

Melanin is a pigment that determines the color of skin, hair, and eyes in humans and animals. It is produced by melanocytes, which are specialized cells found in the epidermis (the outer layer of the skin) and the choroid (the vascular coat of the eye). There are two main types of melanin: eumelanin and pheomelanin. Eumelanin is a black or brown pigment, while pheomelanin is a red or yellow pigment. The amount and type of melanin produced by an individual can affect their skin and hair color, as well as their susceptibility to certain diseases, such as skin cancer.

Piebaldism is a rare genetic disorder characterized by the presence of white patches of skin and hair due to a lack of melanin, the pigment that gives color to skin, hair, and eyes. These patches are present from birth and typically involve the forehead, chin, and midline of the body. The condition is caused by mutations in the KIT or SLC45A2 genes and is usually inherited in an autosomal dominant pattern, meaning only one copy of the altered gene is needed to cause the disorder. Piebaldism is not harmful to a person's overall health, but it can have significant psychological effects due to its impact on appearance.

Ocular toxoplasmosis is an inflammatory eye disease caused by the parasitic infection of Toxoplasma gondii in the eye's retina. It can lead to lesions and scarring in the retina, resulting in vision loss or impairment. The severity of ocular toxoplasmosis depends on the location and extent of the infection in the eye. In some cases, it may cause only mild symptoms, while in others, it can result in severe damage to the eye. Ocular toxoplasmosis is usually treated with medications that target the Toxoplasma gondii parasite, such as pyrimethamine and sulfadiazine, often combined with corticosteroids to reduce inflammation.

Pigmentation disorders are conditions that affect the production or distribution of melanin, the pigment responsible for the color of skin, hair, and eyes. These disorders can cause changes in the color of the skin, resulting in areas that are darker (hyperpigmentation) or lighter (hypopigmentation) than normal. Examples of pigmentation disorders include melasma, age spots, albinism, and vitiligo. The causes, symptoms, and treatments for these conditions can vary widely, so it is important to consult a healthcare provider for an accurate diagnosis and treatment plan.

Evoked potentials, visual, also known as visually evoked potentials (VEPs), are electrical responses recorded from the brain following the presentation of a visual stimulus. These responses are typically measured using electroencephalography (EEG) and can provide information about the functioning of the visual pathways in the brain.

There are several types of VEPs, including pattern-reversal VEPs and flash VEPs. Pattern-reversal VEPs are elicited by presenting alternating checkerboard patterns, while flash VEPs are elicited by flashing a light. The responses are typically analyzed in terms of their latency (the time it takes for the response to occur) and amplitude (the size of the response).

VEPs are often used in clinical settings to help diagnose and monitor conditions that affect the visual system, such as multiple sclerosis, optic neuritis, and brainstem tumors. They can also be used in research to study the neural mechanisms underlying visual perception.

Eye proteins, also known as ocular proteins, are specific proteins that are found within the eye and play crucial roles in maintaining proper eye function and health. These proteins can be found in various parts of the eye, including the cornea, iris, lens, retina, and other structures. They perform a wide range of functions, such as:

1. Structural support: Proteins like collagen and elastin provide strength and flexibility to the eye's tissues, enabling them to maintain their shape and withstand mechanical stress.
2. Light absorption and transmission: Proteins like opsins and crystallins are involved in capturing and transmitting light signals within the eye, which is essential for vision.
3. Protection against damage: Some eye proteins, such as antioxidant enzymes and heat shock proteins, help protect the eye from oxidative stress, UV radiation, and other environmental factors that can cause damage.
4. Regulation of eye growth and development: Various growth factors and signaling molecules, which are protein-based, contribute to the proper growth, differentiation, and maintenance of eye tissues during embryonic development and throughout adulthood.
5. Immune defense: Proteins involved in the immune response, such as complement components and immunoglobulins, help protect the eye from infection and inflammation.
6. Maintenance of transparency: Crystallin proteins in the lens maintain its transparency, allowing light to pass through unobstructed for clear vision.
7. Neuroprotection: Certain eye proteins, like brain-derived neurotrophic factor (BDNF), support the survival and function of neurons within the retina, helping to preserve vision.

Dysfunction or damage to these eye proteins can contribute to various eye disorders and diseases, such as cataracts, age-related macular degeneration, glaucoma, diabetic retinopathy, and others.

Photophobia is a condition characterized by an abnormal sensitivity to light. It's not a fear of light, despite the name suggesting otherwise. Instead, it refers to the discomfort or pain felt in the eyes due to exposure to light, often leading to a strong desire to avoid light. This can include both natural and artificial light sources.

The severity of photophobia can vary greatly among individuals. Some people may only experience mild discomfort in bright light conditions, while others may find even moderate levels of light intolerable. It can be a symptom of various underlying health issues, including eye diseases or disorders like uveitis, keratitis, corneal abrasions, or optic neuritis, as well as systemic conditions such as migraines, meningitis, or certain medications that increase light sensitivity.

Skin pigmentation is the coloration of the skin that is primarily determined by two types of melanin pigments, eumelanin and pheomelanin. These pigments are produced by melanocytes, which are specialized cells located in the epidermis. Eumelanin is responsible for brown or black coloration, while pheomelanin produces a red or yellow hue.

The amount and distribution of melanin in the skin can vary depending on genetic factors, age, sun exposure, and various other influences. Increased production of melanin in response to UV radiation from the sun helps protect the skin from damage, leading to darkening or tanning of the skin. However, excessive sun exposure can also cause irregular pigmentation, such as sunspots or freckles.

Abnormalities in skin pigmentation can result from various medical conditions, including albinism (lack of melanin production), vitiligo (loss of melanocytes leading to white patches), and melasma (excessive pigmentation often caused by hormonal changes). These conditions may require medical treatment to manage or improve the pigmentation issues.

Chediak-Higashi Syndrome is a rare autosomal recessive disorder characterized by partial albinism, photophobia, bleeding diathesis, recurrent infections, and progressive neurological degeneration. It is caused by mutations in the LYST gene, which leads to abnormalities in lysosomes, melanosomes, and neutrophil granules. The disorder is named after two Mexican hematologists, Dr. Chediak and Dr. Higashi, who first described it in 1952.

The symptoms of Chediak-Higashi Syndrome typically appear in early childhood and include light skin and hair, blue or gray eyes, and a sensitivity to light. Affected individuals may also have bleeding problems due to abnormal platelets, and they are prone to recurrent bacterial infections, particularly of the skin, gums, and respiratory system.

The neurological symptoms of Chediak-Higashi Syndrome can include poor coordination, difficulty walking, and seizures. The disorder can also affect the immune system, leading to an accelerated phase known as the "hemophagocytic syndrome," which is characterized by fever, enlarged liver and spleen, and abnormal blood counts.

There is no cure for Chediak-Higashi Syndrome, and treatment typically focuses on managing the symptoms of the disorder. This may include antibiotics to treat infections, medications to control bleeding, and physical therapy to help with mobility issues. In some cases, bone marrow transplantation may be recommended as a potential cure for the disorder.

Membrane transport proteins are specialized biological molecules, specifically integral membrane proteins, that facilitate the movement of various substances across the lipid bilayer of cell membranes. They are responsible for the selective and regulated transport of ions, sugars, amino acids, nucleotides, and other molecules into and out of cells, as well as within different cellular compartments. These proteins can be categorized into two main types: channels and carriers (or pumps). Channels provide a passive transport mechanism, allowing ions or small molecules to move down their electrochemical gradient, while carriers actively transport substances against their concentration gradient, requiring energy usually in the form of ATP. Membrane transport proteins play a crucial role in maintaining cell homeostasis, signaling processes, and many other physiological functions.

Electronystagmography (ENG) is a medical test used to assess the function of the vestibular system, which is responsible for maintaining balance and eye movements. This test measures involuntary eye movements, called nystagmus, which can be indicative of various conditions affecting the inner ear or brainstem.

During the ENG test, electrodes are placed around the eyes to record eye movements while the patient undergoes a series of stimuli, such as changes in head position, visual stimuli, and caloric irrigations (where warm or cool water is introduced into the ear canal to stimulate the inner ear). The recorded data is then analyzed to evaluate the function of the vestibular system and identify any abnormalities.

ENG testing can help diagnose conditions such as vestibular neuritis, labyrinthitis, benign paroxysmal positional vertigo (BPPV), Meniere's disease, and other balance disorders. It is also used to assess the effectiveness of various treatments for these conditions.

Visual acuity is a measure of the sharpness or clarity of vision. It is usually tested by reading an eye chart from a specific distance, such as 20 feet (6 meters). The standard eye chart used for this purpose is called the Snellen chart, which contains rows of letters that decrease in size as you read down the chart.

Visual acuity is typically expressed as a fraction, with the numerator representing the testing distance and the denominator indicating the smallest line of type that can be read clearly. For example, if a person can read the line on the eye chart that corresponds to a visual acuity of 20/20, it means they have normal vision at 20 feet. If their visual acuity is 20/40, it means they must be as close as 20 feet to see what someone with normal vision can see at 40 feet.

It's important to note that visual acuity is just one aspect of overall vision and does not necessarily reflect other important factors such as peripheral vision, depth perception, color vision, or contrast sensitivity.

Ocular dominance refers to the preference of one eye over the other in terms of visual perception and processing. In other words, it is the tendency for an individual to rely more heavily on the input from one particular eye when interpreting visual information. This can have implications in various visual tasks such as depth perception, aiming, and targeting.

Ocular dominance can be determined through a variety of tests, including the Miles test, the Porta test, or simply by observing which eye a person uses to align a visual target. It is important to note that ocular dominance does not necessarily indicate any sort of visual impairment or deficit; rather, it is a normal variation in the way that visual information is processed by the brain.

X-linked genetic diseases refer to a group of disorders caused by mutations in genes located on the X chromosome. These conditions primarily affect males since they have only one X chromosome and therefore don't have a second normal copy of the gene to compensate for the mutated one. Females, who have two X chromosomes, are typically less affected because they usually have one normal copy of the gene on their other X chromosome.

Examples of X-linked genetic diseases include Duchenne and Becker muscular dystrophy, hemophilia A and B, color blindness, and fragile X syndrome. Symptoms and severity can vary widely depending on the specific condition and the nature of the genetic mutation involved. Treatment options depend on the particular disease but may include physical therapy, medication, or in some cases, gene therapy.

Ocular tonometry is a medical test used to measure the pressure inside the eye, also known as intraocular pressure (IOP). This test is an essential part of diagnosing and monitoring glaucoma, a group of eye conditions that can cause vision loss and blindness due to damage to the optic nerve from high IOP.

The most common method of ocular tonometry involves using a tonometer device that gently touches the front surface of the eye (cornea) with a small probe or prism. The device measures the amount of force required to flatten the cornea slightly, which correlates with the pressure inside the eye. Other methods of ocular tonometry include applanation tonometry, which uses a small amount of fluorescein dye and a blue light to measure the IOP, and rebound tonometry, which uses a lightweight probe that briefly touches the cornea and then bounces back to determine the IOP.

Regular ocular tonometry is important for detecting glaucoma early and preventing vision loss. It is typically performed during routine eye exams and may be recommended more frequently for individuals at higher risk of developing glaucoma, such as those with a family history of the condition or certain medical conditions like diabetes.

I apologize for any confusion, but "Pontederiaceae" is not a medical term. It is a taxonomic category in botany, specifically the name of a family of flowering plants that includes water hyacinth and pickerelweed. If you have any questions about a medical term or concept, I would be happy to help with those instead!

Ocular refraction is a medical term that refers to the bending of light as it passes through the optical media of the eye, including the cornea and lens. This process allows the eye to focus light onto the retina, creating a clear image. The refractive power of the eye is determined by the curvature and transparency of these structures.

In a normal eye, light rays are bent or refracted in such a way that they converge at a single point on the retina, producing a sharp and focused image. However, if the curvature of the cornea or lens is too steep or too flat, the light rays may not converge properly, resulting in a refractive error such as myopia (nearsightedness), hyperopia (farsightedness), or astigmatism.

Ocular refraction can be measured using a variety of techniques, including retinoscopy, automated refraction, and subjective refraction. These measurements are used to determine the appropriate prescription for corrective lenses such as eyeglasses or contact lenses. In some cases, ocular refractive errors may be corrected surgically through procedures such as LASIK or PRK.

I must clarify that the term "pedigree" is not typically used in medical definitions. Instead, it is often employed in genetics and breeding, where it refers to the recorded ancestry of an individual or a family, tracing the inheritance of specific traits or diseases. In human genetics, a pedigree can help illustrate the pattern of genetic inheritance in families over multiple generations. However, it is not a medical term with a specific clinical definition.

"Fundus Oculi" is a medical term that refers to the back part of the interior of the eye, including the optic disc, macula, fovea, retinal vasculature, and peripheral retina. It is the area where light is focused and then transmitted to the brain via the optic nerve, forming visual images. Examinations of the fundus oculi are crucial for detecting various eye conditions such as diabetic retinopathy, macular degeneration, glaucoma, and other retinal diseases. The examination is typically performed using an ophthalmoscope or a specialized camera called a retinal camera.

In medical terms, the iris refers to the colored portion of the eye that surrounds the pupil. It is a circular structure composed of thin, contractile muscle fibers (radial and circumferential) arranged in a regular pattern. These muscles are controlled by the autonomic nervous system and can adjust the size of the pupil in response to changes in light intensity or emotional arousal. By constricting or dilating the iris, the amount of light entering the eye can be regulated, which helps maintain optimal visual acuity under various lighting conditions.

The color of the iris is determined by the concentration and distribution of melanin pigments within the iris stroma. The iris also contains blood vessels, nerves, and connective tissue that support its structure and function. Anatomically, the iris is continuous with the ciliary body and the choroid, forming part of the uveal tract in the eye.

Eye neoplasms, also known as ocular tumors or eye cancer, refer to abnormal growths of tissue in the eye. These growths can be benign (non-cancerous) or malignant (cancerous). Eye neoplasms can develop in various parts of the eye, including the eyelid, conjunctiva, cornea, iris, ciliary body, choroid, retina, and optic nerve.

Benign eye neoplasms are typically slow-growing and do not spread to other parts of the body. They may cause symptoms such as vision changes, eye pain, or a noticeable mass in the eye. Treatment options for benign eye neoplasms include monitoring, surgical removal, or radiation therapy.

Malignant eye neoplasms, on the other hand, can grow and spread rapidly to other parts of the body. They may cause symptoms such as vision changes, eye pain, floaters, or flashes of light. Treatment options for malignant eye neoplasms depend on the type and stage of cancer but may include surgery, radiation therapy, chemotherapy, or a combination of these treatments.

It is important to note that early detection and treatment of eye neoplasms can improve outcomes and prevent complications. Regular eye exams with an ophthalmologist are recommended for early detection and prevention of eye diseases, including eye neoplasms.

Characidae is a family of freshwater fish that are commonly known as characins. They belong to the order Characiformes and can be found primarily in tropical waters of Central and South America, with a few species in Africa. The family includes over 100 genera and more than 900 described species, making it one of the most diverse families of ray-finned fishes.

Characids exhibit a wide range of body shapes, sizes, and colors, with many having adaptations for specific ecological niches. Some well-known examples of characids include piranhas (Serrasalmus spp.), tetras (Hyphessobrycon spp., Hemigrammus spp., etc.), and hatchetfish (Gasteropelecidae).

The medical significance of characids is relatively limited, as they are not typically associated with human diseases or health issues. However, some species may be kept in aquariums as pets, and proper care should be taken to maintain water quality and prevent the spread of disease among fish populations. Additionally, research on characid fishes can contribute to our understanding of evolution, ecology, and biogeography, which have broader implications for science and conservation.

"Social alienation" is not a term that has a specific medical definition in the same way that a term like "hypertension" or "diabetes" does. However, it is often used in a psychological or sociological context to describe a state of feeling disconnected or isolated from society, including feelings of loneliness, estrangement, and rejection.

In some cases, social alienation may be associated with mental health conditions such as depression, anxiety, or schizophrenia. For example, a person with social anxiety disorder may experience social alienation due to their fear of social interactions and avoidance of social situations. Similarly, a person with schizophrenia may experience social alienation due to the stigma associated with their condition and difficulties with communication and social cues.

However, it's important to note that social alienation can also occur in people without any underlying mental health conditions. Factors such as discrimination, poverty, migration, and social upheaval can all contribute to feelings of social alienation.

A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.

Catechol oxidase, also known as polyphenol oxidase, is an enzyme that catalyzes the oxidation of catechols and other phenolic compounds to quinones. These quinones can then undergo further reactions to form various pigmented compounds, such as melanins. Catechol oxidase is widely distributed in nature and is found in plants, fungi, and some bacteria. In humans, catechol oxidase is involved in the metabolism of neurotransmitters such as dopamine and epinephrine.

Ocular motility disorders refer to a group of conditions that affect the movement of the eyes. These disorders can result from nerve damage, muscle dysfunction, or brain injuries. They can cause abnormal eye alignment, limited range of motion, and difficulty coordinating eye movements. Common symptoms include double vision, blurry vision, strabismus (crossed eyes), nystagmus (involuntary eye movement), and difficulty tracking moving objects. Ocular motility disorders can be congenital or acquired and may require medical intervention to correct or manage the condition.

The pigment epithelium of the eye, also known as the retinal pigment epithelium (RPE), is a layer of cells located between the photoreceptor cells of the retina and the choroid, which is the vascular layer of the eye. The RPE plays a crucial role in maintaining the health and function of the photoreceptors by providing them with nutrients, removing waste products, and helping to regulate the light that enters the eye.

The RPE cells contain pigment granules that absorb excess light, preventing it from scattering within the eye and improving visual acuity. They also help to create a barrier between the retina and the choroid, which is important for maintaining the proper functioning of the photoreceptors. Additionally, the RPE plays a role in the regeneration of visual pigments in the photoreceptor cells, allowing us to see in different light conditions.

Damage to the RPE can lead to various eye diseases and conditions, including age-related macular degeneration (AMD), which is a leading cause of vision loss in older adults.

I believe there may be some confusion in your question as "caves" are not a medical term. A cave is a natural underground space that is large enough for a person to enter and can form in a variety of ways, such as the dissolution of limestone by acidic groundwater or the collapse of a volcanic tube. If you have any questions about geology or speleology (the study of caves), I would be happy to try to help answer those!

Chondrodysplasia punctata is a group of genetic disorders that affect the development of bones and cartilage. The condition is characterized by stippled calcifications, or spots of calcium deposits, in the cartilage that can be seen on X-rays. These spots are typically found at the ends of long bones, in the sternum, and in the pelvis.

The symptoms of chondrodysplasia punctata can vary widely depending on the specific type of the disorder. Some people with the condition may have short stature, bowed legs, and other skeletal abnormalities, while others may have only mild symptoms or no symptoms at all. The condition can also be associated with developmental delays, intellectual disability, and other health problems.

There are several different types of chondrodysplasia punctata, each caused by a different genetic mutation. Some forms of the disorder are inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene (one from each parent) in order to develop the condition. Other forms of chondrodysplasia punctata are inherited in an X-linked dominant manner, meaning that a single copy of the mutated gene (on the X chromosome) is enough to cause the disorder in females. Males, who have only one X chromosome, will typically be more severely affected by X-linked dominant disorders.

There is no cure for chondrodysplasia punctata, and treatment is focused on managing the symptoms of the condition. This may include physical therapy, bracing or surgery to correct skeletal abnormalities, and medications to manage pain or other health problems.

The cornea is the clear, dome-shaped surface at the front of the eye. It plays a crucial role in focusing vision. The cornea protects the eye from harmful particles and microorganisms, and it also serves as a barrier against UV light. Its transparency allows light to pass through and get focused onto the retina. The cornea does not contain blood vessels, so it relies on tears and the fluid inside the eye (aqueous humor) for nutrition and oxygen. Any damage or disease that affects its clarity and shape can significantly impact vision and potentially lead to blindness if left untreated.

"Ocular physiological phenomena" is not a standardized medical term with a specific definition. However, I can provide some examples of ocular physiological phenomena, which refer to various normal functions and processes that occur in the eye. Here are a few examples:

1. Accommodation: The ability of the eye to change optical power to maintain a clear image or focus on an object as its distance varies. This is primarily achieved by changing the curvature of the lens through the action of the ciliary muscles.
2. Pupillary reflex: The automatic adjustment of the pupil's size in response to changes in light intensity. In bright light, the pupil constricts (miosis), while in dim light, it dilates (mydriasis). This reflex helps regulate the amount of light that enters the eye.
3. Tear production: The continuous secretion of tears by the lacrimal glands to keep the eyes moist and protected from dust, microorganisms, and other foreign particles.
4. Extraocular muscle function: The coordinated movement of the six extraocular muscles that control eyeball rotation and enable various gaze directions.
5. Color vision: The ability to perceive and distinguish different colors based on the sensitivity of photoreceptor cells (cones) in the retina to specific wavelengths of light.
6. Dark adaptation: The process by which the eyes adjust to low-light conditions, improving visual sensitivity primarily through changes in the rod photoreceptors' sensitivity and pupil dilation.
7. Light adaptation: The ability of the eye to adjust to different levels of illumination, mainly through alterations in pupil size and photoreceptor cell response.

These are just a few examples of ocular physiological phenomena. There are many more processes and functions that occur within the eye, contributing to our visual perception and overall eye health.

The fovea centralis, also known as the macula lutea, is a small pit or depression located in the center of the retina, an light-sensitive tissue at the back of the eye. It is responsible for sharp, detailed vision (central vision) and color perception. The fovea contains only cones, the photoreceptor cells that are responsible for color vision and high visual acuity. It has a higher concentration of cones than any other area in the retina, allowing it to provide the greatest detail and color discrimination. The center of the fovea is called the foveola, which contains the highest density of cones and is avascular, meaning it lacks blood vessels to avoid interfering with the light passing through to the photoreceptor cells.

Eye injuries refer to any damage or trauma caused to the eye or its surrounding structures. These injuries can vary in severity and may include:

1. Corneal abrasions: A scratch or scrape on the clear surface of the eye (cornea).
2. Chemical burns: Occurs when chemicals come into contact with the eye, causing damage to the cornea and other structures.
3. Eyelid lacerations: Cuts or tears to the eyelid.
4. Subconjunctival hemorrhage: Bleeding under the conjunctiva, the clear membrane that covers the white part of the eye.
5. Hyphema: Accumulation of blood in the anterior chamber of the eye, which is the space between the cornea and iris.
6. Orbital fractures: Breaks in the bones surrounding the eye.
7. Retinal detachment: Separation of the retina from its underlying tissue, which can lead to vision loss if not treated promptly.
8. Traumatic uveitis: Inflammation of the uvea, the middle layer of the eye, caused by trauma.
9. Optic nerve damage: Damage to the optic nerve, which transmits visual information from the eye to the brain.

Eye injuries can result from a variety of causes, including accidents, sports-related injuries, violence, and chemical exposure. It is important to seek medical attention promptly for any suspected eye injury to prevent further damage and potential vision loss.

I'm sorry for any confusion, but "hair color" is not a term that has a medical definition in the same way that a term like "myocardial infarction" (heart attack) does. Hair color can be described in various ways, such as being a natural hair color (like blonde, brunette, red, or black) or describing a change in hair color due to factors like aging (gray or white hairs) or hair dye usage.

However, it's worth noting that changes in hair color can sometimes be associated with certain medical conditions. For example, premature graying of the hair before the age of 30 can be a feature of certain genetic disorders or vitamin B12 deficiency. Similarly, some skin conditions like alopecia areata or vitiligo can cause patchy changes in hair color. But these associations don't provide a medical definition for 'hair color'.

Refractive errors are a group of vision conditions that include nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. These conditions occur when the shape of the eye prevents light from focusing directly on the retina, causing blurred or distorted vision.

Myopia is a condition where distant objects appear blurry while close-up objects are clear. This occurs when the eye is too long or the cornea is too curved, causing light to focus in front of the retina instead of directly on it.

Hyperopia, on the other hand, is a condition where close-up objects appear blurry while distant objects are clear. This happens when the eye is too short or the cornea is not curved enough, causing light to focus behind the retina.

Astigmatism is a condition that causes blurred vision at all distances due to an irregularly shaped cornea or lens.

Presbyopia is a natural aging process that affects everyone as they get older, usually around the age of 40. It causes difficulty focusing on close-up objects and can be corrected with reading glasses, bifocals, or progressive lenses.

Refractive errors can be diagnosed through a comprehensive eye exam and are typically corrected with eyeglasses, contact lenses, or refractive surgery such as LASIK.

The optic chiasm is a structure in the brain where the optic nerves from each eye meet and cross. This allows for the integration of visual information from both eyes into the brain's visual cortex, creating a single, combined image of the visual world. The optic chiasm plays an important role in the processing of visual information and helps to facilitate depth perception and other complex visual tasks. Damage to the optic chiasm can result in various visual field deficits, such as bitemporal hemianopsia, where there is a loss of vision in the outer halves (temporal fields) of both eyes' visual fields.

Intraocular pressure (IOP) is the fluid pressure within the eye, specifically within the anterior chamber, which is the space between the cornea and the iris. It is measured in millimeters of mercury (mmHg). The aqueous humor, a clear fluid that fills the anterior chamber, is constantly produced and drained, maintaining a balance that determines the IOP. Normal IOP ranges from 10-21 mmHg, with average values around 15-16 mmHg. Elevated IOP is a key risk factor for glaucoma, a group of eye conditions that can lead to optic nerve damage and vision loss if not treated promptly and effectively. Regular monitoring of IOP is essential in diagnosing and managing glaucoma and other ocular health issues.

Ocular tuberculosis (OTB) is a form of extrapulmonary tuberculosis (TB), which results from the spread of Mycobacterium tuberculosis complex bacteria outside the lungs. In ocular tuberculosis, these bacteria primarily affect the eye and its surrounding structures.

The most common form of OTB is tubercular uveitis, which involves inflammation of the uveal tract (iris, ciliary body, and choroid). Other forms of OTB include:

* Tubercular conjunctivitis: Inflammation of the conjunctiva, the mucous membrane that covers the front part of the eye and lines the inside of the eyelids.
* Tubercular keratitis: Inflammation of the cornea, the transparent outer layer at the front of the eye.
* Tubercular scleritis: Inflammation of the sclera, the white protective coating of the eye.
* Tubercular episcleritis: Inflammation of the episclera, a thin layer of tissue between the conjunctiva and sclera.
* Tubercular dacryoadenitis: Inflammation of the lacrimal gland, which produces tears.
* Tubercular optic neuritis: Inflammation of the optic nerve, which transmits visual information from the eye to the brain.

Diagnosis of OTB can be challenging due to its varied clinical presentations and the need for laboratory confirmation. A definitive diagnosis typically requires the isolation of Mycobacterium tuberculosis from ocular tissues or fluids, which may involve invasive procedures. In some cases, a presumptive diagnosis might be made based on clinical findings, epidemiological data, and response to anti-tuberculous therapy.

Treatment for OTB usually involves a standard anti-tuberculosis regimen consisting of multiple drugs (isoniazid, rifampin, ethambutol, and pyrazinamide) for at least six months. Corticosteroids or other immunosuppressive agents might be used concomitantly to manage inflammation and prevent tissue damage. Close monitoring is essential to ensure treatment adherence, assess response to therapy, and detect potential side effects.

Membrane glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide backbone. They are integral components of biological membranes, spanning the lipid bilayer and playing crucial roles in various cellular processes.

The glycosylation of these proteins occurs in the endoplasmic reticulum (ER) and Golgi apparatus during protein folding and trafficking. The attached glycans can vary in structure, length, and composition, which contributes to the diversity of membrane glycoproteins.

Membrane glycoproteins can be classified into two main types based on their orientation within the lipid bilayer:

1. Type I (N-linked): These glycoproteins have a single transmembrane domain and an extracellular N-terminus, where the oligosaccharides are predominantly attached via asparagine residues (Asn-X-Ser/Thr sequon).
2. Type II (C-linked): These glycoproteins possess two transmembrane domains and an intracellular C-terminus, with the oligosaccharides linked to tryptophan residues via a mannose moiety.

Membrane glycoproteins are involved in various cellular functions, such as:

* Cell adhesion and recognition
* Receptor-mediated signal transduction
* Enzymatic catalysis
* Transport of molecules across membranes
* Cell-cell communication
* Immunological responses

Some examples of membrane glycoproteins include cell surface receptors (e.g., growth factor receptors, cytokine receptors), adhesion molecules (e.g., integrins, cadherins), and transporters (e.g., ion channels, ABC transporters).

In medical terms, "tears" are a clear, salty liquid that is produced by the tear glands (lacrimal glands) in our eyes. They serve to keep the eyes moist, protect against dust and other foreign particles, and help to provide clear vision by maintaining a smooth surface on the front of the eye. Tears consist of water, oil, and mucus, which help to prevent evaporation and ensure that the tears spread evenly across the surface of the eye. Emotional or reflexive responses, such as crying or yawning, can also stimulate the production of tears.

Ocular vision refers to the ability to process and interpret visual information that is received by the eyes. This includes the ability to see clearly and make sense of the shapes, colors, and movements of objects in the environment. The ocular system, which includes the eye and related structures such as the optic nerve and visual cortex of the brain, works together to enable vision.

There are several components of ocular vision, including:

* Visual acuity: the clarity or sharpness of vision
* Field of vision: the extent of the visual world that is visible at any given moment
* Color vision: the ability to distinguish different colors
* Depth perception: the ability to judge the distance of objects in three-dimensional space
* Contrast sensitivity: the ability to distinguish an object from its background based on differences in contrast

Disorders of ocular vision can include refractive errors such as nearsightedness or farsightedness, as well as more serious conditions such as cataracts, glaucoma, and macular degeneration. These conditions can affect one or more aspects of ocular vision and may require medical treatment to prevent further vision loss.

Strabismus is a condition of the ocular muscles where the eyes are not aligned properly and point in different directions. One eye may turn inward, outward, upward, or downward while the other one remains fixed and aligns normally. This misalignment can occur occasionally or constantly. Strabismus is also commonly referred to as crossed eyes or walleye. The condition can lead to visual impairments such as amblyopia (lazy eye) and depth perception problems if not treated promptly and effectively, usually through surgery, glasses, or vision therapy.

Iris diseases refer to a variety of conditions that affect the iris, which is the colored part of the eye that regulates the amount of light reaching the retina by adjusting the size of the pupil. Some common iris diseases include:

1. Iritis: This is an inflammation of the iris and the adjacent tissues in the eye. It can cause pain, redness, photophobia (sensitivity to light), and blurred vision.
2. Aniridia: A congenital condition characterized by the absence or underdevelopment of the iris. This can lead to decreased visual acuity, sensitivity to light, and an increased risk of glaucoma.
3. Iris cysts: These are fluid-filled sacs that form on the iris. They are usually benign but can cause vision problems if they grow too large or interfere with the function of the eye.
4. Iris melanoma: A rare type of eye cancer that develops in the pigmented cells of the iris. It can cause symptoms such as blurred vision, floaters, and changes in the appearance of the iris.
5. Iridocorneal endothelial syndrome (ICE): A group of rare eye conditions that affect the cornea and the iris. They are characterized by the growth of abnormal tissue on the back surface of the cornea and can lead to vision loss.

It is important to seek medical attention if you experience any symptoms of iris diseases, as early diagnosis and treatment can help prevent complications and preserve your vision.

Ophthalmic solutions are sterile, single-use or multi-dose preparations in a liquid form that are intended for topical administration to the eye. These solutions can contain various types of medications, such as antibiotics, anti-inflammatory agents, antihistamines, or lubricants, which are used to treat or prevent ocular diseases and conditions.

The pH and osmolarity of ophthalmic solutions are carefully controlled to match the physiological environment of the eye and minimize any potential discomfort or irritation. The solutions may be packaged in various forms, including drops, sprays, or irrigations, depending on the intended use and administration route.

It is important to follow the instructions for use provided by a healthcare professional when administering ophthalmic solutions, as improper use can lead to eye injury or reduced effectiveness of the medication.

Platelet Storage Pool Deficiency (PSPD) is a group of bleeding disorders characterized by a decrease in the number or function of secretory granules (storage pools) in platelets, which are small blood cells that play a crucial role in clotting. These granules contain various substances such as ADP (adenosine diphosphate), ATP (adenosine triphosphate), calcium ions, and serotonin, which are released during platelet activation to help promote clot formation.

In PSPD, the quantitative or qualitative deficiency of these granules leads to impaired platelet function and increased bleeding tendency. The condition can be inherited or acquired, and it is often classified based on the type of granule affected: dense granules (delta granules) or alpha granules.

Delta granule deficiency, also known as Dense Granule Deficiency (DGD), results in decreased levels of ADP, ATP, and calcium ions, while alpha granule deficiency leads to reduced levels of von Willebrand factor, fibrinogen, and other clotting factors.

Symptoms of PSPD can vary from mild to severe and may include easy bruising, prolonged bleeding after injury or surgery, nosebleeds, and gum bleeding. The diagnosis typically involves platelet function tests, electron microscopy, and genetic testing. Treatment options depend on the severity of the condition and may include desmopressin (DDAVP), platelet transfusions, or other medications to manage bleeding symptoms.

Ichthyosis is a group of skin disorders that are characterized by dry, thickened, scaly skin. The name "ichthyosis" comes from the Greek word "ichthys," which means fish, as the skin can have a fish-like scale appearance. These conditions can be inherited or acquired and vary in severity.

The medical definition of ichthyosis is a heterogeneous group of genetic keratinization disorders that result in dry, thickened, and scaly skin. The condition may affect any part of the body, but it most commonly appears on the extremities, scalp, and trunk. Ichthyosis can also have associated symptoms such as redness, itching, and blistering.

The severity of ichthyosis can range from mild to severe, and some forms of the condition may be life-threatening in infancy. The exact symptoms and their severity depend on the specific type of ichthyosis a person has. Treatment for ichthyosis typically involves moisturizing the skin, avoiding irritants, and using medications to help control scaling and inflammation.

Kallmann Syndrome is a genetic condition that is characterized by hypogonadotropic hypogonadism (reduced or absent function of the gonads (ovaries or testes) due to deficient secretion of pituitary gonadotropins) and anosmia or hyposmia (reduced or absent sense of smell). It is caused by abnormal migration of neurons that produce gonadotropin-releasing hormone (GnRH) during fetal development, which results in decreased production of sex hormones and delayed or absent puberty.

Kallmann Syndrome can also be associated with other symptoms such as color vision deficiency, hearing loss, renal agenesis, and neurological defects. It is typically inherited in an autosomal dominant or X-linked recessive pattern, and diagnosis usually involves a combination of clinical evaluation, hormonal testing, and genetic analysis. Treatment may include hormone replacement therapy to induce puberty and maintain sexual function, as well as management of associated symptoms.

I'm sorry for any confusion, but "Guinea" is not a medical term. It is a geographical term referring to a region on the west coast of Africa, as well as the country of Equatorial Guinea and its neighboring countries. Additionally, "Guinea" can also refer to a unit of currency in Liberia.

If you have any medical concerns or questions, I would be happy to try to help answer them for you.

Visual pathways, also known as the visual system or the optic pathway, refer to the series of specialized neurons in the nervous system that transmit visual information from the eyes to the brain. This complex network includes the retina, optic nerve, optic chiasma, optic tract, lateral geniculate nucleus, pulvinar, and the primary and secondary visual cortices located in the occipital lobe of the brain.

The process begins when light enters the eye and strikes the photoreceptor cells (rods and cones) in the retina, converting the light energy into electrical signals. These signals are then transmitted to bipolar cells and subsequently to ganglion cells, whose axons form the optic nerve. The fibers from each eye's nasal hemiretina cross at the optic chiasma, while those from the temporal hemiretina continue without crossing. This results in the formation of the optic tract, which carries visual information from both eyes to the opposite side of the brain.

The majority of fibers in the optic tract synapse with neurons in the lateral geniculate nucleus (LGN), a part of the thalamus. The LGN sends this information to the primary visual cortex, also known as V1 or Brodmann area 17, located in the occipital lobe. Here, simple features like lines and edges are initially processed. Further processing occurs in secondary (V2) and tertiary (V3-V5) visual cortices, where more complex features such as shape, motion, and depth are analyzed. Ultimately, this information is integrated to form our perception of the visual world.

The optic nerve, also known as the second cranial nerve, is the nerve that transmits visual information from the retina to the brain. It is composed of approximately one million nerve fibers that carry signals related to vision, such as light intensity and color, from the eye's photoreceptor cells (rods and cones) to the visual cortex in the brain. The optic nerve is responsible for carrying this visual information so that it can be processed and interpreted by the brain, allowing us to see and perceive our surroundings. Damage to the optic nerve can result in vision loss or impairment.

The retina is the innermost, light-sensitive layer of tissue in the eye of many vertebrates and some cephalopods. It receives light that has been focused by the cornea and lens, converts it into neural signals, and sends these to the brain via the optic nerve. The retina contains several types of photoreceptor cells including rods (which handle vision in low light) and cones (which are active in bright light and are capable of color vision).

In medical terms, any pathological changes or diseases affecting the retinal structure and function can lead to visual impairment or blindness. Examples include age-related macular degeneration, diabetic retinopathy, retinal detachment, and retinitis pigmentosa among others.

Prader-Willi Syndrome (PWS) is a genetic disorder that affects several parts of the body and is characterized by a range of symptoms including:

1. Developmental delays and intellectual disability.
2. Hypotonia (low muscle tone) at birth, which can lead to feeding difficulties in infancy.
3. Excessive appetite and obesity, typically beginning around age 2, due to a persistent hunger drive and decreased satiety.
4. Behavioral problems such as temper tantrums, stubbornness, and compulsive behaviors.
5. Hormonal imbalances leading to short stature, small hands and feet, incomplete sexual development, and decreased bone density.
6. Distinctive facial features including a thin upper lip, almond-shaped eyes, and a narrowed forehead.
7. Sleep disturbances such as sleep apnea or excessive daytime sleepiness.

PWS is caused by the absence of certain genetic material on chromosome 15, which results in abnormal gene function. It affects both males and females equally and has an estimated incidence of 1 in 10,000 to 30,000 live births. Early diagnosis and management can help improve outcomes for individuals with PWS.

Parasitic eye infections are conditions characterized by the invasion and infestation of the eye or its surrounding structures by parasites. These can be protozoans, helminths, or ectoparasites. Examples of such infections include Acanthamoeba keratitis, which is caused by a free-living amoeba found in water and soil; Toxoplasmosis, which is caused by the protozoan Toxoplasma gondii; Loiasis, which is caused by the parasitic filarial worm Loa loa; and Demodicosis, which is caused by the mite Demodex folliculorum. Symptoms can vary depending on the type of parasite but often include redness, pain, discharge, and vision changes. Treatment typically involves antiparasitic medications and sometimes surgery to remove the parasites or damaged tissue. Prevention measures include good hygiene practices and avoiding contact with contaminated water or soil.

I'm sorry for any confusion, but "Puerto Rico" is not a medical term. It is a territorial possession of the United States, located in the northeastern Caribbean Sea. It includes the main island of Puerto Rico and various smaller islands. If you have any questions about a medical topic, please provide more details so I can try to help answer your question.

A melanocortin receptor (MCR) is a type of G protein-coupled receptor that binds melanocortin peptides. The melanocortin-1 receptor (MC1R) is one of five known subtypes of MCRs (MC1R-MC5R).

The MC1R is primarily expressed in melanocytes, which are pigment-producing cells located in the skin, hair follicles, and eyes. This receptor plays a crucial role in determining the type of melanin that is produced in response to environmental stimuli such as UV radiation.

Activation of the MC1R by its endogenous ligands, including α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotropic hormone (ACTH), leads to the activation of adenylate cyclase and an increase in intracellular cAMP levels. This results in the activation of protein kinase A and the phosphorylation of key transcription factors, which ultimately promote the expression of genes involved in melanin synthesis.

Mutations in the MC1R gene have been associated with various pigmentation disorders, including red hair color, fair skin, and an increased risk of developing skin cancer. Additionally, polymorphisms in the MC1R gene have been linked to an increased risk of developing other diseases such as obesity and type 2 diabetes.

Recessive genes refer to the alleles (versions of a gene) that will only be expressed when an individual has two copies of that particular allele, one inherited from each parent. If an individual inherits one recessive allele and one dominant allele for a particular gene, the dominant allele will be expressed and the recessive allele will have no effect on the individual's phenotype (observable traits).

Recessive genes can still play a role in determining an individual's genetic makeup and can be passed down through generations even if they are not expressed. If two carriers of a recessive gene have children, there is a 25% chance that their offspring will inherit two copies of the recessive allele and exhibit the associated recessive trait.

Examples of genetic disorders caused by recessive genes include cystic fibrosis, sickle cell anemia, and albinism.

Conjunctival diseases refer to a group of medical conditions that affect the conjunctiva, which is the thin, clear mucous membrane that covers the inner surface of the eyelids and the white part of the eye (known as the sclera). The conjunctiva helps to keep the eye moist and protected from irritants.

Conjunctival diseases can cause a range of symptoms, including redness, itching, burning, discharge, grittiness, and pain. Some common conjunctival diseases include:

1. Conjunctivitis (pink eye): This is an inflammation or infection of the conjunctiva that can be caused by viruses, bacteria, or allergies. Symptoms may include redness, itching, discharge, and watery eyes.
2. Pinguecula: This is a yellowish, raised bump that forms on the conjunctiva, usually near the corner of the eye. It is caused by an overgrowth of connective tissue and may be related to sun exposure or dry eye.
3. Pterygium: This is a fleshy growth that extends from the conjunctiva onto the cornea (the clear front part of the eye). It can cause redness, irritation, and vision problems if it grows large enough to cover the pupil.
4. Allergic conjunctivitis: This is an inflammation of the conjunctiva caused by an allergic reaction to substances such as pollen, dust mites, or pet dander. Symptoms may include redness, itching, watery eyes, and swelling.
5. Chemical conjunctivitis: This is an irritation or inflammation of the conjunctiva caused by exposure to chemicals such as chlorine, smoke, or fumes. Symptoms may include redness, burning, and tearing.
6. Giant papillary conjunctivitis (GPC): This is a type of allergic reaction that occurs in response to the presence of a foreign body in the eye, such as a contact lens. Symptoms may include itching, mucus discharge, and a gritty feeling in the eye.

Treatment for conjunctival diseases depends on the underlying cause. In some cases, over-the-counter medications or home remedies may be sufficient to relieve symptoms. However, more severe cases may require prescription medication or medical intervention. It is important to consult with a healthcare provider if you experience persistent or worsening symptoms of conjunctival disease.

Eye infections, also known as ocular infections, are conditions characterized by the invasion and multiplication of pathogenic microorganisms in any part of the eye or its surrounding structures. These infections can affect various parts of the eye, including the conjunctiva (conjunctivitis), cornea (keratitis), eyelid (blepharitis), or the internal structures of the eye (endophthalmitis, uveitis). The symptoms may include redness, pain, discharge, itching, blurred vision, and sensitivity to light. The cause can be bacterial, viral, fungal, or parasitic, and the treatment typically involves antibiotics, antivirals, or antifungals, depending on the underlying cause.

Uveitis is the inflammation of the uvea, the middle layer of the eye between the retina and the white of the eye (sclera). The uvea consists of the iris, ciliary body, and choroid. Uveitis can cause redness, pain, and vision loss. It can be caused by various systemic diseases, infections, or trauma. Depending on the part of the uvea that's affected, uveitis can be classified as anterior (iritis), intermediate (cyclitis), posterior (choroiditis), or pan-uveitis (affecting all layers). Treatment typically includes corticosteroids and other immunosuppressive drugs to control inflammation.

Melanophores are specialized pigment-containing cells found in various organisms, including vertebrates and some invertebrates. In humans and other mammals, melanophores are primarily located within the skin's dermal layer and are part of the larger group of chromatophores.

Melanophores contain melanosomes, which are organelles that store and transport the pigment melanin. These cells play a crucial role in determining the coloration of an individual's skin, hair, and eyes by producing, storing, and distributing melanin granules within their cytoplasm.

In response to hormonal signals or neural stimulation, melanophores can undergo changes in the distribution of melanosomes, leading to variations in color intensity. This process is known as melanin dispersion or aggregation and is responsible for various physiological responses, such as skin tanning upon exposure to sunlight or the color-changing abilities observed in some animals like chameleons and cuttlefish.

It's important to note that while humans do not have the ability to change their skin color rapidly like some other animals, melanophores still play a significant role in protecting our skin from harmful ultraviolet radiation by producing melanin, which helps absorb and dissipate this energy, reducing damage to skin cells.

Dry eye syndrome, also known as keratoconjunctivitis sicca, is a condition characterized by insufficient lubrication and moisture of the eyes. This occurs when the tears produced by the eyes are not sufficient in quantity or quality to keep the eyes moist and comfortable. The medical definition of dry eye syndromes includes the following symptoms:

1. A gritty or sandy sensation in the eyes
2. Burning or stinging sensations
3. Redness and irritation
4. Blurred vision that improves with blinking
5. Light sensitivity
6. A feeling of something foreign in the eye
7. Stringy mucus in or around the eyes
8. Difficulty wearing contact lenses
9. Watery eyes, which may seem contradictory but can be a response to dryness
10. Eye fatigue and discomfort after prolonged screen time or reading

The causes of dry eye syndromes can include aging, hormonal changes, certain medical conditions (such as diabetes, rheumatoid arthritis, lupus, Sjogren's syndrome), medications (antihistamines, decongestants, antidepressants, birth control pills), environmental factors (dry air, wind, smoke, dust), and prolonged screen time or reading.

Treatment for dry eye syndromes depends on the severity of the condition and its underlying causes. It may include artificial tears, lifestyle changes, prescription medications, and in some cases, surgical procedures to improve tear production or drainage.

A phenotype is the physical or biochemical expression of an organism's genes, or the observable traits and characteristics resulting from the interaction of its genetic constitution (genotype) with environmental factors. These characteristics can include appearance, development, behavior, and resistance to disease, among others. Phenotypes can vary widely, even among individuals with identical genotypes, due to differences in environmental influences, gene expression, and genetic interactions.

Sunscreening agents, also known as sunscreens or sunblocks, are substances that protect the skin from the harmful effects of ultraviolet (UV) radiation from the sun. They work by absorbing, reflecting, or scattering UV radiation, preventing it from reaching the skin and causing damage such as sunburn, premature aging, and skin cancer.

Sunscreening agents can be chemical or physical. Chemical sunscreens contain organic compounds that absorb UV radiation and convert it into heat, which is then released from the skin. Examples of chemical sunscreens include oxybenzone, avobenzone, octinoxate, and homosalate.

Physical sunscreens, on the other hand, contain inorganic compounds that reflect or scatter UV radiation away from the skin. The most common physical sunscreen agents are zinc oxide and titanium dioxide.

Sunscreening agents are usually formulated into creams, lotions, gels, sprays, or sticks and are applied to the skin before sun exposure. They should be reapplied every two hours or after swimming, sweating, or toweling off to ensure continued protection. It is recommended to use a broad-spectrum sunscreen with an SPF (Sun Protection Factor) of at least 30, which blocks both UVA and UVB radiation.

Conjunctivitis is an inflammation or infection of the conjunctiva, a thin, clear membrane that covers the inner surface of the eyelids and the outer surface of the eye. The condition can cause redness, itching, burning, tearing, discomfort, and a gritty feeling in the eyes. It can also result in a discharge that can be clear, yellow, or greenish.

Conjunctivitis can have various causes, including bacterial or viral infections, allergies, irritants (such as smoke, chlorine, or contact lens solutions), and underlying medical conditions (like dry eye or autoimmune disorders). Treatment depends on the cause of the condition but may include antibiotics, antihistamines, anti-inflammatory medications, or warm compresses.

It is essential to maintain good hygiene practices, like washing hands frequently and avoiding touching or rubbing the eyes, to prevent spreading conjunctivitis to others. If you suspect you have conjunctivitis, it's recommended that you consult an eye care professional for a proper diagnosis and treatment plan.

Ocular hypotension is a medical term that refers to a condition where the pressure inside the eye (intraocular pressure or IOP) is lower than normal. The normal range for IOP is typically between 10-21 mmHg (millimeters of mercury). Ocular hypotension can occur due to various reasons, including certain medications, medical conditions, or surgical procedures that affect the eye's ability to produce or drain aqueous humor, the clear fluid inside the eye.

While mild ocular hypotension may not cause any symptoms, more significant cases can lead to complications such as decreased vision, optic nerve damage, and visual field loss. If left untreated, it could potentially result in a condition called glaucoma. It is essential to consult an eye care professional if you suspect ocular hypotension or experience any changes in your vision.

Oxidoreductases are a class of enzymes that catalyze oxidation-reduction reactions, which involve the transfer of electrons from one molecule (the reductant) to another (the oxidant). These enzymes play a crucial role in various biological processes, including energy production, metabolism, and detoxification.

The oxidoreductase-catalyzed reaction typically involves the donation of electrons from a reducing agent (donor) to an oxidizing agent (acceptor), often through the transfer of hydrogen atoms or hydride ions. The enzyme itself does not undergo any permanent chemical change during this process, but rather acts as a catalyst to lower the activation energy required for the reaction to occur.

Oxidoreductases are classified and named based on the type of electron donor or acceptor involved in the reaction. For example, oxidoreductases that act on the CH-OH group of donors are called dehydrogenases, while those that act on the aldehyde or ketone groups are called oxidases. Other examples include reductases, peroxidases, and catalases.

Understanding the function and regulation of oxidoreductases is important for understanding various physiological processes and developing therapeutic strategies for diseases associated with impaired redox homeostasis, such as cancer, neurodegenerative disorders, and cardiovascular disease.

I'm sorry for any confusion, but "Zimbabwe" is not a medical term. It's a country located in the southern part of Africa. If you have any questions about medical terms or concepts, I'd be happy to help answer those for you!

Adaptor Protein Complex (AP) beta subunits are structural proteins that play a crucial role in intracellular vesicle trafficking. They are part of the heterotetrameric AP complex, which is responsible for recognizing and binding to specific sorting signals on membrane cargo proteins, allowing for their packaging into transport vesicles.

There are four different types of AP complexes (AP-1, AP-2, AP-3, and AP-4), each with a unique set of subunits that confer specific functions. The beta subunit is a common component of all four complexes and is essential for their stability and function.

The beta subunit interacts with other subunits within the AP complex as well as with accessory proteins, such as clathrin, to form a coat around the transport vesicle. This coat helps to shape the vesicle and facilitate its movement between different cellular compartments.

Mutations in genes encoding AP beta subunits have been linked to various human diseases, including forms of hemolytic anemia, neurological disorders, and immunodeficiency.

The vitreous body, also known simply as the vitreous, is the clear, gel-like substance that fills the space between the lens and the retina in the eye. It is composed mainly of water, but also contains collagen fibers, hyaluronic acid, and other proteins. The vitreous helps to maintain the shape of the eye and provides a transparent medium for light to pass through to reach the retina. With age, the vitreous can become more liquefied and may eventually separate from the retina, leading to symptoms such as floaters or flashes of light.

Electroretinography (ERG) is a medical test used to evaluate the functioning of the retina, which is the light-sensitive tissue located at the back of the eye. The test measures the electrical responses of the retina to light stimulation.

During the procedure, a special contact lens or electrode is placed on the surface of the eye to record the electrical activity generated by the retina's light-sensitive cells (rods and cones) and other cells in the retina. The test typically involves presenting different levels of flashes of light to the eye while the electrical responses are recorded.

The resulting ERG waveform provides information about the overall health and function of the retina, including the condition of the photoreceptors, the integrity of the inner retinal layers, and the health of the retinal ganglion cells. This test is often used to diagnose and monitor various retinal disorders, such as retinitis pigmentosa, macular degeneration, and diabetic retinopathy.

Eye movements, also known as ocular motility, refer to the voluntary or involuntary motion of the eyes that allows for visual exploration of our environment. There are several types of eye movements, including:

1. Saccades: rapid, ballistic movements that quickly shift the gaze from one point to another.
2. Pursuits: smooth, slow movements that allow the eyes to follow a moving object.
3. Vergences: coordinated movements of both eyes in opposite directions, usually in response to a three-dimensional stimulus.
4. Vestibulo-ocular reflex (VOR): automatic eye movements that help stabilize the gaze during head movement.
5. Optokinetic nystagmus (OKN): rhythmic eye movements that occur in response to large moving visual patterns, such as when looking out of a moving vehicle.

Abnormalities in eye movements can indicate neurological or ophthalmological disorders and are often assessed during clinical examinations.

DNA Mutational Analysis is a laboratory test used to identify genetic variations or changes (mutations) in the DNA sequence of a gene. This type of analysis can be used to diagnose genetic disorders, predict the risk of developing certain diseases, determine the most effective treatment for cancer, or assess the likelihood of passing on an inherited condition to offspring.

The test involves extracting DNA from a patient's sample (such as blood, saliva, or tissue), amplifying specific regions of interest using polymerase chain reaction (PCR), and then sequencing those regions to determine the precise order of nucleotide bases in the DNA molecule. The resulting sequence is then compared to reference sequences to identify any variations or mutations that may be present.

DNA Mutational Analysis can detect a wide range of genetic changes, including single-nucleotide polymorphisms (SNPs), insertions, deletions, duplications, and rearrangements. The test is often used in conjunction with other diagnostic tests and clinical evaluations to provide a comprehensive assessment of a patient's genetic profile.

It is important to note that not all mutations are pathogenic or associated with disease, and the interpretation of DNA Mutational Analysis results requires careful consideration of the patient's medical history, family history, and other relevant factors.

Sunburn is a cutaneous condition characterized by redness, pain, and sometimes swelling of the skin caused by overexposure to ultraviolet (UV) radiation from the sun or other sources such as tanning beds. The skin may also blister and peel in severe cases. Sunburn is essentially a burn to the skin that can have both immediate and long-term consequences, including increased aging of the skin and an increased risk of skin cancer. It is important to protect the skin from excessive sun exposure by using sunscreen, wearing protective clothing, and seeking shade during peak sunlight hours.

Hemorrhagic disorders are medical conditions characterized by abnormal bleeding due to impaired blood clotting. This can result from deficiencies in coagulation factors, platelet dysfunction, or the use of medications that interfere with normal clotting processes. Examples include hemophilia, von Willebrand disease, and disseminated intravascular coagulation (DIC). Treatment often involves replacing the missing clotting factor or administering medications to help control bleeding.

The macula lutea, often simply referred to as the macula or fovea centralis, is a part of the eye that is responsible for central vision and color perception. It's located in the center of the retina, the light-sensitive tissue at the back of the eye. The macula contains a high concentration of pigments called xanthophylls, which give it a yellowish color and protect the photoreceptor cells in this area from damage by blue light.

The central part of the macula is called the fovea, which is a small depression that contains only cones, the photoreceptor cells responsible for color vision and high visual acuity. The fovea is surrounded by the parafovea and the perifovea, which contain both cones and rods, the photoreceptor cells responsible for low-light vision and peripheral vision.

Damage to the macula can result in a loss of central vision and color perception, a condition known as age-related macular degeneration (AMD), which is a leading cause of blindness in older adults. Other conditions that can affect the macula include macular edema, macular holes, and macular pucker.

Corneal diseases are a group of disorders that affect the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays an important role in focusing vision, and any damage or disease can cause significant visual impairment or loss. Some common types of corneal diseases include:

1. Keratoconus: A progressive disorder in which the cornea thins and bulges outward into a cone shape, causing distorted vision.
2. Fuchs' dystrophy: A genetic disorder that affects the inner layer of the cornea called the endothelium, leading to swelling, cloudiness, and decreased vision.
3. Dry eye syndrome: A condition in which the eyes do not produce enough tears or the tears evaporate too quickly, causing discomfort, redness, and blurred vision.
4. Corneal ulcers: Open sores on the cornea that can be caused by infection, trauma, or other factors.
5. Herpes simplex keratitis: A viral infection of the cornea that can cause recurrent episodes of inflammation, scarring, and vision loss.
6. Corneal dystrophies: Inherited disorders that affect the structure and clarity of the cornea, leading to visual impairment or blindness.
7. Bullous keratopathy: A condition in which the endothelium fails to pump fluid out of the cornea, causing it to swell and form blisters.
8. Corneal trauma: Injury to the cornea caused by foreign objects, chemicals, or other factors that can lead to scarring, infection, and vision loss.

Treatment for corneal diseases varies depending on the specific condition and severity of the disease. Options may include eyedrops, medications, laser surgery, corneal transplantation, or other treatments.

Aqueous humor is a clear, watery fluid that fills the anterior and posterior chambers of the eye. It is produced by the ciliary processes in the posterior chamber and circulates through the pupil into the anterior chamber, where it provides nutrients to the cornea and lens, maintains intraocular pressure, and helps to shape the eye. The aqueous humor then drains out of the eye through the trabecular meshwork and into the canal of Schlemm, eventually reaching the venous system.

Ceroid is a term used in pathology to describe a type of inclusion body that can be found in various tissues and cells in the body. These inclusions are composed of a protein called alpha-synuclein that has become aggregated and tangled, as well as lipids and other substances. Ceroids are often seen in neurons, but they can also be found in other types of cells such as glial cells.

Ceroid deposits are associated with several neurodegenerative disorders, including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. These conditions are characterized by the accumulation of abnormal protein aggregates in the brain, which can lead to neuronal dysfunction and death. The exact role that ceroids play in these diseases is not fully understood, but they are thought to contribute to the toxicity and degeneration of nerve cells.

It's worth noting that ceroid is sometimes used interchangeably with other terms such as "lipofuscin" or "age pigment," although there are some differences between these substances at a molecular level. Nonetheless, they all refer to the accumulation of lipid-rich inclusion bodies in cells and tissues over time.

A nonsense codon is a sequence of three nucleotides in DNA or RNA that does not code for an amino acid. Instead, it signals the end of the protein-coding region of a gene and triggers the termination of translation, the process by which the genetic code is translated into a protein.

In DNA, the nonsense codons are UAA, UAG, and UGA, which are also known as "stop codons." When these codons are encountered during translation, they cause the release of the newly synthesized polypeptide chain from the ribosome, bringing the process of protein synthesis to a halt.

Nonsense mutations are changes in the DNA sequence that result in the appearance of a nonsense codon where an amino acid-coding codon used to be. These types of mutations can lead to premature termination of translation and the production of truncated, nonfunctional proteins, which can cause genetic diseases or contribute to cancer development.

Eye abnormalities refer to any structural or functional anomalies that affect the eye or its surrounding tissues. These abnormalities can be present at birth (congenital) or acquired later in life due to various factors such as injury, disease, or aging. Some examples of eye abnormalities include:

1. Strabismus: Also known as crossed eyes, strabismus is a condition where the eyes are misaligned and point in different directions.
2. Nystagmus: This is an involuntary movement of the eyes that can be horizontal, vertical, or rotatory.
3. Cataracts: A cataract is a clouding of the lens inside the eye that can cause vision loss.
4. Glaucoma: This is a group of eye conditions that damage the optic nerve and can lead to vision loss.
5. Retinal disorders: These include conditions such as retinal detachment, macular degeneration, and diabetic retinopathy.
6. Corneal abnormalities: These include conditions such as keratoconus, corneal ulcers, and Fuchs' dystrophy.
7. Orbital abnormalities: These include conditions such as orbital tumors, thyroid eye disease, and Graves' ophthalmopathy.
8. Ptosis: This is a condition where the upper eyelid droops over the eye.
9. Color blindness: A condition where a person has difficulty distinguishing between certain colors.
10. Microphthalmia: A condition where one or both eyes are abnormally small.

These are just a few examples of eye abnormalities, and there are many others that can affect the eye and its functioning. If you suspect that you have an eye abnormality, it is important to consult with an ophthalmologist for proper diagnosis and treatment.

... it usually refers to mild variants of oculocutaneous albinism rather than ocular albinism, which is X-linked. "Ocular albinism ... Ocular albinism is a form of albinism which, in contrast to oculocutaneous albinism, presents primarily in the eyes. There are ... Sex-linked ocular albinism displaying typical fundal changes in the female heterozygote. American Journal of Ophthalmology, ... GeneReviews/NCBI/NIH/UW entry on Ocular Albinism, X-Linked (CS1 German-language sources (de), Articles with short description, ...
... (OA1) is the most common type of ocular albinism, with a prevalence rate of 1:50,000. It is an ... Ocular albinism: Evidence for a defect in an intracellular signal transduction system. Nature Genetics 23:108. "NOAH - Ocular ... Albinism may manifest itself as oculocutaneous (OCA) or just ocular (OA). There occur at least ten different types of OCA and ... Ocular albinism results from defects in the melanin system, which may arise from either defects in the OA1 receptor, or ...
It is a subtype of Ocular Albinism (OA) that is linked to Ocular albinism type I (OA1). OA1 is the most common form of ocular ... "Ocular albinism: MedlinePlus Genetics". Retrieved 2021-04-01. "Albinism, Ocular Type 1 , Hereditary Ocular ... "Albinism, Ocular Type 1 , Hereditary Ocular Diseases". Retrieved 2021-04-01. Lewis, RA (2015-11-19 ... Ocular albinism late onset sensorineural deafness (OASD) is a rare, X-linked recessive disease characterized by intense visual ...
Ocular albinism. Affects the eyes, causing blindness. Hermansky-Pudlak syndrome Effects include a bleeding disorder, IBS, and ... Albinism organisations and others have expressed criticism over the portrayal of individuals with albinism in popular culture, ... Centers, S. (2005). "Famous People with Albinism". Campbell, California: Supporting Albinism Research and ... Types of albinism include: Oculocutaneous albinism. Affects the skin, hair, and eyes. Around 1 in 70 people have a mutation in ...
"Ocular Manifestations of Albinism". eMedicine. WebMD. Archived from the original on 9 June 2007. Retrieved 31 March 2007. ... Oculocutaneous albinism is a form of albinism involving the eyes (oculo-), the skin (-cutaneous), and the hair. Overall, an ... "Orphanet: Oculocutaneous albinism". Orphanet. "OMIM Entry - #615179 - ALBINISM, OCULOCUTANEOUS, TYPE VII; OCA7". Online ... 864 Oculocutaneous albinism is also found in non-human animals. The following types of oculocutaneous albinism have been ...
An exception to this is ocular albinism, which it is passed on to offspring through X-linked inheritance. Thus, ocular albinism ... "Information Bulletin - Ocular Albinism". National Organization for Albinism and Hypopigmentation. Archived from the original on ... The other end of the spectrum of albinism is "a form of albinism called rufous oculocutaneous albinism, which usually affects ... The chance of offspring with albinism resulting from the pairing of an organism with albinism and one without albinism is low. ...
"Ocular straylight in albinism". Optom Vis Sc 2011;88:E585-E592 Van Bree MC et al. "Straylight values after refractive surgery ... Ocular straylight is a phenomenon where parts of the eye are able to scatter light, creating glare. It is analogous to stray ... Lack of pigmentation, e.g. albinism. Laser refractive surgery, with occasional haze formation. Excessive floaters in the ...
MITF Waardenburg syndrome/albinism, digenic; 103470; TYR Waardenburg syndrome/ocular albinism, digenic; 103470; MITF Wagner ... OCA2 Albinism, brown; 203290; TYRP1 Albinism, oculocutaneous, type IA; 203100; TYR Albinism, oculocutaneous, type IB; 606952; ... ATP7A Ocular albinism, type I, Nettleship-Falls type; 300500; GPR143 Oculoauricular syndrome; 612109; HMX1 Oculocutaneous ... TYR Albinism, oculocutaneous, type II; 203200; OCA2 Albinism, rufous; 278400; TYRP1 Alcohol sensitivity, acute; 610251; ALDH2 ...
He was diagnosed with ocular albinism. Skelley is married to Louise Hunt. Skelley took up judo as a sport at the age of five. A ...
... deformations in the skeleton Ocular albinism; lack of pigmentation in the eye Ornithine transcarbamylase deficiency; ... Fabry disease; A lysosomal storage disease causing anhidrosis, fatigue, angiokeratomas, burning extremity pain and ocular ...
Ocular albinism affects not only eye pigmentation but visual acuity, as well. People with albinism typically test poorly, ... Another form of Albinism, the "yellow oculocutaneous albinism", appears to be more prevalent among the Amish, who are of ... "Ocular Manifestations of Albinism: Background, Pathophysiology, Epidemiology". Medscape. Additional contributions from Kilbourn ... Similar patterns of albinism and deafness have been found in other mammals, including dogs and rodents. However, a lack of ...
Vogel P, Read RW, Vance RB, Platt KA, Troughton K, Rice DS (March 2008). "Ocular albinism and hypopigmentation defects in ... Frank Nicholas (2017-09-02). "OMIA 002124-9796: Coat colour, albinism, oculocutaneous type VI in Equus caballus". University of ... and another mutation can cause oculocutaneous albinism (OCA) type 6 (OCA6), which impairs vision. No vision impairment is seen ...
She is legally blind due to ocular albinism. In 2000, aged 28, she left her job in Accenture to launch the Aisling Foundation, ... Casey was diagnosed with ocular albinism as a child but was not personally informed until her 17th birthday. She graduated from ... People with albinism, Place of birth missing (living people), Year of birth uncertain, Alumni of University College Dublin, ...
TYRP2, for example, is important in the development of correct pigmentation; general and ocular albinism is associated with ... and the vestibulo-ocular reflex accordingly. The vestibulo-ocular reflex, one of the primary areas affected by ... Small KW, Pollock SC, Vance JM, Stajich JM, Pericak-Vance M (June 1996). "Ocular motility in North Carolina autosomal dominant ... These conditions do not consistently cause the symptoms of dizziness and ocular impairment that have been localized to the ...
Skinner has ocular albinism, a genetic condition that affects vision. He is the son of former England rugby player Mickey ... People with albinism, 1998 births, People from Tonbridge and Malling (district), British male long jumpers, Living people, ...
This protein encoded by the GPR143 gene, whose variants can lead to Ocular albinism type 1. The GPR143 gene is regulated by the ... 2006). "Scanning the ocular albinism 1 (OA1) gene for polymorphisms in congenital nystagmus by DHPLC". Ophthalmic Genet. 27 (2 ... 1996). "Analysis of the OA1 gene reveals mutations in only one-third of patients with X-linked ocular albinism". Hum. Mol. ... G-protein coupled receptor 143, also known as Ocular albinism type 1 (OA1) in humans, is a conserved integral membrane protein ...
"Ocular albinism: evidence for a defect in an intracellular signal transduction system". Nature Genetics. 23 (1): 108-12. doi: ...
He made important contributions in the research of ocular albinism, retinitis pigmentosa and hereditary night blindness. Prior ...
ISBN 978-0-511-54574-0. Aniridia at eMedicine Ocular Manifestations of Albinism at eMedicine Imesch PD, Wallow IH, Albert DM ( ... NOAH - What is Albinism? Archived 14 May 2012 at the Wayback Machine. Retrieved on 23 December 2011. Dave Johnson ... violet-colored eyes occur only due to albinism. Eyes that appear red or violet under certain conditions due to albinism are ... The ocular albino also lacks normal amounts of melanin in the retina as well, which allows more light than normal to reflect ...
She has ocular albinism and nystagmus, conditions she was born with, and is 156 centimetres (61 in) tall. Taylor has ...
... ocular albinism, optic atrophy, optic disk pallor, and optic nerve coloboma. The facial features of 1p36 deletion syndrome have ...
"Aberrant splicing in the ocular albinism type 1 gene (OA1/GPR143) is corrected in vitro by morpholino antisense ...
This gene is highly expressed in the retina, and is a strong candidate for ocular albinism type 1 syndrome. Alternatively ...
Adie's pupil, which fails to constrict in response to light; aniridia, which is absence of the iris; and albinism, where the ... Hemeralopia is known to occur in several ocular conditions. Cone dystrophy and achromatopsia, affecting the cones in the retina ... Rarely, it may have ocular complications such as hemeralopia, pigmentary chorioretinitis, optic atrophy or retinal/iris ...
The Nettleship-Falls syndrome, the most common type of ocular albinism, is named after him and English ophthalmologist Edward ...
... controls expression of the ocular albinism type 1 gene: link between melanin synthesis and melanosome biogenesis". Molecular ...
... and optic neuronal defects shared in all types of oculocutaneous and ocular albinism". The Alabama Journal of Medical Sciences ... GeneReviews/NCBI/NIH/UW entry on Oculocutaneous Albinism Type 1 Tyrosinase at the U.S. National Library of Medicine Medical ... 1087-1092, 1996 Witkop CJ (Oct 1979). "Albinism: hematologic-storage disease, susceptibility to skin cancer, ... Vitamin C Tranexamic acid While albinism is common, there have only been a few studies about the genetic mutations in the ...
Kavanagh is registered as blind, and was born with a complex visual impairment called ocular albinism, which has led to her ...
1993). "The genes for X-linked ocular albinism (OA1) and microphthalmia with linear skin defects (MLS): cloning and ... a novel gene for severe ocular malformations?". Mol. Vis. 13: 1475-82. PMID 17893649. Wapenaar MC, Bassi MT, Schaefer L, et al ... a novel gene for severe ocular malformations?". Mol. Vis. 13: 1475-82. PMID 17893649. GeneReview/NIH/UW entry on Microphthalmia ...
"The protein Ocular albinism 1 is the orphan GPCR GPR143 and mediates depressor and bradycardic responses to DOPA in the nucleus ...
... it usually refers to mild variants of oculocutaneous albinism rather than ocular albinism, which is X-linked. "Ocular albinism ... Ocular albinism is a form of albinism which, in contrast to oculocutaneous albinism, presents primarily in the eyes. There are ... Sex-linked ocular albinism displaying typical fundal changes in the female heterozygote. American Journal of Ophthalmology, ... GeneReviews/NCBI/NIH/UW entry on Ocular Albinism, X-Linked (CS1 German-language sources (de), Articles with short description, ...
Ocular albinism is a genetic condition that primarily affects the eyes. Explore symptoms, inheritance, genetics of this ... Genetic Testing Registry: Ocular albinism with late-onset sensorineural deafness *Genetic Testing Registry: Ocular albinism, ... The most common form of ocular albinism is known as the Nettleship-Falls type or type 1. Other forms of ocular albinism are ... Ocular albinism. ...
The term albinism comes from the Latin word albus, which means white, and, in 1908, Garrod first scientifically described it. ... Albinism refers to a group of hereditary disorders that involve an abnormality of melanin synthesis or distribution. ... oculocutaneous albinism and ocular albinism. Oculocutaneous albinism involves both the skin and the eyes, whereas ocular ... Ocular albinism type I is an X-linked disorder associated with the OA1 gene. Type I is the most common form of ocular albinism ...
Ocular Albinism, Hermansky-Pudlak Syndrome, Chediak-Higashi Syndrome. Published 11/01/2019 Oculocutaneous Albinism, Ocular ... Oculocutaneous Albinism, Ocular Albinism, Hermansky-Pudlak Syndrome, Chediak-Higashi Syndrome. NGS panel. Gene. Condition. ... Ocular albinism type 1 is inherited in an X-linked pattern.. Oculocutaneous albinism occurring in all populations, with an ... Oculocutaneous Albinism, Ocular Albinism, Hermansky-Pudlak Syndrome, Chediak-Higashi Syndrome *List of diseases covered by ...
The term albinism comes from the Latin word albus, which means white, and, in 1908, Garrod first scientifically described it. ... Albinism refers to a group of hereditary disorders that involve an abnormality of melanin synthesis or distribution. ... oculocutaneous albinism and ocular albinism. Oculocutaneous albinism involves both the skin and the eyes, whereas ocular ... Ocular albinism type I is an X-linked disorder associated with the OA1 gene. Type I is the most common form of ocular albinism ...
Utility of linked markers in genetic counseling: estimation of carrier risks in X-linked ocular albinism. Am J Med Genet. 1997 ... Phenotypic variability in X-linked ocular albinism: relationship to linkage genotypes. Am J Hum Genet. 1994 Sep; 55(3):484-96. ...
7. Fukai K, Holmes SA, Lucchese NJ, Siu VM, Weleber RG, Schnur RE, Spritz RA (1995). Autosomal recessive ocular albinism ...
Chris was an aspiring rugby player before his sight degraded significantly with ocular albinism. Rather than let his eyesight ...
Hermansky and Pudlak described two patients with oculocutaneous albinism (OCA) who had bleeding diathesis. Both patients had ... Abnormal foveal morphology in ocular albinism imaged with spectral-domain optical coherence tomography. Arch Ophthalmol. 2009 ... Albinism and Hermansky-Pudlak syndrome in Puerto Rico. Bol Asoc Med P R. 1990 Aug. 82(8):333-9. [QxMD MEDLINE Link]. ... Ocular findings in the Hermansky-Pudlak syndrome. Trans Am Ophthalmol Soc. 1995. 93:191-200; discussion 200-2. [QxMD MEDLINE ...
The book, The Extraordinary Life of Sam Hell: A Novel, sheds light on the lesser-known condition called ocular albinism. ...
Coloboma, Microphthalmia, Albinism, and Deafness. Clinical Characteristics. Ocular Features: A 5 year old male has been ... Ocular histopathologic studies of neonatal and childhood adrenoleukodystrophy. Cohen SM, Green WR, de la Cruz ZC, Brown FR 3rd ... Ocular Features: The eyes are deep-set and the palpebral fissures slant downward. Optic atrophy is often present. The majority ... Ocular Features: Progressive optic atrophy is considered part of this syndrome but it is not a consistent feature. One patient ...
"Some kids were born with a retinal hereditary disorder that causes vision impairment, such as (ocular) albinism (a group of ...
Ocular albinism affects the eyes and usually not the skin... read more because of a defect in melanin metabolism. Patchy areas ... There is no skin pigmentation in people with albinism Albinism Oculocutaneous albinism is an inherited defect in melanin ...
76 13 83 Albinism (ocular) 76 14 00 Dialysis, retina, congenital 76 14 00 Disinsertion, retina, congenital 76 15 00 Color ... secondary to other ocular disease (punctate). /Code also the other ocular disease/ 67 75 01 Keratitis sicca, congenital ( ... If CVA is reported in Section A, assume ocular impairment unless examiner specifically states there was none/ 99 00 81 Disease ... ITEM DESCRIPTION & CODES Counts HANES I Data Source 225 SIGNIFICANT OCULAR HISTORY 1 - Yes 1291 2 - No 8592 Blank 244 226- ...
Ocular findings include reduced iris pigment with iris transillumination, reduced retinal pigment, foveal hypoplasia with ... is characterized by oculocutaneous albinism, a bleeding diathesis, and, in some individuals, pulmonary fibrosis, granulomatous ... Novel HPS6 mutations identified by whole-exome sequencing in two Japanese sisters with suspected ocular albinism. ... Ocular findings include nystagmus, reduced iris pigment, reduced retinal pigment, foveal hypoplasia with significant reduction ...
Nystagmus, congenital, Ocular albinism. XL. 22. 181. HESX1 Septooptic dysplasia, Pituitary hormone deficiency, combined, ... Acro-renal-ocular syndrome, Duane-radial ray/Okihiro syndrome. AD. 21. 56. ... Aniridia, cerebellar ataxia, and mental retardation (Gillespie syndrome), Keratitis, Coloboma, ocular, Cataract with late-onset ... spontaneous and involuntary ocular oscillations that appear at birth or during the first three months of life. Binocular vision ...
Partial ocular albinism; Symptoms Subdural hematoma; Speech developmental delay; Symptoms Impaired chemotaxis; Age 3.5 Sex XY ... Occulocutaneous albinism; Age 8 mo Sex XY Ethnic origin Caucasoid Parents Non-consanguineous // ID F1334V(1),F1334V(1); ...
GNAI3: Another Candidate Gene to Screen in Persons with Ocular Albinism. Young Alejandra, et al. PloS one 2016 0 (9) e0162273 ... Ocular albinism type 1 From NCATS Genetic and Rare Diseases Information Center ...
Trauma Occupational Diseases Ochoa Syndrome Ocular Larva Migrans Ocular Motility Disorders Ocular Retraction Syndrome Ocular ... Laparoscopic Surgical Procedures Laparoscopy Larsen Syndrome Larva Migrans Larva Migrans Cutaneous Larva Migrans Ocular ...
In addition, one patient had the comorbidity of oculocutaneous albinism (OCA). Eight different PAX2 variants were found in ten ... Three children had PAX2-related ocular abnormalities, including nystagmus, retinal exudation, amblyopia, microphthalmia, ...
Hermansky and Pudlak described two patients with oculocutaneous albinism (OCA) who had bleeding diathesis. Both patients had ... Abnormal foveal morphology in ocular albinism imaged with spectral-domain optical coherence tomography. Arch Ophthalmol. 2009 ... Albinism and Hermansky-Pudlak syndrome in Puerto Rico. Bol Asoc Med P R. 1990 Aug. 82(8):333-9. [QxMD MEDLINE Link]. ... Ocular findings in the Hermansky-Pudlak syndrome. Trans Am Ophthalmol Soc. 1995. 93:191-200; discussion 200-2. [QxMD MEDLINE ...
Ocular Albinism is a genetic condition /Mutation ,with the lack of pigmentation at the back of the eyes . Melanin is provided ...
Unlike some other forms of albinism, ocular albinism does not significantly affect the color of the skin and hair. Spotters ...
Generally this is associated with albinism and ocular albinism, hereditary conditions that do not run in either of our families ...
Oculocutaneous Albinism. OCA which is characterized by diminished melanin pigmentation in the skin and eyes, as well as vision ... Nitisinone has minimal adverse events with ocular symptoms like irritation, corneal erosions, and photophobia if not on ... Nitisinone has minimal adverse events with ocular symptoms like irritation, corneal erosions, photophobia if not on tyrosine ... Dermatological uses of nitisinone are oculocutaneous albinism, hereditary tyrosinemia, African trypanosomiasis, and ...
... an effect of a condition called ocular albinism. He has a tough life, but its made bearable when he makes two friends: Eddie ...
Low vision can be due to heredity, an ocular injury, or aging. Some of the most common causes of low vision are macular ... degeneration, glaucoma, diabetic retinopathy, optic atrophy, retinitis pigmentosa, retinal detachment, albinism and stroke. ... These tests may include visual field testing, fundus photography, and/or ocular coherence tomography. ...
... and Asia.These findings will help to improve the understanding of eye diseases such as pigmentary glaucoma and ocular albinism ...
  • Ocular albinism is a form of albinism which, in contrast to oculocutaneous albinism, presents primarily in the eyes. (
  • When the term "autosomal recessive ocular albinism" ("AROA") is used, it usually refers to mild variants of oculocutaneous albinism rather than ocular albinism, which is X-linked. (
  • Albinism can be divided into 2 broad categories, as follows: oculocutaneous albinism and ocular albinism. (
  • Oculocutaneous albinism involves both the skin and the eyes, whereas ocular albinism mainly affects the eyes with minimal to no skin involvement. (
  • The primary morbidity of both oculocutaneous albinism and ocular albinism is eye related. (
  • Oculocutaneous albinism is mostly an autosomal recessive disorder, whereas ocular albinism is transmitted as a sex-linked or autosomal recessive disease. (
  • Oculocutaneous albinism is divided into approximately 10 different types. (
  • [ 2 ] and type II (tyrosinase positive) oculocutaneous albinism. (
  • Another important form of oculocutaneous albinism is type IB, which was previously called yellow mutant oculocutaneous albinism. (
  • Two additional rare types of oculocutaneous albinism with important systemic findings and an increased risk of mortality are Hermansky-Pudlak syndrome and Chediak-Higashi syndrome . (
  • The pathophysiology of oculocutaneous albinism involves a reduction in the amount of melanin present in each of the melanosomes. (
  • This results in type I oculocutaneous albinism, which is characterized by complete absence of skin and eye pigmentation, despite a normal number of melanosomes. (
  • In contrast, the type II (tyrosine positive) oculocutaneous albinism defect is within the P polypeptide, which is a melanosomal tyrosine transporter. (
  • Oculocutaneous albinism (OCA) is a group of rare inherited disorders characterized by a reduction or complete lack of melanin pigment in the skin, hair and eyes. (
  • Chediak-Higashi syndrome (CHS) is an inherited, complex, immune disorder that usually occurs in childhood (at birth or shortly thereafter) characterized by oculocutaneous albinism, nervous system abnormalities, immune deficiency with an increased susceptibility to infections, and a tendency to easy bruising and abnormal bleeding. (
  • In 1959, Hermansky and Pudlak described two patients with oculocutaneous albinism (OCA) who had bleeding diathesis. (
  • Hermansky-Pudlak syndrome (HPS) is a heterogeneous group of autosomal recessive disorders characterized by tyrosinase-positive oculocutaneous albinism (Ty-pos OCA), bleeding tendencies, and systemic complications associated to lysosomal dysfunction. (
  • Hermansky-Pudlak syndrome-6 (HPS6) is characterized by a presentation of oculocutaneous albinism and bleeding diathesis. (
  • Dermatological uses of nitisinone are oculocutaneous albinism, hereditary tyrosinemia, African trypanosomiasis, and alkaptonuria and the nondermatological indication is ocular neuroblastoma. (
  • Most forms of albinism are inherited in an autosomal recessive fashion, which means that it is passed directly from unaffected parents to their children ( Figure 1 ). (
  • Patients with type I disease have no skin or ocular pigmentation, whereas those with type II disease can develop some pigmentation as they grow older. (
  • Patients with type IB are similar to those with type I but can exhibit some pigmentation of their skin, hair, and ocular structures. (
  • Albinism is typically diagnosed based on the observation that the skin, hair, and eyes have decreased or absent pigmentation compared to members of the same family or ethnic group. (
  • ocular albinism is a pigmentation deficiency occurring mainly in the eyes. (
  • One form, ocular albinism, affects only the eyes leaving the skin and hair pigmentation nearly normal. (
  • Ocular findings include nystagmus, reduced iris pigment, reduced retinal pigment, foveal hypoplasia with significant reduction in visual acuity (usually in the range of 20/50 to 20/400), and strabismus in many individuals. (
  • Congenital nystagmus is defined as conjugated, spontaneous and involuntary ocular oscillations that appear at birth or during the first three months of life. (
  • The symptoms of albinism begin early in childhood and may include decreased vision, sensitivity to bright lights, and unintentional jiggling movement of the eye (nystagmus) and misalignment of the eyes (strabismus). (
  • The most common form of ocular albinism is known as the Nettleship-Falls type or type 1. (
  • Rare cases of ocular albinism are not caused by mutations in the GPR143 gene. (
  • Ocular albinism is a genetic condition that primarily affects the eyes. (
  • Albinism is a genetic condition that decreases the production of melanin , resulting in a fair skin complexion, light eyes and hair, and increased susceptibility to various skin and eye conditions. (
  • Ocular albinism type 1 results from mutations in the GPR143 gene. (
  • In males (who have only one X chromosome), one altered copy of the GPR143 gene in each cell is sufficient to cause the characteristic features of ocular albinism. (
  • Albinism refers to a group of hereditary disorders that involve an abnormality of melanin synthesis or distribution. (
  • Albinism is caused by a disorder of melanin metabolism, and the defect can lie with either melanin synthesis or distribution. (
  • Albinism is a disorder of the synthesis of the pigment melanin. (
  • Some kids were born with a retinal hereditary disorder that causes vision impairment, such as (ocular) albinism (a group of inherited disorders that lead to little or no production of melanin and can affect eye function). (
  • Albinism is a genetic disorder that results in decreased production of a pigment called melanin in the skin, hair, and eyes, resulting in light color or no color. (
  • The inheritance pattern of albinism is also quite variable. (
  • There are multiple forms of ocular albinism, which are clinically similar. (
  • Researchers are uncertain how these giant melanosomes are related to vision loss and other eye abnormalities in people with ocular albinism. (
  • Currently there is no cure for albinism, however it can be managed using sunscreen, protective clothing, eyeglasses, magnifying glasses, or eye surgery for eye abnormalities. (
  • Hermansky-Pudlak syndrome (HPS) is a multisystem, hereditary disorder characterized mainly by albinism with visual impairment and blood platelet dysfunction with prolonged bleeding. (
  • Genes can be tested to determine the specific type of albinism the patient has. (
  • The most common form of this disorder, ocular albinism type 1, affects at least 1 in 60,000 males. (
  • Ocular albinism type I is an X-linked disorder associated with the OA1 gene. (
  • Ocular albinism type I is an X-linked disorder related to defects in the OA1 gene. (
  • Albinism is often suspected from a person's general appearance or through a family history of the disorder. (
  • Ocular albinism (OA) primarily affects the eyes, and does not significantly affect the color of the skin and hair. (
  • In two rare forms of albinism affected individuals can have bleeding problems, increase susceptibility to infections especially during childhood. (
  • Female carriers can show minor signs, whereas males with ocular albinism can show a constellation of any of the above-mentioned findings. (
  • Continuous variables in the groups were com- correlated with the ocular findings of the subject, a pattern pared using the independent-samples t -test and the cat- visual evoked potential test was ordered. (
  • Most people with Oscillopsia have abnormal eye movements as a result of which there is excessive motion of images in the retina or there is an abnormality with the vestibulo-ocular reflex. (
  • Nitisinone has minimal adverse events with ocular symptoms like irritation, corneal erosions, and photophobia if not on tyrosine restricted diet in HT. (
  • Other forms of ocular albinism are much rarer and may be associated with additional signs and symptoms, such as hearing loss. (
  • What are the symptoms of albinism? (
  • The P gene has been mapped to chromosome 15 and is more commonly linked with albinism in patients of African descent. (
  • Unlike some other forms of albinism, ocular albinism does not significantly affect the color of the skin and hair. (
  • Chris was an aspiring rugby player before his sight degraded significantly with ocular albinism. (
  • Ocular albinism is characterized by severely impaired sharpness of vision (visual acuity) and problems with combining vision from both eyes to perceive depth (stereoscopic vision). (
  • People with ocular albinism have a lack of pigment in their eyes, which can give them a translucent or "demonic" appearance. (
  • Albinism is an inherited condition in which the eyes, hair and/or skin have less than normal amounts of pigment. (
  • Some children and adults with albinism can have a total lack of pigment with white skin and hair and pink-colored eyes. (
  • Albinism results from the inability of the normal pigment cells in the eyes, hair or skin to produce normal amounts of pigment. (
  • Type I is the most common form of ocular albinism. (
  • The most common form of OA is type 1 (OA1), also named X-linked ocular albinism. (
  • It is the third most prevalent form of albinism. (
  • it affects 1 in 20,000 Americans and is more common in other parts of the world, such as in Zimbabwe, Africa, where 1 in 1,000 people have some form of albinism. (
  • Ocular albinism type 1 is inherited in an X-linked pattern. (
  • Cortese K, Giordano F, Surace EM, Venturi C, Ballabio A, Tacchetti C, Marigo V. The ocular albinism type 1 (OA1) gene controls melanosome maturation and size. (
  • however, the degree of their presentation can vary depending on the type of albinism and the racial background of the patient. (
  • A complete medical eye exam by an ophthalmologist, a general physical examination, and a genetic evaluation can help diagnose and define the type of albinism. (
  • In the ocular examination of the retinography, intense subhyaloidal hemorrhage. (
  • to legal blindness or worse for those with more sever forms of albinism. (
  • Generally this is associated with albinism and ocular albinism, hereditary conditions that do not run in either of our families. (
  • In severe cases of albinism the eye's central vision area, the macula does not develop properly resulting in poor vision. (
  • Some individuals with albinism may be entitled to help from visual assistance programs. (
  • individuals with albinism including ocular al. (
  • The National Organization for Albinism and Hypopigmentation (NOAH) is a nonprofit organization formed for benefit of families and individuals with these conditions. (
  • The term albinism comes from the Latin word albus, which means white, and, in 1908, Garrod first scientifically described it. (