Retinitis Pigmentosa
Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.
Cytomegalovirus Retinitis
Infection of the retina by cytomegalovirus characterized by retinal necrosis, hemorrhage, vessel sheathing, and retinal edema. Cytomegalovirus retinitis is a major opportunistic infection in AIDS patients and can cause blindness.
Eye Proteins
'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.
Rhodopsin
A purplish-red, light-sensitive pigment found in RETINAL ROD CELLS of most vertebrates. It is a complex consisting of a molecule of ROD OPSIN and a molecule of 11-cis retinal (RETINALDEHYDE). Rhodopsin exhibits peak absorption wavelength at about 500 nm.
Retinitis
Retinal Degeneration
A retrogressive pathological change in the retina, focal or generalized, caused by genetic defects, inflammation, trauma, vascular disease, or aging. Degeneration affecting predominantly the macula lutea of the retina is MACULAR DEGENERATION. (Newell, Ophthalmology: Principles and Concepts, 7th ed, p304)
Photoreceptor Cells, Vertebrate
Genes, Dominant
Genes that influence the PHENOTYPE both in the homozygous and the heterozygous state.
Pedigree
Genes, Recessive
Genes that influence the PHENOTYPE only in the homozygous state.
Retina
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.
Peripherins
Type III intermediate filament proteins expressed mainly in neurons of the peripheral and CENTRAL NERVOUS SYSTEMS. Peripherins are implicated in neurite elongation during development and axonal regeneration after injury.
Genetic Diseases, X-Linked
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.
Dark Adaptation
Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
Fundus Oculi
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)
Visual Acuity
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.
Photoreceptor Cells
Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.
Cyclic Nucleotide Phosphodiesterases, Type 6
A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC GMP. It is found predominantly in the outer segment PHOTORECEPTOR CELLS of the RETINA. It is comprised of two catalytic subunits, referred to as alpha and beta, that form a dimer. In addition two regulatory subunits, referred to as gamma and delta, modulate the activity and localization of the enzyme.
Retinal Rod Photoreceptor Cells
Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination.
Visual Fields
Usher Syndromes
Autosomal recessive hereditary disorders characterized by congenital SENSORINEURAL HEARING LOSS and RETINITIS PIGMENTOSA. Genetically and symptomatically heterogeneous, clinical classes include type I, type II, and type III. Their severity, age of onset of retinitis pigmentosa and the degree of vestibular dysfunction are variable.
Retinal Cone Photoreceptor Cells
Photosensitive afferent neurons located primarily within the FOVEA CENTRALIS of the MACULA LUTEA. There are three major types of cone cells (red, blue, and green) whose photopigments have different spectral sensitivity curves. Retinal cone cells operate in daylight vision (at photopic intensities) providing color recognition and central visual acuity.
Mutation
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.
Night Blindness
Failure or imperfection of vision at night or in dim light, with good vision only on bright days. (Dorland, 27th ed)
Genetic Linkage
Rod Opsins
Photosensitive proteins expressed in the ROD PHOTORECEPTOR CELLS. They are the protein components of rod photoreceptor pigments such as RHODOPSIN.
Blindness
Visual Field Tests
X Chromosome
Exons
Mutation, Missense
A mutation in which a codon is mutated to one directing the incorporation of a different amino acid. This substitution may result in an inactive or unstable product. (From A Dictionary of Genetics, King & Stansfield, 5th ed)
Eye Diseases, Hereditary
Fluorescein Angiography
Tomography, Optical Coherence
IMP Dehydrogenase
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Laurence-Moon Syndrome
An autosomal recessive condition characterized by hypogonadism; spinocerebellar degeneration; MENTAL RETARDATION; RETINITIS PIGMENTOSA; and OBESITY. This syndrome was previously referred to as Laurence-Moon-Biedl syndrome until BARDET-BIEDL SYNDROME was identified as a distinct entity. (From N Engl J Med. 1989 Oct 12;321(15):1002-9)
Retinal Diseases
Leber Congenital Amaurosis
A rare degenerative inherited eye disease that appears at birth or in the first few months of life that results in a loss of vision. Not to be confused with LEBER HEREDITARY OPTIC NEUROPATHY, the disease is thought to be caused by abnormal development of PHOTORECEPTOR CELLS in the RETINA, or by the extremely premature degeneration of retinal cells.
Ribonucleoprotein, U4-U6 Small Nuclear
A nuclear RNA-protein complex that plays a role in RNA processing. In the nucleoplasm, the U4-U6 snRNP along with the U5 snRNP preassemble into a single 25S particle that binds to the U1 and U2 snRNPs and the substrate to form mature SPLICEOSOMES. There is also evidence for the existence of individual U4 or U6 snRNPs in addition to their organization as a U4-U6 snRNP.
Retinal Photoreceptor Cell Outer Segment
The light sensitive outer portion of a retinal rod or a cone photoreceptor cell. The outer segment contains a stack of disk membranes laden with photoreceptive pigments (RETINAL PIGMENTS). The outer segment is connected to the inner segment by a PHOTORECEPTOR CONNECTING CILIUM.
Tetraspanins
A large superfamily of cell surface membrane proteins characterized by their four transmembrane domains. They play a role in a variety of processes such as cellular adhesion and motility. They may be involved in the organization of cell surface MEMBRANE MICRODOMAINS that regulate the activation of LEUKOCYTES.
Fovea Centralis
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)
Lod Score
Vision Disorders
Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).
Intermediate Filament Proteins
Polymorphism, Single-Stranded Conformational
Variation in a population's DNA sequence that is detected by determining alterations in the conformation of denatured DNA fragments. Denatured DNA fragments are allowed to renature under conditions that prevent the formation of double-stranded DNA and allow secondary structure to form in single stranded fragments. These fragments are then run through polyacrylamide gels to detect variations in the secondary structure that is manifested as an alteration in migration through the gels.
Photoreceptor Connecting Cilium
Phenotype
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
Chromosome Mapping
Opsins
Photosensitive proteins in the membranes of PHOTORECEPTOR CELLS such as the rods and the cones. Opsins have varied light absorption properties and are members of the G-PROTEIN-COUPLED RECEPTORS family. Their ligands are VITAMIN A-based chromophores.
Frameshift Mutation
A type of mutation in which a number of NUCLEOTIDES deleted from or inserted into a protein coding sequence is not divisible by three, thereby causing an alteration in the READING FRAMES of the entire coding sequence downstream of the mutation. These mutations may be induced by certain types of MUTAGENS or may occur spontaneously.
Genes, X-Linked
Genes that are located on the X CHROMOSOME.
Retinal Dysplasia
Macula Lutea
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)
Disease Models, Animal
Optic Atrophy, Hereditary, Leber
A maternally linked genetic disorder that presents in mid-life as acute or subacute central vision loss leading to central scotoma and blindness. The disease has been associated with missense mutations in the mtDNA, in genes for Complex I, III, and IV polypeptides, that can act autonomously or in association with each other to cause the disease. (from Online Mendelian Inheritance in Man, http://www.ncbi.nlm.nih.gov/Omim/, MIM#535000 (April 17, 2001))
Ataxia
Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or PERIPHERAL NERVE DISEASES. Motor ataxia may be associated with CEREBELLAR DISEASES; CEREBRAL CORTEX diseases; THALAMIC DISEASES; BASAL GANGLIA DISEASES; injury to the RED NUCLEUS; and other conditions.
Phosphenes
A subjective visual sensation with the eyes closed and in the absence of light. Phosphenes can be spontaneous, or induced by chemical, electrical, or mechanical (pressure) stimuli which cause the visual field to light up without optical inputs.
Amino Acid Sequence
Heterozygote
Base Sequence
Eye Infections, Viral
Infections of the eye caused by minute intracellular agents. These infections may lead to severe inflammation in various parts of the eye - conjunctiva, iris, eyelids, etc. Several viruses have been identified as the causative agents. Among these are Herpesvirus, Adenovirus, Poxvirus, and Myxovirus.
Codon, Nonsense
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.
Vision, Ocular
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
Bardet-Biedl Syndrome
An autosomal recessive disorder characterized by RETINITIS PIGMENTOSA; POLYDACTYLY; OBESITY; MENTAL RETARDATION; hypogenitalism; renal dysplasia; and short stature. This syndrome has been distinguished as a separate entity from LAURENCE-MOON SYNDROME. (From J Med Genet 1997 Feb;34(2):92-8)
Retinal Dystrophies
A group of disorders involving predominantly the posterior portion of the ocular fundus, due to degeneration in the sensory layer of the RETINA; RETINAL PIGMENT EPITHELIUM; BRUCH MEMBRANE; CHOROID; or a combination of these tissues.
Sequence Analysis, DNA
Cilia
Populations of thin, motile processes found covering the surface of ciliates (CILIOPHORA) or the free surface of the cells making up ciliated EPITHELIUM. Each cilium arises from a basic granule in the superficial layer of CYTOPLASM. The movement of cilia propels ciliates through the liquid in which they live. The movement of cilia on a ciliated epithelium serves to propel a surface layer of mucus or fluid. (King & Stansfield, A Dictionary of Genetics, 4th ed)
Polymerase Chain Reaction
In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.
Vision, Low
Vision considered to be inferior to normal vision as represented by accepted standards of acuity, field of vision, or motility. Low vision generally refers to visual disorders that are caused by diseases that cannot be corrected by refraction (e.g., MACULAR DEGENERATION; RETINITIS PIGMENTOSA; DIABETIC RETINOPATHY, etc.).
Point Mutation
A mutation caused by the substitution of one nucleotide for another. This results in the DNA molecule having a change in a single base pair.
Rats, Transgenic
Visual Prosthesis
Artificial device such as an externally-worn camera attached to a stimulator on the RETINA, OPTIC NERVE, or VISUAL CORTEX, intended to restore or amplify vision.
Rod Cell Outer Segment
The portion of a retinal rod cell situated between the ROD INNER SEGMENT and the RETINAL PIGMENT EPITHELIUM. It contains a stack of photosensitive disk membranes laden with RHODOPSIN.
Ophthalmoscopes
Genotype
Electrooculography
Recording of the average amplitude of the resting potential arising between the cornea and the retina in light and dark adaptation as the eyes turn a standard distance to the right and the left. The increase in potential with light adaptation is used to evaluate the condition of the retinal pigment epithelium.
Optic Atrophies, Hereditary
Hereditary conditions that feature progressive visual loss in association with optic atrophy. Relatively common forms include autosomal dominant optic atrophy (OPTIC ATROPHY, AUTOSOMAL DOMINANT) and Leber hereditary optic atrophy (OPTIC ATROPHY, HEREDITARY, LEBER).
Foscarnet
An antiviral agent used in the treatment of cytomegalovirus retinitis. Foscarnet also shows activity against human herpesviruses and HIV.
Carrier Proteins
RNA Splicing
Retinal Bipolar Cells
INTERNEURONS of the vertebrate RETINA containing two processes. They receive inputs from the RETINAL PHOTORECEPTOR CELLS and send outputs to the RETINAL GANGLION CELLS. The bipolar cells also make lateral connections in the retina with the RETINAL HORIZONTAL CELLS and with the AMACRINE CELLS.
Retinal Pigment Epithelium
The single layer of pigment-containing epithelial cells in the RETINA, situated closely to the tips (outer segments) of the RETINAL PHOTORECEPTOR CELLS. These epithelial cells are macroglia that perform essential functions for the photoreceptor cells, such as in nutrient transport, phagocytosis of the shed photoreceptor membranes, and ensuring retinal attachment.
Arrestin
Chromosomes, Human, Pair 19
Pigment Epithelium of Eye
The layer of pigment-containing epithelial cells in the RETINA; the CILIARY BODY; and the IRIS in the eye.
Genetic Heterogeneity
The presence of apparently similar characters for which the genetic evidence indicates that different genes or different genetic mechanisms are involved in different pedigrees. In clinical settings genetic heterogeneity refers to the presence of a variety of genetic defects which cause the same disease, often due to mutations at different loci on the same gene, a finding common to many human diseases including ALZHEIMER DISEASE; CYSTIC FIBROSIS; LIPOPROTEIN LIPASE DEFICIENCY, FAMILIAL; and POLYCYSTIC KIDNEY DISEASES. (Rieger, et al., Glossary of Genetics: Classical and Molecular, 5th ed; Segen, Dictionary of Modern Medicine, 1992)
Dependovirus
Retinal Photoreceptor Cell Inner Segment
The inner portion of a retinal rod or a cone photoreceptor cell, situated between the PHOTORECEPTOR CONNECTING CILIUM and the synapse with the adjacent neurons (RETINAL BIPOLAR CELLS; RETINAL HORIZONTAL CELLS). The inner segment contains the cell body, the nucleus, the mitochondria, and apparatus for protein synthesis.
Optic Disk Drusen
Optic disk bodies composed primarily of acid mucopolysaccharides that may produce pseudopapilledema (elevation of the optic disk without associated INTRACRANIAL HYPERTENSION) and visual field deficits. Drusen may also occur in the retina (see RETINAL DRUSEN). (Miller et al., Clinical Neuro-Ophthalmology, 4th ed, p355)