Lenses. Medical search

Pieces of glass or other transparent materials used for magnification or increased visual acuity.

Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)

Soft, supple contact lenses made of plastic polymers which interact readily with water molecules. Many types are available, including continuous and extended-wear versions, which are gas-permeable and easily sterilized.

Artificial implanted lenses.

The portion of the crystalline lens surrounding the nucleus and bound anteriorly by the epithelium and posteriorly by the capsule. It contains lens fibers and amorphous, intercellular substance.

The thin noncellular outer covering of the CRYSTALLINE LENS composed mainly of COLLAGEN TYPE IV and GLYCOSAMINOGLYCANS. It is secreted by the embryonic anterior and posterior epithelium. The embryonic posterior epithelium later disappears.

The core of the crystalline lens, surrounded by the cortex.

Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)

A heterogeneous family of water-soluble structural proteins found in cells of the vertebrate lens. The presence of these proteins accounts for the transparency of the lens. The family is composed of four major groups, alpha, beta, gamma, and delta, and several minor groups, which are classed on the basis of size, charge, immunological properties, and vertebrate source. Alpha, beta, and delta crystallins occur in avian and reptilian lenses, while alpha, beta, and gamma crystallins occur in all other lenses.

Hydrophilic contact lenses worn for an extended period or permanently.

Incomplete rupture of the zonule with the displaced lens remaining behind the pupil. In dislocation, or complete rupture, the lens is displaced forward into the anterior chamber or backward into the vitreous body. When congenital, this condition is known as ECTOPIA LENTIS.

Sterile solutions used to clean and disinfect contact lenses.

Insertion of an artificial lens to replace the natural CRYSTALLINE LENS after CATARACT EXTRACTION or to supplement the natural lens which is left in place.

The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.

The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)

Refraction of LIGHT effected by the media of the EYE.

The posterior aspect of the casing that surrounds the natural CRYSTALLINE LENS.

A class of crystallins that provides refractive power and translucency to the lens (LENS, CRYSTALLINE) in VERTEBRATES. Beta-crystallins are similar in structure to GAMMA-CRYSTALLINS in that they both contain Greek key motifs. Beta-crystallins exist as oligomers formed from acidic (BETA-CRYSTALLIN A CHAIN) and basic (BETA-CRYSTALLIN B CHAIN) subunits.

The removal of a cataractous CRYSTALLINE LENS from the eye.

Absence of crystalline lens totally or partially from field of vision, from any cause except after cataract extraction. Aphakia is mainly congenital or as result of LENS DISLOCATION AND SUBLUXATION.

A pair of ophthalmic lenses in a frame or mounting which is supported by the nose and ears. The purpose is to aid or improve vision. It does not include goggles or nonprescription sun glasses for which EYE PROTECTIVE DEVICES is available.

A subclass of crystallins that provides the majority of refractive power and translucency to the lens (LENS, CRYSTALLINE) in VERTEBRATES. Alpha-crystallins also act as molecular chaperones that bind to denatured proteins, keep them in solution and thereby maintain the translucency of the lens. The proteins exist as large oligomers that are formed from ALPHA-CRYSTALLIN A CHAIN and ALPHA-CRYSTALLIN B CHAIN subunits.

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 plant genus of the FABACEAE family known for the seeds used as food.

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)

The anterior aspect of the casing that surrounds the natural CRYSTALLINE LENS.

A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.

A broad family of synthetic organosiloxane polymers containing a repeating silicon-oxygen backbone with organic side groups attached via carbon-silicon bonds. Depending on their structure, they are classified as liquids, gels, and elastomers. (From Merck Index, 12th ed)

A procedure for removal of the crystalline lens in cataract surgery in which an anterior capsulectomy is performed by means of a needle inserted through a small incision at the temporal limbus, allowing the lens contents to fall through the dilated pupil into the anterior chamber where they are broken up by the use of ultrasound and aspirated out of the eye through the incision. (Cline, et al., Dictionary of Visual Science, 4th ed & In Focus 1993;1(1):1)

A subclass of crystallins found in the lens (LENS, CRYSTALLINE) in BIRDS and REPTILES. They are inactive forms of the enzyme argininosuccinate lyase.

Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.

A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus behind the retina, as a result of the eyeball being too short from front to back. It is also called farsightedness because the near point is more distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed)

Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.

A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.

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.

Lenses, generally made of plastic or silicone, that are implanted into the eye in front of the natural EYE LENS, by the IRIS, to improve VISION, OCULAR. These intraocular lenses are used to supplement the natural lens instead of replacing it.

Presence of an intraocular lens after cataract extraction.

A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES.

The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.

Absence of the crystalline lens resulting from cataract extraction.

The basic subunit of beta-crystallins.

Polymers of silicone that are formed by crosslinking and treatment with amorphous silica to increase strength. They have properties similar to vulcanized natural rubber, in that they stretch under tension, retract rapidly, and fully recover to their original dimensions upon release. They are used in the encapsulation of surgical membranes and implants.

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.

The making of a continuous circular tear in the anterior capsule during cataract surgery in order to allow expression or phacoemulsification of the nucleus of the lens. (Dorland, 28th ed)

Inflammation of the cornea.

The fitting and adjusting of artificial parts of the body. (From Stedman's, 26th ed)

An excessive amount of fluid in the cornea due to damage of the epithelium or endothelium causing decreased visual acuity.

One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.

Maf proto-oncogene protein is the major cellular homolog of the V-MAF ONCOGENE PROTEIN. It was the first of the mammalian MAF TRANSCRIPTION FACTORS identified, and it is induced in activated T-LYMPHOCYTES and regulates GENETIC TRANSCRIPTION of INTERLEUKIN-4. c-maf is frequently translocated to an immunoglobulin locus in MULTIPLE MYELOMA.

A family of transcription factors that control EMBRYONIC DEVELOPMENT within a variety of cell lineages. They are characterized by a highly conserved paired DNA-binding domain that was first identified in DROSOPHILA segmentation genes.

The front third of the eyeball that includes the structures between the front surface of the cornea and the front of the VITREOUS BODY.

The fluid secreted by the lacrimal glands. This fluid moistens the CONJUNCTIVA and CORNEA.

The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.

Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)

Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

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.

One of the alpha crystallin subunits. In addition to being expressed in the lens (LENS, CRYSTALLINE), alpha-crystallin B chain has been found in a variety of tissues such as HEART; BRAIN; MUSCLE; and KIDNEY. Accumulation of the protein in the brain is associated with NEURODEGENERATIVE DISEASES such as CREUTZFELDT-JAKOB SYNDROME and ALEXANDER DISEASE.

Congenital or developmental anomaly in which the eyeballs are abnormally small.

A family of Urodela consisting of 15 living genera and about 42 species and occurring in North America, Europe, Asia, and North Africa.

A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions.

A ring of tissue extending from the scleral spur to the ora serrata of the RETINA. It consists of the uveal portion and the epithelial portion. The ciliary muscle is in the uveal portion and the ciliary processes are in the epithelial portion.

The acidic subunit of beta-crystallins.

The use of statistical and mathematical methods to analyze biological observations and phenomena.

Infection of the cornea by an ameboid protozoan which may cause corneal ulceration leading to blindness.

Loss of epithelial tissue from the surface of the cornea due to progressive erosion and necrosis of the tissue; usually caused by bacterial, fungal, or viral infection.

Diseases of the cornea.

The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.

A form of fluorescent antibody technique commonly used to detect serum antibodies and immune complexes in tissues and microorganisms in specimens from patients with infectious diseases. The technique involves formation of an antigen-antibody complex which is labeled with fluorescein-conjugated anti-immunoglobulin antibody. (From Bennington, Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)

An enzyme that catalyzes reversibly the oxidation of an aldose to an alditol. It possesses broad specificity for many aldoses. EC 1.1.1.21.

The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.

A technique for maintenance or growth of animal organs in vitro. It refers to three-dimensional cultures of undisaggregated tissue retaining some or all of the histological features of the tissue in vivo. (Freshney, Culture of Animal Cells, 3d ed, p1)

A network of cross-linked hydrophilic macromolecules used in biomedical applications.

Method of making images on a sensitized surface by exposure to light or other radiant energy.

Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.

A species of newt in the Salamandridae family in which the larvae transform into terrestrial eft stage and later into an aquatic adult. They occur from Canada to southern United States. Viridescens refers to the greenish color often found in this species.

Clouding or loss of transparency of the posterior lens capsule, usually following CATARACT extraction.

A genus of free-living soil amoebae that produces no flagellate stage. Its organisms are pathogens for several infections in humans and have been found in the eye, bone, brain, and respiratory tract.

The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Diseases affecting the eye.

A noninflammatory, usually bilateral protrusion of the cornea, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. The cause is unknown but hereditary factors may play a role. The -conus refers to the cone shape of the corneal protrusion. (From Dorland, 27th ed)

Apparatus, devices, or supplies intended for one-time or temporary use.

Congenital absence of or defects in structures of the eye; may also be hereditary.

Polymerized methyl methacrylate monomers which are used as sheets, moulding, extrusion powders, surface coating resins, emulsion polymers, fibers, inks, and films (From International Labor Organization, 1983). This material is also used in tooth implants, bone cements, and hard corneal contact lenses.

A scientific tool based on ULTRASONOGRAPHY and used not only for the observation of microstructure in metalwork but also in living tissue. In biomedical application, the acoustic propagation speed in normal and abnormal tissues can be quantified to distinguish their tissue elasticity and other properties.

Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.

An alternative to REFRACTIVE SURGICAL PROCEDURES. A therapeutic procedure for correcting REFRACTIVE ERRORS. It involves wearing CONTACT LENSES designed to force corrective changes to the curvature of the CORNEA that remain after the lenses are removed. The effect is temporary but is maintained by wearing the therapeutic lenses daily, usually during sleep.

Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.

Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.

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.

A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.

Centers for storing various parts of the eye for future use.

Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.

The methyl esters of methacrylic acid that polymerize easily and are used as tissue cements, dental materials, and absorbent for biological substances.

That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.

Damage or trauma inflicted to the eye by external means. The concept includes both surface injuries and intraocular injuries.

A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.

The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. It receives the tendons of insertion of the extraocular muscles and at the corneoscleral junction contains the canal of Schlemm. (From Cline et al., Dictionary of Visual Science, 4th ed)

Measurement of distances or movements by means of the phenomena caused by the interference of two rays of light (optical interferometry) or of sound (acoustic interferometry).

Behavior of LIGHT and its interactions with itself and materials.

Water swollen, rigid, 3-dimensional network of cross-linked, hydrophilic macromolecules, 20-95% water. They are used in paints, printing inks, foodstuffs, pharmaceuticals, and cosmetics. (Grant & Hackh's Chemical Dictionary, 5th ed)

A technique that localizes specific nucleic acid sequences within intact chromosomes, eukaryotic cells, or bacterial cells through the use of specific nucleic acid-labeled probes.

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.

The only family of the order SCANDENTIA, variously included in the order Insectivora or in the order Primates, and often in the order Microscelidea, consisting of five genera. They are TUPAIA, Ananthana (Indian tree shrew), Dendrogale (small smooth-tailed tree shrew), Urogale (Mindanao tree shrew), and Ptilocercus (pen-tailed tree shrew). The tree shrews inhabit the forest areas of eastern Asia from India and southwestern China to Borneo and the Philippines.

That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.

Methods of creating machines and devices.

Maf transcription factors are a family of basic-leucine zipper transcription factors that are closely related to V-MAF ONCOGENE PROTEIN. The C-MAF PROTO-ONCOGENE PROTEIN was the first mammalian Maf transcription factor identified, and now the family is known to include a variety of other Maf proteins such as MAFB TRANSCRIPTION FACTOR; MAFF TRANSCRIPTION FACTOR; MAFG TRANSCRIPTION FACTOR; and MAFK TRANSCRIPTION FACTOR.

Connections between cells which allow passage of small molecules and electric current. Gap junctions were first described anatomically as regions of close apposition between cells with a narrow (1-2 nm) gap between cell membranes. The variety in the properties of gap junctions is reflected in the number of CONNEXINS, the family of proteins which form the junctions.

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 superorder in the class CEPHALOPODA, consisting of the orders Octopoda (octopus) with over 200 species and Vampyromorpha with a single species. The latter is a phylogenetic relic but holds the key to the origins of Octopoda.

The absence or restriction of the usual external sensory stimuli to which the individual responds.

The aperture in the iris through which light passes.

One of a group of nonenzymatic reactions in which aldehydes, ketones, or reducing sugars react with amino acids, peptides, or proteins. Food browning reactions, such as those that occur with cooking of meats, and also food deterioration reactions, resulting in decreased nutritional value and color changes, are attributed to this reaction type. The Maillard reaction is studied by scientists in the agriculture, food, nutrition, and carbohydrate chemistry fields.

A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.

Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.

The condition of where images are correctly brought to a focus on the retina.

Personal devices for protection of the eyes from impact, flying objects, glare, liquids, or injurious radiation.

Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

Proteins encoded by homeobox genes (GENES, HOMEOBOX) that exhibit structural similarity to certain prokaryotic and eukaryotic DNA-binding proteins. Homeodomain proteins are involved in the control of gene expression during morphogenesis and development (GENE EXPRESSION REGULATION, DEVELOPMENTAL).

The outer of the three germ layers of an embryo.

Processes and properties of the EYE as a whole or of any of its parts.

Measurement of light given off by fluorescein in order to assess the integrity of various ocular barriers. The method is used to investigate the blood-aqueous barrier, blood-retinal barrier, aqueous flow measurements, corneal endothelial permeability, and tear flow dynamics.

Experimentally produced harmful effects of ionizing or non-ionizing RADIATION in CHORDATA animals.

Stratified squamous epithelium that covers the outer surface of the CORNEA. It is smooth and contains many free nerve endings.

Elements of limited time intervals, contributing to particular results or situations.

Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.

A biocompatible, hydrophilic, inert gel that is permeable to tissue fluids. It is used as an embedding medium for microscopy, as a coating for implants and prostheses, for contact lenses, as microspheres in adsorption research, etc.

Filaments 7-11 nm in diameter found in the cytoplasm of all cells. Many specific proteins belong to this group, e.g., desmin, vimentin, prekeratin, decamin, skeletin, neurofilin, neurofilament protein, and glial fibrillary acid protein.

Deeply perforating or puncturing type intraocular injuries.

Sterile solutions that are intended for instillation into the eye. It does not include solutions for cleaning eyeglasses or CONTACT LENS SOLUTIONS.

Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.

Removal of the whole or part of the vitreous body in treating endophthalmitis, diabetic retinopathy, retinal detachment, intraocular foreign bodies, and some types of glaucoma.

The disodium salt of selenious acid. It is used therapeutically to supply the trace element selenium and is prepared by the reaction of SELENIUM DIOXIDE with SODIUM HYDROXIDE.

Electrophoresis in which a second perpendicular electrophoretic transport is performed on the separate components resulting from the first electrophoresis. This technique is usually performed on polyacrylamide gels.

The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.

Suppurative inflammation of the tissues of the internal structures of the eye frequently associated with an infection.

Surgical removal of a section of the iris.

A tripeptide with many roles in cells. It conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides.

An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.

The professional practice of primary eye and vision care that includes the measurement of visual refractive power and the correction of visual defects with lenses or glasses.

Inanimate objects that become enclosed in the eye.

Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.

Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

The physiological renewal, repair, or replacement of tissue.

Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

The presence of an infectious agent on instruments, prostheses, or other inanimate articles.

Disorder occurring in the central or peripheral area of the cornea. The usual degree of transparency becomes relatively opaque.

The distance between the anterior and posterior poles of the eye, measured either by ULTRASONOGRAPHY or by partial coherence interferometry.

A polyhydric alcohol with about half the sweetness of sucrose. Sorbitol occurs naturally and is also produced synthetically from glucose. It was formerly used as a diuretic and may still be used as a laxative and in irrigating solutions for some surgical procedures. It is also used in many manufacturing processes, as a pharmaceutical aid, and in several research applications.

Refers to animals in the period of time just after birth.

Partial or total replacement of all layers of a central portion of the cornea.

Each of the upper and lower folds of SKIN which cover the EYE when closed.

Histochemical localization of immunoreactive substances using labeled antibodies as reagents.

The use of photothermal effects of LASERS to coagulate, incise, vaporize, resect, dissect, or resurface tissue.

A family of sequence-related proteins similar to HMGB1 PROTEIN that contains specific HMG-BOX DOMAINS.

The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.

A mass spectrometric technique that is used for the analysis of large biomolecules. Analyte molecules are embedded in an excess matrix of small organic molecules that show a high resonant absorption at the laser wavelength used. The matrix absorbs the laser energy, thus inducing a soft disintegration of the sample-matrix mixture into free (gas phase) matrix and analyte molecules and molecular ions. In general, only molecular ions of the analyte molecules are produced, and almost no fragmentation occurs. This makes the method well suited for molecular weight determinations and mixture analysis.

OPPORTUNISTIC INFECTIONS with the soil fungus FUSARIUM. Typically the infection is limited to the nail plate (ONYCHOMYCOSIS). The infection can however become systemic especially in an IMMUNOCOMPROMISED HOST (e.g., NEUTROPENIA) and results in cutaneous and subcutaneous lesions, fever, KERATITIS, and pulmonary infections.

Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.

The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

The sum of the weight of all the atoms in a molecule.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

Rendering pathogens harmless through the use of heat, antiseptics, antibacterial agents, etc.

The complex processes of initiating CELL DIFFERENTIATION in the embryo. The precise regulation by cell interactions leads to diversity of cell types and specific pattern of organization (EMBRYOGENESIS).

The plan and delineation of prostheses in general or a specific prosthesis.

The use of an aberrometer to measure eye tissue imperfections or abnormalities based on the way light passes through the eye which affects the ability of the eye to focus properly.

A species of baboon in the family CERCOPITHECIDAE, which has a well-studied trilevel social structure consisting of troops, bands, and clans.

Agents causing contraction of the pupil of the eye. Some sources use the term miotics only for the parasympathomimetics but any drug used to induce miosis is included here.

Bleeding in the anterior chamber of the eye.

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).

A naturally occurring product of plants obtained following reduction of GALACTOSE. It appears as a white crystalline powder with a slight sweet taste. It may form in excess in the lens of the eye in GALACTOSEMIAS, a deficiency of GALACTOKINASE.

The mucous membrane that covers the posterior surface of the eyelids and the anterior pericorneal surface of the eyeball.

The protein components of ferritins. Apoferritins are shell-like structures containing nanocavities and ferroxidase activities. Apoferritin shells are composed of 24 subunits, heteropolymers in vertebrates and homopolymers in bacteria. In vertebrates, there are two types of subunits, light chain and heavy chain. The heavy chain contains the ferroxidase activity.

A subclass of SOX transcription factors that are expressed in neuronal tissue where they may play a role in the regulation of CELL DIFFERENTIATION. Members of this subclass are generally considered to be transcriptional activators.

Examination of the angle of the anterior chamber of the eye with a specialized optical instrument (gonioscope) or a contact prism lens.

An objective determination of the refractive state of the eye (NEARSIGHTEDNESS; FARSIGHTEDNESS; ASTIGMATISM). By using a RETINOSCOPE, the amount of correction and the power of lens needed can be determined.

Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.

Shiny, flexible bands of fibrous tissue connecting together articular extremities of bones. They are pliant, tough, and inextensile.

A group of inherited enzyme deficiencies which feature elevations of GALACTOSE in the blood. This condition may be associated with deficiencies of GALACTOKINASE; UDPGLUCOSE-HEXOSE-1-PHOSPHATE URIDYLYLTRANSFERASE; or UDPGLUCOSE 4-EPIMERASE. The classic form is caused by UDPglucose-Hexose-1-Phosphate Uridylyltransferase deficiency, and presents in infancy with FAILURE TO THRIVE; VOMITING; and INTRACRANIAL HYPERTENSION. Affected individuals also may develop MENTAL RETARDATION; JAUNDICE; hepatosplenomegaly; ovarian failure (PRIMARY OVARIAN INSUFFICIENCY); and cataracts. (From Menkes, Textbook of Child Neurology, 5th ed, pp61-3)

The pressure of the fluids in the eye.

An in situ method for detecting areas of DNA which are nicked during APOPTOSIS. Terminal deoxynucleotidyl transferase is used to add labeled dUTP, in a template-independent manner, to the 3 prime OH ends of either single- or double-stranded DNA. The terminal deoxynucleotidyl transferase nick end labeling, or TUNEL, assay labels apoptosis on a single-cell level, making it more sensitive than agarose gel electrophoresis for analysis of DNA FRAGMENTATION.

Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.

Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.

A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.

The science dealing with the establishment and maintenance of health in the individual and the group. It includes the conditions and practices conducive to health. (Webster, 3d ed)

An exotic species of the family CYPRINIDAE, originally from Asia, that has been introduced in North America. They are used in embryological studies and to study the effects of certain chemicals on development.

An enzyme that catalyzes the active transport system of sodium and potassium ions across the cell wall. Sodium and potassium ions are closely coupled with membrane ATPase which undergoes phosphorylation and dephosphorylation, thereby providing energy for transport of these ions against concentration gradients.

A genus of tree shrews of the family TUPAIIDAE which consists of about 12 species. One of the most frequently encountered species is T. glis. Members of this genus inhabit rain forests and secondary growth areas in southeast Asia.

The development of anatomical structures to create the form of a single- or multi-cell organism. Morphogenesis provides form changes of a part, parts, or the whole organism.

A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.

An intermediate filament protein found in most differentiating cells, in cells grown in tissue culture, and in certain fully differentiated cells. Its insolubility suggests that it serves a structural function in the cytoplasm. MW 52,000.

A family of small polypeptide growth factors that share several common features including a strong affinity for HEPARIN, and a central barrel-shaped core region of 140 amino acids that is highly homologous between family members. Although originally studied as proteins that stimulate the growth of fibroblasts this distinction is no longer a requirement for membership in the fibroblast growth factor family.

Organic siloxanes which are polymerized to the oily stage. The oils have low surface tension and density less than 1. They are used in industrial applications and in the treatment of retinal detachment, complicated by proliferative vitreoretinopathy.

Cysteine proteinase found in many tissues. Hydrolyzes a variety of endogenous proteins including NEUROPEPTIDES; CYTOSKELETAL PROTEINS; proteins from SMOOTH MUSCLE; CARDIAC MUSCLE; liver; platelets; and erythrocytes. Two subclasses having high and low calcium sensitivity are known. Removes Z-discs and M-lines from myofibrils. Activates phosphorylase kinase and cyclic nucleotide-independent protein kinase. This enzyme was formerly listed as EC 3.4.22.4.

Making measurements by the use of stereoscopic photographs.

An imaging method using LASERS that is used for mapping subsurface structure. When a reflective site in the sample is at the same optical path length (coherence) as the reference mirror, the detector observes interference fringes.

The role of optical defocus in regulating refractive development in infant monkeys. (1/242)

Early in life, the two eyes of infant primates normally grow in a coordinated manner toward the ideal refractive state. We investigated the extent to which lens-induced changes in the effective focus of the eye affected refractive development in infant rhesus monkeys. The main finding was that spectacle lenses could predictably alter the growth of one or both eyes resulting in appropriate compensating refractive changes in both the hyperopic and myopic directions. Although the effective operating range of the emmetropization process in young monkeys is somewhat limited, the results demonstrate that emmetropization in this higher primate, as in a number of other species, is an active process that is regulated by optical defocus associated with the eye's effective refractive state. (+info)

The growing eye: an autofocus system that works on very poor images. (2/242)

It is unknown which retinal image features are analyzed to control axial eye growth and refractive development. On the other hand, identification of these features is fundamental for the understanding of visually acquired refractive errors. Cyclopleged chicks were individually kept in the center of a drum with only one viewing distance possible. Defocusing spectacle lenses were used to stimulate the retina with defined defocus of similar magnitude but different sign. If spatial frequency content and contrast were the only cues analyzed by the retina, all chicks should have become myopic. However, compensatory eye growth was still always in the right direction. The most likely cues for emmetropization, spatial frequency content and image contrast, do therefore not correlate with the elongation of the eye. Rather, the sign of defocus was extracted even from very poor images. (+info)

Long-term changes in retinal contrast sensitivity in chicks from frosted occluders and drugs: relations to myopia? (3/242)

Experiments in animal models have shown that the retinal analyzes the image to identify the position of the plane of focus and fine-tunes the growth of the underlying sclera. It is fundamental to the understanding of the development of refractive errors to know which image features are processed. Since the position of the image plane fluctuates continuously with accommodative status and viewing distance, a meaningful control of refractive development can only occur by an averaging procedure with a long time constant. As a candidate for a retinal signal for enhanced eye growth and myopia we propose the level of contrast adaptation which varies with the average amount of defocus. Using a behavioural paradigm, we have found in chickens (1) that contrast adaptation (CA, here referred to as an increase in contrast sensitivity) occurs at low spatial frequencies (0.2 cyc/deg) already after 1.5 h of wearing frosted goggles which cause deprivation myopia, (2) that CA also occurs with negative lenses (-7.4D) and positive lenses (+6.9D) after 1.5 h, at least if accommodation is paralyzed and, (3) that CA occurs at a retinal level or has, at least, a retinal component. Furthermore, we have studied the effects of atropine and reserpine, which both suppress myopia development, on CA. Quisqualate, which causes retinal degeneration but leaves emmetropization functional, was also tested. We found that both atropine and reserpine increase contrast sensitivity to a level where no further CA could be induced by frosted goggles. Quisqualate increased only the variability of refractive development and of contrast sensitivity. Taken together, CA occurring during extended periods of defocus is a possible candidate for a retinal error signal for myopia development. However, the situation is complicated by the fact that there must be a second image processing mode generating a powerful inhibitory growth signal if the image is in front of the retina, even with poor images (Diether, S., & Schaeffel, F. (1999). (+info)

The response to prism deviations in human infants. (4/242)

Previous research has suggested that infants are unable to make a corrective eye movement in response to a small base-out prism placed in front of one eye before 14-16 weeks [1]. Three hypotheses have been proposed to explain this early inability, and each of these makes different predictions for the time of onset of a response to a larger prism. The first proposes that infants have a 'degraded sensory capacity' and so require a larger retinal disparity (difference in the position of the image on the retina of each eye) to stimulate disparity detectors [2]. This predicts that infants might respond at an earlier age than previously reported [1] when tested using a larger prism. The second hypothesis proposes that infants learn to respond to larger retinal disparities through practice with small disparities [3]. According to this theory, using a larger prism will not result in developmentally earlier responses, and may even delay the response. The third hypothesis proposes that the ability to respond to prismatic deviation depends on maturational factors indicated by the onset of stereopsis (the ability to detect depth in an image on the basis of retinal disparity cues only) [4] [5], predicting that the size of the prism is irrelevant. To differentiate between these hypotheses, we tested 192 infants ranging from 2 to 52 weeks of age using a larger prism. Results showed that 63% of infants of 5-8 weeks of age produced a corrective eye movement in response to placement of a prism in front of the eye when in the dark. Both the percentage of infants who produced a response, and the speed of the response, increased with age. These results suggest that infants can make corrective eye movements in response to large prismatic deviations before 14-16 weeks of age. This, in combination with other recent results [6], discounts previous hypotheses. (+info)

Recent developments in clinical photography. (5/242)

A system comprising a clinical camera, specialized retractors, and a new occlusal mirror are described to maximize the quality of both intra-oral and extra-oral photography in the multi-user situation. (+info)

Effect of adaptation to telescopic spectacles on the initial human horizontal vestibuloocular reflex. (6/242)

Gain of the vestibuloocular reflex (VOR) not only varies with target distance and rotational axis, but can be chronically modified in response to prolonged wearing of head-mounted magnifiers. This study examined the effect of adaptation to telescopic spectacles on the variation of the VOR with changes in target distance and yaw rotational axis for head velocity transients having peak accelerations of 2,800 and 1,000 degrees /s(2). Eye and head movements were recorded with search coils in 10 subjects who underwent whole body rotations around vertical axes that were 10 cm anterior to the eyes, centered between the eyes, between the otoliths, or 20 cm posterior to the eyes. Immediately before each rotation, subjects viewed a target 15 or 500 cm distant. Lighting was extinguished immediately before and was restored after completion of each rotation. After initial rotations, subjects wore 1.9x magnification binocular telescopic spectacles during their daily activities for at least 6 h. Test spectacles were removed and measurement rotations were repeated. Of the eight subjects tolerant of adaptation to the telescopes, six demonstrated VOR gain enhancement after adaptation, while gain in two subjects was not increased. For all subjects, the earliest VOR began 7-10 ms after onset of head rotation regardless of axis eccentricity or target distance. Regardless of adaptation, VOR gain for the proximate target exceeded that for the distant target beginning at 20 ms after onset of head rotation. Adaptation increased VOR gain as measured 90-100 ms after head rotation onset by an average of 0.12 +/- 0.02 (SE) for the higher head acceleration and 0.19 +/- 0.02 for the lower head acceleration. After adaptation, four subjects exhibited significant increases in the canal VOR gain only, whereas two subjects exhibited significant increases in both angular and linear VOR gains. The latencies of linear and early angular target distance effects on VOR gain were unaffected by adaptation. The earliest significant change in angular VOR gain in response to adaptation occurred 50 and 68 ms after onset of the 2,800 and 1,000 degrees /s(2) peak head accelerations, respectively. The latency of the adaptive increase in linear VOR gain was approximately 50 ms for the peak head acceleration of 2,800 degrees /s(2), and 100 ms for the peak head acceleration of 1,000 degrees /s(2). Thus VOR gain changes and latency were consistent with modification in the angular VOR in most subjects, and additionally in the linear VOR in a minority of subjects. (+info)

Clinical effect of low vision aids. (7/242)

The number of patients with low vision is increasing as life expectancy increases. In addition, the interest and demand for low vision aids are also increasing with improved socioeconomic status and the development of mass media. Therefore, it is imperative to recognize the importance of low vision aids. We reviewed the clinical records of 118 patients who visited our low vision clinic more than twice. According to the data analyzed, optic nerve atrophy, retinal degeneration, diabetic retinopathy and age-related macular degeneration were the most common causes of low vision in these patients. The best corrected visual acuities without low vision aids were less than 0.3, but with the help of low vision aids, vision improved to more than 0.4 in 87% of the patients for near vision, and 56% for distant vision. The patients had complained that they could not read books, see a blackboard, recognize a person at a distance, and had other problems because of low vision. However, with the use of low vision aids their satisfaction with their vision rose to 70%. Hand magnifiers, high-powered spectacle lenses, and stand magnifiers were the low vision aids commonly used by people for near vision, while the Galilean telescope and Keplerian telescope were the most popular devices used for distant vision. In conclusion, low vision aids are very helpful devices to patients with low vision. (+info)

Form-deprivation myopia in monkeys is a graded phenomenon. (8/242)

To shed light on the potential role of the phenomenon of form-deprivation myopia in normal refractive development, we investigated the degree of image degradation required to produce axial myopia in rhesus monkeys. Starting at about 3 weeks of age, diffuser spectacle lenses were employed to degrade the retinal image in one eye of 13 infant monkeys. The diffusers were worn continuously for periods ranging between 11 and 19 weeks. The effects of three different strengths of optical diffusers, which produced reductions in image contrast that ranged from about 0.5 to nearly 3 log units, were assessed by retinoscopy and A-scan ultrasonography. Control data were obtained from ten normal infants and three infants reared with clear, zero-powered lenses over both eyes. Eleven of the 13 treated infants developed form-deprivation myopia. Qualitatively similar results were obtained for the three diffuser groups, however, the degree of axial myopia varied directly with the degree of image degradation. Thus, form-deprivation myopia in monkeys is a graded phenomenon and can be triggered by a modest degree of chronic image degradation. (+info)

There are several types of lens diseases or disorders, including:

1. Cataracts: A clouding of the lens that can cause blurred vision, double vision, and sensitivity to light. It is one of the most common causes of vision loss in older adults.
2. Astigmatism: An irregularly shaped lens that can cause blurred or distorted vision at all distances.
3. Presbyopia: A age-related condition that affects the lens' ability to accommodate, making it difficult to focus on close objects.
4. Dyslexia: A condition where the eye's lens is unable to properly focus images, leading to blurred or distorted vision.
5. Lens subluxation: A condition where the lens becomes dislocated and pushes against the iris, causing pain and blurred vision.
6. Lens luxation: A condition where the lens is completely dislocated from its normal position and can cause blindness if left untreated.
7. Traumatic cataract: A cataract that develops after an eye injury.
8. Congenital cataract: A cataract that is present at birth.
9. Secondary cataract: A cataract that develops as a complication of another eye condition, such as uveitis or diabetes.
10. Lens opacification: A clouding of the lens that can cause blurred vision and is often seen in people with diabetes or other systemic conditions.

These are some of the most common types of lens diseases, but there are others that can affect the lens of the eye as well. Treatment for lens diseases can range from glasses or contact lenses to surgery, depending on the severity and type of condition. Regular eye exams are important for early detection and treatment of these conditions to prevent vision loss.

There are different types of cataracts, including:

1. Nuclear cataract: This is the most common type of cataract and affects the center of the lens.
2. Cortical cataract: This type of cataract affects the outer layer of the lens and can cause a "halo" effect around lights.
3. Posterior subcapsular cataract: This type of cataract affects the back of the lens and is more common in younger people and those with diabetes.
4. Congenital cataract: This type of cataract is present at birth and can be caused by genetic factors or other conditions.

Symptoms of cataracts can include:

* Blurred vision
* Double vision
* Sensitivity to light
* Glare
* Difficulty seeing at night
* Fading or yellowing of colors

Cataracts can be diagnosed with a comprehensive eye exam, which includes a visual acuity test, dilated eye exam, and imaging tests such as ultrasound or optical coherence tomography (OCT).

Treatment for cataracts typically involves surgery to remove the clouded lens and replace it with an artificial one called an intraocular lens (IOL). The type of IOL used will depend on the patient's age, visual needs, and other factors. In some cases, cataracts may be removed using a laser-assisted procedure.

In addition to surgery, there are also non-surgical treatments for cataracts, such as glasses or contact lenses, which can help improve vision. However, these treatments do not cure the underlying condition and are only temporary solutions.

It's important to note that cataracts are a common age-related condition and can affect anyone over the age of 40. Therefore, it's important to have regular eye exams to monitor for any changes in vision and to detect cataracts early on.

In summary, cataracts are a clouding of the lens in the eye that can cause blurred vision, double vision, sensitivity to light, and other symptoms. Treatment typically involves surgery to remove the clouded lens and replace it with an artificial one, but non-surgical treatments such as glasses or contact lenses may also be used. Regular eye exams are important for detecting cataracts early on and monitoring vision health.

Lens subluxation is a condition where the crystalline lens of the eye partially or completely dislocates from its normal position behind the iris, causing visual impairment and potential vision loss. It can occur due to various causes such as trauma, inflammation, or degenerative changes.

The term "subluxation" means a partial dislocation of a structure, and in the context of the crystalline lens, it refers to the displacement of the lens from its normal position in the eye.

Lens subluxation can be classified into several types based on the location and extent of the displacement:

1. Posterior subluxation: The lens is displaced backward, away from the iris.
2. Anterior subluxation: The lens is displaced forward, towards the iris.
3. Total subluxation: The lens is completely dislocated from its normal position.

Symptoms of lens subluxation can include blurred vision, double vision, eye pain, and sensitivity to light. Treatment options depend on the severity and cause of the condition, and may include glasses or contact lenses, medication, or surgery.

In summary, lens subluxation is a condition where the crystalline lens of the eye partially or completely dislocates from its normal position, leading to visual impairment and potential vision loss. It can occur due to various causes and can be classified into several types based on the location and extent of the displacement.

The term "presbyopia" comes from the Greek words "presbys," meaning "old," and "ops," meaning "eye." It was first described by the English physician and surgeon Thomas Wharton in 1655, and has since become a widely recognized condition in the field of ophthalmology.

Presbyopia is caused by a loss of elasticity in the lens of the eye, which makes it less able to change shape and focus on close objects. This can be exacerbated by other age-related changes such as cataracts, glaucoma, or macular degeneration.

Symptoms of presbyopia include difficulty reading or performing other close-up tasks, headaches or eye strain from trying to focus, and blurred vision. Treatment options for presbyopia include corrective lenses such as glasses or contact lenses, bifocal or multifocal lenses, or surgical procedures such as refractive surgery or intraocular lens implantation.

Overall, presbyopia is a common and treatable condition that can significantly impact an individual's quality of life, particularly as they age. It is important for individuals to have regular eye exams to monitor their vision and address any changes in their eyesight over time.

Definition: Aphakia is a congenital or acquired condition characterized by the absence of the crystalline lens in one or both eyes. It can be classified into different types based on the severity and location of the defect.

Types of Aphakia:

1. Microphthalmia: This type of aphakia is characterized by a small eye that may or may not have a lens.
2. Anophthalmia: This is the most severe form of aphakia where one or both eyes are completely absent.
3. Coloboma: This type of aphakia is characterized by a hole in one of the structures of the eye, such as the iris or retina.

Causes: Aphakia can be caused by genetic mutations, acquired injuries, or infections during pregnancy or childhood. Some of the known causes of aphakia include:

1. Genetic disorders: Certain genetic conditions, such as Turner syndrome, can increase the risk of developing aphakia.
2. Infections: Infections such as rubella or toxoplasmosis during pregnancy can increase the risk of aphakia in the developing fetus.
3. Trauma: Injuries to the eye or head can cause aphakia, especially if they occur during childhood.
4. Tumors: Certain tumors, such as retinoblastoma, can cause aphakia if left untreated.

Symptoms: The symptoms of aphakia can vary depending on the severity of the condition and the age of onset. Some common symptoms include:

1. Blindness or vision loss in one or both eyes
2. Abnormal head positioning or posture
3. Difficulty with depth perception
4. Squinting or tilting the head to see objects clearly
5. Increased sensitivity to light
6. Lazy eye (amblyopia)
7. Poor pupillary reflex
8. Abnormal retinal development
9. Increased risk of other ocular abnormalities, such as cataracts or glaucoma

Diagnosis: Aphakia can be diagnosed through a comprehensive eye exam, including a visual acuity test, refraction test, and ophthalmoscopy. Imaging tests, such as ultrasound or MRI, may also be used to evaluate the structure of the eye and detect any underlying conditions.

Treatment: The treatment for aphakia depends on the severity of the condition and the age of onset. Some possible treatments include:

1. Glasses or contact lenses: To correct refractive errors and improve vision.
2. Patching: To strengthen the weaker eye and improve amblyopia.
3. Atropine therapy: To reduce the amount of accommodation and improve alignment of the eyes.
4. Orthoptic exercises: To improve eye movement and alignment.
5. Surgery: To correct refractive errors, align the eyes properly, or remove any cataracts or other ocular abnormalities.
6. Prosthetic implantation: In some cases, a prosthetic eye may be recommended to restore the natural appearance of the eye and improve vision.

Prognosis: The prognosis for aphakia varies depending on the severity of the condition and the age of onset. In general, early diagnosis and treatment can improve the chances of successful management and a good visual outcome. However, some individuals with aphakia may experience long-term vision loss or other complications, such as amblyopia or glaucoma. Regular follow-up with an eye care professional is important to monitor the condition and adjust treatment as needed.

Myopia can be caused by a variety of factors, including:

1. Genetics: Myopia can run in families, and people with a family history of myopia are more likely to develop the condition.
2. Near work: Spending too much time doing close-up activities such as reading or using digital devices can increase the risk of developing myopia.
3. Poor posture: Slouching or leaning forward can cause the eye to focus incorrectly, leading to myopia.
4. Nutritional deficiencies: A diet lacking in essential nutrients such as vitamin D and omega-3 fatty acids may contribute to the development of myopia.
5. Eye stress: Prolonged eye strain due to excessive near work or other activities can lead to myopia.

Symptoms of myopia include:

1. Difficulty seeing distant objects clearly
2. Headaches or eye strain from trying to focus on distant objects
3. Squinting or rubbing the eyes to try to see distant objects more clearly
4. Difficulty seeing in low light conditions
5. Blurry vision at a distance, with close objects appearing clear.

Myopia can be diagnosed with a comprehensive eye exam, which includes a visual acuity test, refraction test, and retinoscopy. Treatment options for myopia include:

1. Glasses or contact lenses: These corrective lenses refract light properly onto the retina, allowing clear vision of both close and distant objects.
2. Laser eye surgery: Procedures such as LASIK can reshape the cornea to improve its curvature and reduce myopia.
3. Orthokeratology (ORTHO-K): A non-surgical procedure that uses a specialized contact lens to reshape the cornea while you sleep.
4. Myopia control: This involves using certain treatments or techniques to slow down the progression of myopia in children and young adults.
5. Multifocal lenses: These lenses have multiple focal points, allowing for clear vision of both near and distant objects without the need for glasses or contact lenses.

In conclusion, myopia is a common vision condition that can be caused by a variety of factors and symptoms can include difficulty seeing distant objects clearly, headaches, and eye strain. Treatment options include glasses or contact lenses, laser eye surgery, ORTHO-K, myopia control, and multifocal lenses. It is important to consult an eye doctor for a comprehensive evaluation and to determine the best course of treatment for your specific case of myopia.

Hyperopia, also known as farsightedness, is a common vision condition in which close objects appear blurry while distant objects appear clear. This occurs when the eyeball is shorter than normal or the cornea is not curved enough, causing light rays to focus behind the retina rather than directly on it. Hyperopia can be treated with glasses, contact lenses, or refractive surgery.

Word origin: Greek "hyper" (beyond) + "ops" (eye) + -ia (suffix denoting a condition or state)

First recorded use: 1690s

Myopia occurs when the eyeball is too long or the cornea is too steep, causing light to focus in front of the retina instead of directly on it. Hyperopia is the opposite, where the eyeball is too short or the cornea is too flat, causing light to focus behind the retina. Astigmatism is caused by an irregularly shaped cornea, which causes light to focus at multiple points instead of one. Presbyopia is a loss of near vision that occurs as people age, making it harder to see close objects clearly.

In addition to these common refractive errors, there are other, less common conditions that can affect the eyes and cause blurred vision, such as amblyopia (lazy eye), strabismus (crossed eyes), and retinal detachment. These conditions can be caused by a variety of factors, including genetics, injury, or disease.

Refractive errors can have a significant impact on daily life, affecting everything from work and school performance to social interactions and overall quality of life. Fortunately, with the help of corrective lenses or surgery, many people are able to achieve clear vision and lead fulfilling lives.

Pseudophakia is considered a rare condition, as most cataract surgeries involve removal of the entire natural lens. However, there are certain situations where leaving behind some residual lens material can be beneficial, such as in cases where the patient has severe astigmatism or presbyopia (age-related loss of near vision).

The presence of pseudophakia can affect the visual outcome and refractive status of the eye, and may require additional surgical intervention to optimize visual acuity. It is important for ophthalmologists to be aware of this condition and consider it when evaluating patients with cataracts or other eye conditions.

Synonyms for Aphakia, postcataract include:

* Postoperative aphakia
* Postcataract aphakia
* Aphakic vision loss
* Blindness following cataract surgery

Causes and risk factors for Aphakia, postcataract:

* Cataract surgery: The most common cause of aphakia, postcataract is complications from cataract surgery. During the procedure, the natural lens of the eye may be damaged or removed accidentally.
* Infection: Infections after cataract surgery can cause inflammation and damage to the eye, leading to aphakia.
* Vitreous loss: During cataract surgery, the vitreous gel in the eye may be disturbed or lost, leading to vision loss.

Symptoms of Aphakia, postcataract:

* Blindness or vision loss
* Difficulty seeing objects clearly
* Double vision or ghosting
* Sensitivity to light
* Reduced peripheral vision

Diagnosis and treatment of Aphakia, postcataract:

* Comprehensive eye exam: An ophthalmologist will perform a comprehensive eye exam to determine the cause of the aphakia and assess the extent of vision loss.
* Visual acuity testing: The ophthalmologist will perform visual acuity tests to measure the patient's ability to see objects clearly.
* Retinal imaging: Imaging tests such as ultrasound or MRI may be used to evaluate the retina and diagnose any underlying conditions.
* Glasses or contact lenses: In some cases, glasses or contact lenses may be prescribed to improve vision.
* Intracorneal implant: An intracorneal implant may be recommended to improve vision in cases where the natural lens has been removed and there is no cataract present.
* Corneal transplant: In severe cases of aphakia, a corneal transplant may be necessary to restore vision.

Prevention of Aphakia, postcataract:

* Early detection and treatment of cataracts: Regular eye exams can help detect cataracts early, which can improve the chances of preserving vision and avoiding aphakia.
* Proper follow-up care after cataract surgery: Patients who have undergone cataract surgery should follow their postoperative instructions carefully and attend follow-up appointments to ensure that any complications are detected and treated promptly.
* Preventing eye injuries: Protective eyewear can help prevent eye injuries, which can lead to aphakia.

Prognosis of Aphakia, postcataract:
The prognosis for aphakia after cataract surgery is generally good if the condition is detected and treated promptly. With appropriate treatment, many patients can regain some or all of their vision. However, in severe cases or those with complications, the prognosis may be poorer.

It's important to note that aphakia is a rare complication of cataract surgery, and the vast majority of patients who undergo the procedure do not experience this condition. If you have undergone cataract surgery and are experiencing any unusual symptoms, it is important to seek medical attention promptly to ensure proper diagnosis and treatment.

Also known as: Corneal inflammation, Eye inflammation, Keratoconjunctivitis, Ocular inflammation.

Some common symptoms of corneal edema include:

* Blurred vision
* Haziness or clouding of the cornea
* Increased sensitivity to light
* Redness or discharge in the eye
* Pain or discomfort in the eye

Corneal edema can be diagnosed through a comprehensive eye exam, which may include a visual acuity test, dilated eye exam, and imaging tests such as cornea scans or ultrasound. Treatment for corneal edema depends on the underlying cause and may involve antibiotics, anti-inflammatory medications, or other therapies to reduce swelling and promote healing. In some cases, surgery may be necessary to remove scar tissue or improve drainage of fluid from the eye.

If left untreated, corneal edema can lead to more serious complications such as corneal ulcers or vision loss. Therefore, it is important to seek medical attention if you experience any symptoms of corneal edema to prevent any further damage and ensure proper treatment.

Astigmatism can occur in people of all ages and is usually present at birth, but it may not become noticeable until later in life. It may also develop as a result of an injury or surgery. Astigmatism can be corrected with glasses, contact lenses, or refractive surgery, such as LASIK.

There are different types of astigmatism, including:

1. Corneal astigmatism: This is the most common type of astigmatism and occurs when the cornea is irregularly shaped.
2. Lens astigmatism: This type of astigmatism occurs when the lens inside the eye is irregularly shaped.
3. Mixed astigmatism: This type of astigmatism occurs when both the cornea and lens are irregularly shaped.

Astigmatism can cause a range of symptoms, including:

* Blurred vision at all distances
* Distorted vision (such as seeing objects as being stretched out or blurry)
* Eye strain or fatigue
* Headaches or eye discomfort
* Squinting or tilting the head to see clearly

If you suspect you have astigmatism, it's important to see an eye doctor for a comprehensive eye exam. Astigmatism can be diagnosed with a visual acuity test and a retinoscopy, which measures the way the light enters the eye.

Astigmatism is a common vision condition that can be easily corrected with glasses, contact lenses, or refractive surgery. If you have astigmatism, it's important to seek professional treatment to improve your vision and reduce any discomfort or strain on the eyes.

The symptoms of microphthalmos may include:

* Small eyes with reduced visual acuity
* Difficulty with depth perception and peripheral vision
* Squinting or crossing of the eyes (strabismus)
* Poor eye movement
* Increased sensitivity to light (photophobia)
* Reduced pupillary reflexes

The causes of microphthalmos can include:

* Genetic mutations or chromosomal abnormalities
* Infections such as rubella, syphilis, or toxoplasmosis during pregnancy
* Maternal exposure to certain medications or chemicals during pregnancy
* Trauma or injury to the eye during fetal development
* Tumors or cysts in the eye or surrounding tissues

Diagnosis of microphthalmos typically involves a comprehensive eye exam, including measurements of the eye's size and visual acuity. Imaging tests such as ultrasound or MRI may also be used to evaluate the structure of the eye and surrounding tissues.

Treatment for microphthalmos depends on the underlying cause and severity of the condition. In some cases, corrective glasses or contact lenses may be sufficient to improve vision. Surgery may be necessary in more severe cases to realign the eyes or remove tumors or cysts. In cases where the microphthalmos is due to a genetic mutation, there may be no effective treatment other than managing the symptoms.

Treatment typically involves antiprotozoal medication, topical corticosteroids, and PVA (polyvinyl alcohol) membrane stripping. In severe cases, corneal transplantation may be necessary. Prophylactic antibiotics are not effective against Acanthamoeba infections, but contact precautions can help prevent transmission.

Prevention is key, and this includes proper hand washing and hygiene, avoiding exposure to water while wearing contact lenses, and using only sterile lens solutions. It is important for individuals who wear contact lenses to follow the recommended guidelines for their care and maintenance to reduce the risk of developing Acanthamoeba keratitis.

Overall, early diagnosis and appropriate treatment are essential to prevent long-term visual impairment and potential loss of vision in cases of Acanthamoeba keratitis.

The symptoms of a corneal ulcer may include:

* Pain or discomfort in the eye
* Redness and swelling of the eye
* Discharge or pus in the eye
* Blurred vision or sensitivity to light
* A feeling that there is something in the eye

If left untreated, a corneal ulcer can lead to complications such as:

* Perforation of the cornea
* Inflammation of the iris (iritis)
* Inflammation of the retina (retinitis)
* Vision loss or blindness

Treatment of a corneal ulcer typically involves antibiotic eye drops or ointments to treat any underlying bacterial infection, as well as supportive care to manage pain and promote healing. In severe cases, surgery may be necessary to remove the damaged tissue and promote healing.

Prevention of corneal ulcers includes good hygiene, proper use of contact lenses, and avoiding touching or rubbing the eyes. Early detection and treatment are key to preventing complications and preserving vision.

1. Keratoconus: This is a progressive thinning of the cornea that can cause it to bulge into a cone-like shape, leading to blurred vision and sensitivity to light.
2. Fuchs' dystrophy: This is a condition in which the cells in the innermost layer of the cornea become damaged, leading to clouding and blurred vision.
3. Bullous keratopathy: This is a condition in which there is a large, fluid-filled bubble on the surface of the cornea, which can cause blurred vision and discomfort.
4. Corneal ulcers: These are open sores on the surface of the cornea that can be caused by infection or other conditions.
5. Dry eye syndrome: This is a condition in which the eyes do not produce enough tears, leading to dryness, irritation, and blurred vision.
6. Corneal abrasions: These are scratches on the surface of the cornea that can be caused by injury or other conditions.
7. Trachoma: This is an infectious eye disease that can cause scarring and blindness if left untreated.
8. Ocular herpes: This is a viral infection that can cause blisters on the surface of the cornea and lead to scarring and vision loss if left untreated.
9. Endophthalmitis: This is an inflammation of the inner layer of the eye that can be caused by bacterial or fungal infections, and can lead to severe vision loss if left untreated.
10. Corneal neovascularization: This is the growth of new blood vessels into the cornea, which can be a complication of other conditions such as dry eye syndrome or ocular trauma.

These are just a few examples of the many different types of corneal diseases that can affect the eyes. It's important to seek medical attention if you experience any symptoms such as pain, redness, or blurred vision in one or both eyes. Early diagnosis and treatment can help prevent complications and preserve vision.

Capsule opacification refers to the clouding or whitening of the capsule that surrounds an implant, such as a surgical mesh or a joint replacement. This condition is caused by the accumulation of inflammatory cells, fibrosis, and/or mineral deposits within the capsule, which can lead to impaired functioning of the implant and surrounding tissues.

Causes:

There are several factors that can contribute to capsule opacification, including:

1. Infection: Bacterial or fungal infections can cause inflammation and accumulation of inflammatory cells within the capsule, leading to clouding or whitening.
2. Immune response: The body's immune system may respond to the presence of a foreign material (such as a surgical mesh or joint replacement) by producing inflammatory cells and tissue proliferation, which can lead to capsule opacification.
3. Mechanical stress: Prolonged mechanical stress on the implant, such as from excessive movement or pressure, can cause the accumulation of fibrosis and mineral deposits within the capsule, leading to clouding or whitening.
4. Poor surgical technique: Poor surgical technique or improper implant placement can lead to capsule opacification by causing inflammation and/or mechanical stress on the implant.

Symptoms:

Patients with capsule opacification may experience a range of symptoms, including:

1. Pain: Capsule opacification can cause pain in the affected area, which may be exacerbated by movement or activity.
2. Limited mobility: In severe cases, capsule opacification can lead to limited mobility and stiffness in the affected joint or tissue.
3. Swelling: Patients may experience swelling in the affected area due to inflammation and/or fluid accumulation.
4. Redness: The affected area may become red and warm to the touch, indicating inflammation.

Diagnosis:

Capsule opacification can be diagnosed using a range of imaging techniques, including:

1. X-rays: X-rays are commonly used to evaluate joint health and can help identify signs of capsule opacification, such as the presence of calcium deposits or bone spurs.
2. Ultrasound: Ultrasound imaging can provide detailed information about tissue structure and can help identify inflammation or fluid accumulation in the affected area.
3. MRI: Magnetic resonance imaging (MRI) can provide high-resolution images of soft tissues and can help diagnose capsule opacification by visualizing inflammation, fibrosis, or mineral deposits within the capsule.

Treatment:

The treatment for capsule opacification depends on the underlying cause and severity of the condition. Treatment options may include:

1. Medications: Anti-inflammatory medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or corticosteroids, can help reduce inflammation and relieve pain associated with capsule opacification.
2. Physical therapy: Physical therapy may be recommended to improve joint mobility and strength.
3. Joint injections: Injecting medications into the affected joint can help reduce inflammation and relieve pain.
4. Surgery: In severe cases of capsule opacification, surgery may be necessary to remove calcium deposits or repair damaged tissues.

Prevention:

Preventing capsule opacification involves addressing the underlying causes of the condition. Some preventive measures include:

1. Maintaining proper joint alignment and mechanics: Proper alignment and mechanics can help reduce the risk of joint injury and inflammation.
2. Engaging in regular exercise: Regular exercise can help maintain joint health and mobility.
3. Managing underlying conditions: Managing conditions such as osteoarthritis, gout, or rheumatoid arthritis can help prevent capsule opacification.
4. Avoiding excessive stress on the joints: Avoiding activities that place excessive stress on the joints can help reduce the risk of injury and inflammation.

There are many different types of eye diseases, including:

1. Cataracts: A clouding of the lens in the eye that can cause blurry vision and blindness.
2. Glaucoma: A group of diseases that damage the optic nerve and can lead to vision loss and blindness.
3. Age-related macular degeneration (AMD): A condition that causes vision loss in older adults due to damage to the macula, the part of the retina responsible for central vision.
4. Diabetic retinopathy: A complication of diabetes that can cause damage to the blood vessels in the retina and lead to vision loss.
5. Detached retina: A condition where the retina becomes separated from the underlying tissue, leading to vision loss.
6. Macular hole: A small hole in the macula that can cause vision loss.
7. Amblyopia (lazy eye): A condition where one eye is weaker than the other and has reduced vision.
8. Strabismus (crossed eyes): A condition where the eyes are not aligned properly and point in different directions.
9. Conjunctivitis: An inflammation of the conjunctiva, the thin membrane that covers the white part of the eye and the inside of the eyelids.
10. Dry eye syndrome: A condition where the eyes do not produce enough tears, leading to dryness, itchiness, and irritation.

Eye diseases can be caused by a variety of factors, including genetics, age, environmental factors, and certain medical conditions. Some eye diseases are inherited, while others are acquired through lifestyle choices or medical conditions.

Symptoms of eye diseases can include blurry vision, double vision, eye pain, sensitivity to light, and redness or inflammation in the eye. Treatment options for eye diseases depend on the specific condition and can range from medication, surgery, or lifestyle changes.

Regular eye exams are important for detecting and managing eye diseases, as many conditions can be treated more effectively if caught early. If you experience any symptoms of eye disease or have concerns about your vision, it is important to see an eye doctor as soon as possible.

While there is no cure for keratoconus, there are several treatment options available to help manage the condition. These include eyeglasses or contact lenses, specialized contact lenses called rigid gas permeable (RGP) lenses, and corneal transplantation in severe cases. Other treatments that may be recommended include phototherapeutic keratectomy (PTK), which involves removing damaged tissue from the cornea using a laser, or intacs, which are tiny plastic inserts that are placed into the cornea to flatten it and improve vision.

Keratoconus is relatively rare, affecting about 1 in every 2,000 people worldwide. However, it is more common in certain groups of people, such as those with a family history of the condition or those who have certain medical conditions, such as Down syndrome or sickle cell anemia. It typically affects both eyes, although one eye may be more severely affected than the other.

While there is no known cause for keratoconus, researchers believe that it may be linked to genetics, environmental factors, or a combination of both. The condition usually begins in adolescence or early adulthood and can progress over several years. In some cases, keratoconus can also be associated with other eye conditions, such as cataracts, glaucoma, or retinal detachment.

Some common types of eye abnormalities include:

1. Refractive errors: These are errors in the way the eye focuses light, causing blurry vision. Examples include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia (age-related loss of near vision).
2. Amblyopia: This is a condition where the brain favors one eye over the other, causing poor vision in the weaker eye.
3. Cataracts: A cataract is a clouding of the lens in the eye that can cause blurry vision and increase the risk of glaucoma.
4. Glaucoma: This is a group of eye conditions that can damage the optic nerve and lead to vision loss.
5. Macular degeneration: This is a condition where the macula, the part of the retina responsible for central vision, deteriorates, leading to vision loss.
6. Diabetic retinopathy: This is a complication of diabetes that can damage the blood vessels in the retina and lead to vision loss.
7. Retinal detachment: This is a condition where the retina becomes separated from the underlying tissue, leading to vision loss.
8. Corneal abnormalities: These are irregularities in the shape or structure of the cornea, such as keratoconus, that can cause blurry vision.
9. Optic nerve disorders: These are conditions that affect the optic nerve, such as optic neuritis, that can cause vision loss.
10. Traumatic eye injuries: These are injuries to the eye or surrounding tissue that can cause vision loss or other eye abnormalities.

Eye abnormalities can be diagnosed through a comprehensive eye exam, which may include visual acuity tests, refraction tests, and imaging tests such as retinal photography or optical coherence tomography (OCT). Treatment for eye abnormalities depends on the specific condition and may include glasses or contact lenses, medication, surgery, or other therapies.

Types of Eye Injuries:

1. Corneal abrasion: A scratch on the cornea, the clear outer layer of the eye.
2. Conjunctival bleeding: Bleeding in the conjunctiva, the thin membrane that covers the white part of the eye.
3. Hyphema: Blood in the space between the iris and the cornea.
4. Hemorrhage: Bleeding in the eyelid or under the retina.
5. Retinal detachment: Separation of the retina from the underlying tissue, which can cause vision loss if not treated promptly.
6. Optic nerve damage: Damage to the nerve that carries visual information from the eye to the brain, which can cause vision loss or blindness.
7. Orbital injury: Injury to the bones and tissues surrounding the eye, which can cause double vision, swelling, or vision loss.

Symptoms of Eye Injuries:

1. Pain in the eye or around the eye
2. Redness and swelling of the eye or eyelid
3. Difficulty seeing or blurred vision
4. Sensitivity to light
5. Double vision or loss of vision
6. Discharge or crusting around the eye
7. Swelling of the eyelids or face

Treatment of Eye Injuries:

1. Depending on the severity and nature of the injury, treatment may include antibiotics, pain relief medication, or surgery.
2. In some cases, a tube may be inserted into the eye to help drain fluid or prevent pressure from building up.
3. In severe cases, vision may not return completely, but there are many options for corrective glasses and contact lenses to improve remaining vision.
4. It is essential to seek medical attention immediately if there is a foreign object in the eye, as this can cause further damage if left untreated.
5. In cases of penetrating trauma, such as a blow to the eye, it is important to seek medical attention right away, even if there are no immediate signs of injury.
6. Follow-up appointments with an ophthalmologist are essential to monitor healing and address any complications that may arise.

Experimental radiation injuries are those that are intentionally caused in animal models or human subjects for research purposes, with the goal of understanding the effects of ionizing radiation on living organisms and developing treatments to mitigate these effects.

The study of experimental radiation injuries involves exposing animals or human subjects to varying levels of ionizing radiation and observing the resulting damage and recovery processes. This research has led to a better understanding of the mechanisms of radiation injury and the development of treatment strategies, such as blood transfusions and antioxidants, to mitigate the effects of radiation exposure.

Experimental radiation injuries are classified into two main types: acute and late-onset injuries. Acute radiation syndrome (ARS), also known as radiation sickness or radiation poisoning, occurs within hours to days after exposure and is characterized by nausea, vomiting, diarrhea, fatigue, and damage to the bone marrow, lungs, and gastrointestinal tract. Late-onset injuries, such as cancer and other chronic effects, can occur months or years after exposure and are caused by DNA damage and epigenetic changes.

Prevention of experimental radiation injuries is essential in reducing the risk of radiation exposure to humans and the environment. This includes using personal protective equipment, minimizing the use of ionizing radiation in medical procedures and research, and developing new technologies that reduce radiation exposure.

In summary, experimental radiation injuries are intentionally caused in animal models or human subjects for research purposes to understand the effects of ionizing radiation on living organisms and develop treatments to mitigate these effects. The study of experimental radiation injuries has led to a better understanding of the mechanisms of radiation injury and the development of treatment strategies, but prevention is essential in reducing the risk of radiation exposure.

There are several types of penetrating eye injuries, including:

1. Perforating injuries: These occur when an object punctures the globe of the eye, creating a hole in the retina or the sclera. These injuries can be life-threatening and require immediate medical attention.
2. Non-perforating injuries: These occur when an object does not penetrate the globe of the eye but still causes damage to the surrounding tissues. These injuries are typically less severe than perforating injuries but can still cause significant vision loss.
3. Hyphemas: These occur when blood collects in the space between the cornea and the iris, often due to a blow to the eye.
4. Retinal detachments: These occur when the retina becomes separated from the underlying tissue, often due to a traumatic injury.

Symptoms of penetrating eye injuries can include:

* Severe pain in the eye
* Redness and swelling of the affected eye
* Difficulty seeing or blindness
* Floaters or flashes of light
* A feeling of something in the eye

Treatment of penetrating eye injuries depends on the severity of the injury and can include:

1. Immediate medical attention to assess the extent of the injury and provide appropriate treatment.
2. Surgery to repair any damage to the eye, such as removing a foreign object or repairing a retinal detachment.
3. Antibiotics to prevent infection.
4. Pain management with medication.
5. Monitoring for complications, such as glaucoma or cataracts.

Preventive measures for penetrating eye injuries include:

1. Wearing protective eyewear when performing activities that could potentially cause eye injury, such as playing sports or working with power tools.
2. Avoiding touching the eyes or face to prevent the spread of infection.
3. Keeping the environment clean and free of hazards to reduce the risk of injury.
4. Properly storing and disposing of sharp objects to prevent accidents.
5. Seeking medical attention immediately if an eye injury occurs.

It is important to seek immediate medical attention if you experience any symptoms of a penetrating eye injury, as timely treatment can help prevent complications and improve outcomes.

Endophthalmitis can be classified into several types based on its causes, such as:

1. Postoperative endophthalmitis: This type of endophthalmitis occurs after cataract surgery or other intraocular surgeries. It is caused by bacterial infection that enters the eye through the surgical incision.
2. Endogenous endophthalmitis: This type of endophthalmitis is caused by an infection that originates within the eye, such as from a retinal detachment or uveitis.
3. Exogenous endophthalmitis: This type of endophthalmitis is caused by an infection that enters the eye from outside, such as from a penetrating injury or a foreign object in the eye.

The symptoms of endophthalmitis can include:

1. Severe pain in the eye
2. Redness and swelling of the conjunctiva
3. Difficulty seeing or blind spots in the visual field
4. Sensitivity to light
5. Increased sensitivity to touch or pressure on the eye
6. Fever and chills
7. Swollen lymph nodes
8. Enlarged pupil
9. Clouding of the vitreous humor

If you suspect that you or someone else has endophthalmitis, it is important to seek medical attention immediately. Early diagnosis and treatment can help prevent vision loss. Treatment options for endophthalmitis may include antibiotics, vitrectomy (removal of the vitreous humor), and in some cases, removal of the affected eye.

Types of Eye Foreign Bodies:

There are several types of eye foreign bodies, including:

1. Dust and small particles: These are the most common type of eye foreign body and can enter the eye through contact with the environment or by rubbing the eyes.
2. Large objects: These can include splinters, pen tips, or other small objects that become lodged in the eye.
3. Chemical irritants: Chemicals like household cleaners or pesticides can irritate the eyes and cause foreign body sensation.
4. Microorganisms: Bacteria, viruses, and other microorganisms can enter the eye and cause inflammation, which can lead to a foreign body sensation.

Symptoms of Eye Foreign Bodies:

The symptoms of an eye foreign body can vary depending on the size and location of the object, but common signs include:

1. Redness and irritation
2. Itching or burning sensation in the eye
3. Discharge or tearing
4. Blurred vision or sensitivity to light
5. Pain or discomfort in the eye

Diagnosis and Treatment of Eye Foreign Bodies:

If you suspect that you have an eye foreign body, it is important to seek medical attention as soon as possible. A healthcare professional will perform a thorough examination of the eye to locate the foreign body and determine the best course of treatment.

Treatment for eye foreign bodies may include:

1. Flushing the eye with water or saline solution to try to dislodge the object
2. Using antibiotic drops or ointments to prevent infection
3. Removing the object with a special instrument, such as a cotton swab or forceps
4. In severe cases, surgery may be necessary to remove the foreign body.

Prevention of Eye Foreign Bodies:

To prevent eye foreign bodies, it is important to take the following precautions:

1. Avoid touching or rubbing your eyes, as this can introduce bacteria and other contaminants into the eye.
2. Keep your hands and face clean, especially after handling chemicals or other potentially harmful substances.
3. Wear protective eyewear, such as goggles or safety glasses, when working with power tools or other equipment that can generate debris.
4. Avoid wearing contact lenses while swimming or in other wet environments.
5. Keep your home and work environment clean and free of clutter to reduce the risk of objects becoming lodged in the eye.

Conclusion:

Eye foreign bodies can cause a range of symptoms, from mild discomfort to serious vision loss. If you suspect that you have an object stuck in your eye, it is important to seek medical attention as soon as possible. With prompt diagnosis and appropriate treatment, most eye foreign bodies can be successfully removed and the risk of complications minimized. By taking precautions to prevent eye injuries and seeking immediate medical care if you experience any symptoms, you can help protect your vision and maintain good eye health.

1. Cutaneous fusariosis: This type of infection affects the skin and subcutaneous tissues, causing ulcers, nodules, and plaques.
2. Osteoarticular fusariosis: This type of infection affects the bones and joints, causing pain, swelling, and limited mobility.
3. Fusariosis sinusitis: This type of infection affects the paranasal sinuses and can cause chronic rhinosinusitis, meningitis, and ocular involvement.
4. Fusariosis pneumonia: This type of infection affects the lungs and can cause fever, cough, and difficulty breathing.
5. Fusariosis disseminated: This type of infection affects multiple organs and tissues, including the skin, bones, joints, lungs, and central nervous system.

The signs and symptoms of fusariosis can vary depending on the severity and location of the infection, but common symptoms include:

* Skin lesions such as ulcers, nodules, and plaques
* Joint pain and swelling
* Bone pain and limited mobility
* Fever
* Cough
* Difficulty breathing
* Headache
* Fatigue
* Weight loss

The diagnosis of fusariosis is based on a combination of clinical findings, laboratory tests, and imaging studies. Laboratory tests may include:

* Blood cultures: to isolate the fungus from the blood
* Skin or tissue biopsy: to confirm the presence of the fungus in the affected tissue
* Imaging studies such as X-rays, CT scans, or MRI scans: to evaluate the extent of the infection

Treatment of fusariosis is challenging and requires a multidisciplinary approach. The primary goal of treatment is to manage symptoms, prevent complications, and improve quality of life. Treatment options include:

* Antifungal medications: to target the fungus and prevent its growth
* Pain management: to control pain and discomfort
* Wound care: to promote healing of skin lesions and prevent further injury
* Physical therapy: to maintain joint mobility and strength
* Respiratory support: to manage respiratory symptoms
* Nutritional support: to ensure adequate nutrition and hydration

The prognosis for patients with fusariosis is generally poor, with high mortality rates reported in some cases. However, with early diagnosis, appropriate treatment, and close monitoring, some patients may experience improved symptoms and quality of life. It is important to note that the risk of recurrence is high in patients with fusariosis, and ongoing management and surveillance are often necessary to prevent further infections.

Prevention of fusariosis is challenging, but some measures can be taken to reduce the risk of infection. These include:

* Avoiding exposure to fungal spores
* Practicing good wound care and hygiene
* Avoiding immunosuppressive medications whenever possible
* Monitoring for signs of infection and seeking medical attention promptly if symptoms develop

Overall, fusariosis is a severe and potentially life-threatening infection that requires prompt diagnosis and appropriate treatment. With early intervention and ongoing management, some patients may experience improved outcomes and quality of life.

1. Infection: Bacterial or viral infections can develop after surgery, potentially leading to sepsis or organ failure.
2. Adhesions: Scar tissue can form during the healing process, which can cause bowel obstruction, chronic pain, or other complications.
3. Wound complications: Incisional hernias, wound dehiscence (separation of the wound edges), and wound infections can occur.
4. Respiratory problems: Pneumonia, respiratory failure, and atelectasis (collapsed lung) can develop after surgery, particularly in older adults or those with pre-existing respiratory conditions.
5. Cardiovascular complications: Myocardial infarction (heart attack), cardiac arrhythmias, and cardiac failure can occur after surgery, especially in high-risk patients.
6. Renal (kidney) problems: Acute kidney injury or chronic kidney disease can develop postoperatively, particularly in patients with pre-existing renal impairment.
7. Neurological complications: Stroke, seizures, and neuropraxia (nerve damage) can occur after surgery, especially in patients with pre-existing neurological conditions.
8. Pulmonary embolism: Blood clots can form in the legs or lungs after surgery, potentially causing pulmonary embolism.
9. Anesthesia-related complications: Respiratory and cardiac complications can occur during anesthesia, including respiratory and cardiac arrest.
10. delayed healing: Wound healing may be delayed or impaired after surgery, particularly in patients with pre-existing medical conditions.

It is important for patients to be aware of these potential complications and to discuss any concerns with their surgeon and healthcare team before undergoing surgery.

Some common types of vision disorders include:

1. Myopia (nearsightedness): A condition where close objects are seen clearly, but distant objects appear blurry.
2. Hyperopia (farsightedness): A condition where distant objects are seen clearly, but close objects appear blurry.
3. Astigmatism: A condition where the cornea or lens of the eye is irregularly shaped, causing blurred vision at all distances.
4. Presbyopia: A condition that occurs as people age, where the lens of the eye loses flexibility and makes it difficult to focus on close objects.
5. Amblyopia (lazy eye): A condition where one eye has reduced vision due to abnormal development or injury.
6. Strabismus (crossed eyes): A condition where the eyes are misaligned and point in different directions.
7. Color blindness: A condition where people have difficulty perceiving certain colors, usually red and green.
8. Retinal disorders: Conditions that affect the retina, such as age-related macular degeneration, diabetic retinopathy, or retinal detachment.
9. Glaucoma: A group of conditions that damage the optic nerve, often due to increased pressure in the eye.
10. Cataracts: A clouding of the lens in the eye that can cause blurred vision and sensitivity to light.

Vision disorders can be diagnosed through a comprehensive eye exam, which includes a visual acuity test, refraction test, and dilated eye exam. Treatment options for vision disorders depend on the specific condition and may include glasses or contact lenses, medication, surgery, or a combination of these.

There are two main types of galactosemia:

1. Classical galactosemia: This is the most severe form of the disorder, and it is characterized by a complete lack of the enzyme galactose-1-phosphate uridylyltransferase (GALT). Without GALT, galactose builds up in the blood and tissues, leading to serious health problems.
2. Dialectical galactosemia: This form of the disorder is less severe than classical galactosemia, and it is characterized by a partial deficiency of GALT. People with dialectical galactosemia may experience some symptoms, but they are typically milder than those experienced by people with classical galactosemia.

Symptoms of galactosemia can include:

* Diarrhea
* Vomiting
* Jaundice (yellowing of the skin and eyes)
* Fatigue
* Poor feeding in infants
* Developmental delays

If left untreated, galactosemia can lead to a range of complications, including:

* Liver disease
* Kidney disease
* Increased risk of infections
* Delayed growth and development

The diagnosis of galactosemia is typically made through a combination of physical examination, medical history, and laboratory tests. Treatment for the disorder typically involves a strict diet that limits or eliminates galactose-containing foods, such as milk and other dairy products. In some cases, medication may also be prescribed to help manage symptoms.

Overall, early diagnosis and treatment of galactosemia are important for preventing or minimizing the risk of complications associated with this condition.

The test works by shining a light into the eye and measuring the way the light is distorted as it passes through the cornea. This distortion is caused by the curvature of the cornea and by any imperfections or abnormalities in its surface. The resulting distortion is called a "wavefront aberration."

The CWA test produces a map of the wavefront aberrations in the eye, which can be used to identify specific conditions and to determine the appropriate treatment. The test is painless and takes only a few minutes to perform.

CWA is commonly used to diagnose and monitor a range of eye conditions, including:

1. Astigmatism: This is a condition in which the cornea is irregularly shaped, causing blurred vision at all distances.
2. Nearsightedness (myopia): This is a condition in which close objects are seen clearly, but distant objects appear blurry.
3. Farsightedness (hyperopia): This is a condition in which distant objects are seen clearly, but close objects appear blurry.
4. Keratoconus: This is a progressive thinning of the cornea that can cause distorted vision and increase the risk of complications such as corneal scarring or blindness.
5. Other conditions such as presbyopia (age-related loss of near vision), amblyopia (lazy eye), and ocular injuries.

Overall, CWA is a valuable diagnostic tool for assessing the quality of the cornea and for diagnosing and monitoring a range of eye conditions. It can help eye care professionals to identify the underlying causes of vision problems and to develop effective treatment plans to improve vision and prevent complications.

1) They share similarities with humans: Many animal species share similar biological and physiological characteristics with humans, making them useful for studying human diseases. For example, mice and rats are often used to study diseases such as diabetes, heart disease, and cancer because they have similar metabolic and cardiovascular systems to humans.

2) They can be genetically manipulated: Animal disease models can be genetically engineered to develop specific diseases or to model human genetic disorders. This allows researchers to study the progression of the disease and test potential treatments in a controlled environment.

3) They can be used to test drugs and therapies: Before new drugs or therapies are tested in humans, they are often first tested in animal models of disease. This allows researchers to assess the safety and efficacy of the treatment before moving on to human clinical trials.

4) They can provide insights into disease mechanisms: Studying disease models in animals can provide valuable insights into the underlying mechanisms of a particular disease. This information can then be used to develop new treatments or improve existing ones.

5) Reduces the need for human testing: Using animal disease models reduces the need for human testing, which can be time-consuming, expensive, and ethically challenging. However, it is important to note that animal models are not perfect substitutes for human subjects, and results obtained from animal studies may not always translate to humans.

6) They can be used to study infectious diseases: Animal disease models can be used to study infectious diseases such as HIV, TB, and malaria. These models allow researchers to understand how the disease is transmitted, how it progresses, and how it responds to treatment.

7) They can be used to study complex diseases: Animal disease models can be used to study complex diseases such as cancer, diabetes, and heart disease. These models allow researchers to understand the underlying mechanisms of the disease and test potential treatments.

8) They are cost-effective: Animal disease models are often less expensive than human clinical trials, making them a cost-effective way to conduct research.

9) They can be used to study drug delivery: Animal disease models can be used to study drug delivery and pharmacokinetics, which is important for developing new drugs and drug delivery systems.

10) They can be used to study aging: Animal disease models can be used to study the aging process and age-related diseases such as Alzheimer's and Parkinson's. This allows researchers to understand how aging contributes to disease and develop potential treatments.

There are several different types of glaucoma, including:

* Open-angle glaucoma: This is the most common form of glaucoma, and is caused by slowed drainage of fluid from the eye.
* Closed-angle glaucoma: This type of glaucoma is caused by a blockage in the drainage channels of the eye, leading to a sudden increase in pressure.
* Normal-tension glaucoma: This type of glaucoma is caused by damage to the optic nerve even though the pressure in the eye is within the normal range.
* Congenital glaucoma: This is a rare type of glaucoma that is present at birth, and is caused by a developmental defect in the eye's drainage system.

Symptoms of glaucoma can include:

* Blurred vision
* Loss of peripheral vision
* Eye pain or pressure
* Redness of the eye
* Seeing halos around lights

Glaucoma is typically diagnosed with a combination of visual acuity tests, dilated eye exams, and imaging tests such as ultrasound or MRI. Treatment for glaucoma usually involves medication to reduce pressure in the eye, but may also include surgery to improve drainage or laser therapy to prevent further damage to the optic nerve.

Early detection and treatment of glaucoma is important to prevent vision loss, so it is important to have regular eye exams, especially if you are at risk for the condition. Risk factors for glaucoma include:

* Age (over 60)
* Family history of glaucoma
* Diabetes
* High blood pressure
* African or Hispanic ancestry

Overall, glaucoma is a serious eye condition that can cause vision loss if left untreated. Early detection and treatment are key to preventing vision loss and maintaining good eye health.

There are several types of fungal eye infections, including:

1. Aspergillosis: This is a common type of fungal infection that affects the eye. It is caused by the fungus Aspergillus and can occur in people with weakened immune systems or pre-existing eye conditions.
2. Candidemia: This is another common type of fungal infection that affects the eye. It is caused by the fungus Candida and can occur in people with weakened immune systems or pre-existing eye conditions.
3. Cryptococcosis: This is a rare type of fungal infection that affects the eye. It is caused by the fungus Cryptococcus and can occur in people with weakened immune systems, such as those with HIV/AIDS.
4. Histoplasmosis: This is a rare type of fungal infection that affects the eye. It is caused by the fungus Histoplasma and can occur in people who have been exposed to the fungus in soil or bird droppings.
5. Blastomycosis: This is a rare type of fungal infection that affects the eye. It is caused by the fungus Blastomyces and can occur in people who have been exposed to the fungus in soil or water.

Fungal eye infections can cause a range of symptoms, including redness, discharge, pain, and vision loss. Treatment typically involves antifungal medication and may also include surgery to remove any infected tissue. In severe cases, fungal eye infections can lead to blindness if left untreated.

Prevention measures for fungal eye infections include good hygiene practices, such as washing hands regularly and avoiding close contact with people who have the infection. People with weakened immune systems should also avoid exposure to fungi by avoiding outdoor activities during peak fungal growth seasons and wearing protective clothing when working or playing in areas where fungi are likely to be present.

Overall, fungal eye infections are uncommon but can be serious conditions that require prompt medical attention. If you suspect you may have a fungal eye infection, it is important to seek medical care as soon as possible to receive proper diagnosis and treatment.

Example Sentences:

1. The patient was diagnosed with iris disease and was prescribed antibiotic eye drops to help clear up the infection.
2. The doctor suspected that the patient's blurred vision was caused by an iris disease, so he referred the patient to a specialist for further evaluation.
3. Although the symptoms of iris disease can be uncomfortable, most cases can be effectively treated with medication and proper care.

Ectopia Lentis can be classified into two main types:

1. Ectopia Lentis Syndrome: This is a more severe form of the disorder, where the lens is displaced from its normal position and may be attached to the iris or other structures in the eye. This type is often associated with other congenital anomalies such as cataracts, glaucoma, and microphthalmia.
2. Ectopia Lentis Isolated: This is a milder form of the disorder, where the lens is displaced but not attached to other structures in the eye.

The exact cause of Ectopia Lentis is unknown, but it is believed to be due to genetic mutations or environmental factors during fetal development. The symptoms of the condition can vary depending on the severity and location of the displacement, but may include:

* Blurred vision
* Double vision
* Squinting or crossing of the eyes
* Light sensitivity
* Eye pain or discomfort
* Reduced visual acuity

Diagnosis of Ectopia Lentis is typically made through a comprehensive eye exam, including a visual acuity test, refraction test, and retinoscopy. Imaging tests such as ultrasound or MRI may also be used to confirm the diagnosis and assess the severity of the condition.

Treatment for Ectopia Lentis depends on the severity of the condition and may include:

* Glasses or contact lenses to correct refractive errors
* Surgery to reposition the lens or remove a cataract
* Prism glasses or lenses to align the images seen by each eye
* In some cases, enucleation (removal) of the affected eye may be necessary if the condition is severe and causes significant vision loss.

It's important for individuals with Ectopia Lentis to receive regular follow-up care from an ophthalmologist to monitor the progression of the condition and adjust treatment as needed. With appropriate management, many individuals with Ectopia Lentis can achieve good visual acuity and a satisfactory quality of life.

Symptoms: blurred vision, halos around lights, redness and pain in the eye, nausea and vomiting, and sensitivity to light.

Diagnosis: a comprehensive eye exam, including measurements of intraocular pressure (IOP) and assessment of the angle of the eye.

Treatment: may include medication to reduce IOP, laser or surgical treatment to improve drainage, and in some cases, vitrectomy (removal of the vitreous gel).

Prognosis: with prompt and appropriate treatment, vision can be preserved. However, if left untreated, angle-closure glaucoma can lead to permanent vision loss.

Etiology: can be caused by a variety of factors, including age-related changes, cataract surgery, trauma, and inflammation.

Prevalence: is more common in certain populations, such as those of Asian descent, and in those with a family history of the condition.

Some common types of eye infections include:

1. Conjunctivitis - a highly contagious infection of the conjunctiva, which is the thin membrane that covers the white part of the eye and the inside of the eyelids. It can be caused by bacteria or virus and is commonly known as pink eye.
2. Keratitis - an inflammation of the cornea, which is the clear dome-shaped surface at the front of the eye. It can be caused by bacteria, virus or fungi.
3. Uveitis - an inflammation of the uvea, which is the layer of tissue between the sclera and retina. It can cause pain, sensitivity to light and blurred vision.
4. Endophthalmitis - a severe infection inside the eye that can cause damage to the lens, retina and other structures. It is usually caused by bacteria or fungi and can be a complication of cataract surgery or other eye procedures.
5. Dacryocystitis - an inflammation of the tear ducts and sac that can cause pain, redness and swelling in the eyelid. It is usually caused by bacteria.

Eye infections can be diagnosed through a comprehensive eye exam, which may include a visual acuity test, dilated eye exam, tonometry and imaging tests such as ultrasound or CT scans. Treatment depends on the type of infection and severity of the condition, and may involve antibiotic or antiviral medication, anti-inflammatory medication or surgery. It is important to seek medical attention if symptoms persist or worsen over time, as untreated eye infections can lead to complications such as vision loss, corneal scarring and even blindness.

The condition can affect people of all ages but is more common in older adults and those with a history of atopic dermatitis or other skin conditions. The exact cause of exfoliation syndrome is not known, but it is thought to be related to hormonal changes, allergies, and certain medications.

Symptoms of exfoliation syndrome include:

* Widespread redness and scaling of the skin
* Dryness and cracking of the skin
* Itching and burning sensations
* Thickening of the skin
* Crusting and flaking of the skin

If you suspect that you or someone else may have exfoliation syndrome, it is important to seek medical attention as soon as possible. A healthcare professional can diagnose the condition by examining the skin and performing tests to rule out other conditions.

Treatment for exfoliation syndrome typically involves topical medications such as corticosteroids, immunomodulators, and moisturizers. In severe cases, oral medications may be prescribed. It is important to follow the treatment plan carefully and avoid scratching or rubbing the skin, as this can exacerbate the condition.

In addition to medical treatment, there are several self-care measures that can help manage the symptoms of exfoliation syndrome. These include:

* Keeping the skin moisturized with fragrance-free lotions and creams
* Avoiding harsh soaps and cleansers
* Using cool compresses to reduce itching and inflammation
* Wearing loose, breathable clothing to avoid irritating the skin
* Avoiding exposure to extreme temperatures and humidity

While exfoliation syndrome can be a challenging condition to manage, with proper treatment and self-care, it is possible to improve the symptoms and quality of life.

Symptoms of vitreous detachment may include:

* Flashes of light
* Floaters (specks or cobwebs in vision)
* Blurred vision
* Sensitivity to light
* Eye pain or discomfort

If the vitreous detachment is severe, it can cause retinal tears or retinal detachment, which can lead to blindness. In some cases, surgery may be necessary to repair the damage and prevent vision loss.

The vitreous gel is a clear, jelly-like substance that fills the center of the eye between the lens and the retina. As we age, the vitreous gel can become more liquid and pull away from the retina, causing vitreous detachment. This condition is relatively common and usually occurs in people over the age of 40.

Vitreous detachment is diagnosed through a comprehensive eye exam, which includes a visual acuity test, dilated eye exam, and imaging tests such as ultrasound or OCT scans. Treatment options for vitreous detachment depend on the severity of the condition and may include:

* Watchful waiting: Monitoring the condition with regular eye exams to ensure that it does not progress.
* Laser surgery: Using a laser to seal retinal tears or holes that may have developed due to vitreous detachment.
* Vitrectomy: A surgical procedure to remove the vitreous gel and repair any retinal damage.

It's important to seek medical attention if you experience sudden changes in your vision, such as flashes of light or blurred vision, as these can be signs of a more serious condition that requires prompt treatment.

Examples:

1. Retinal coloboma: A condition where a hole or gap in the retina, the light-sensitive tissue at the back of the eye, can cause vision loss or blindness.
2. Cerebral coloboma: A condition where a part of the brain is missing or underdeveloped, which can result in intellectual disability, seizures, and other neurological symptoms.
3. Coloboma of the eye: A condition where the iris or optic nerve is not properly formed, leading to vision problems such as amblyopia (lazy eye) or strabismus (crossed eyes).

Note: Coloboma is a relatively rare condition and can be diagnosed through imaging tests such as ultrasound, CT scan, or MRI. Treatment options vary depending on the location and severity of the defect, and may include surgery, medication, or other interventions to manage associated symptoms.

There are several types of radiation injuries, including:

1. Acute radiation syndrome (ARS): This occurs when a person is exposed to a high dose of ionizing radiation over a short period of time. Symptoms can include nausea, vomiting, diarrhea, fatigue, and damage to the bone marrow, lungs, and gastrointestinal system.
2. Chronic radiation syndrome: This occurs when a person is exposed to low levels of ionizing radiation over a longer period of time. Symptoms can include fatigue, skin changes, and an increased risk of cancer.
3. Radiation burns: These are similar to thermal burns, but are caused by the heat generated by ionizing radiation. They can cause skin damage, blistering, and scarring.
4. Ocular radiation injury: This occurs when the eyes are exposed to high levels of ionizing radiation, leading to damage to the retina and other parts of the eye.
5. Radiation-induced cancer: Exposure to high levels of ionizing radiation can increase the risk of developing cancer, particularly leukemia and other types of cancer that affect the bone marrow.

Radiation injuries are diagnosed based on a combination of physical examination, medical imaging (such as X-rays or CT scans), and laboratory tests. Treatment depends on the type and severity of the injury, but may include supportive care, medication, and radiation therapy to prevent further damage.

Preventing radiation injuries is important, especially in situations where exposure to ionizing radiation is unavoidable, such as in medical imaging or nuclear accidents. This can be achieved through the use of protective shielding, personal protective equipment, and strict safety protocols.

The most common symptoms of amebiasis are:

1. Diarrhea
2. Abdominal pain
3. Fever
4. Blood in the stool
5. Rectal pain
6. Tenesmus (a feeling of needing to have a bowel movement even when the bowels are empty)
7. Weakness and fatigue
8. Loss of appetite
9. Nausea and vomiting
10. Constipation

The infection is usually caused by ingesting food or water contaminated with feces, or by direct contact with someone who has the infection.

The disease is more common in areas with poor sanitation and hygiene, and can be diagnosed through a combination of physical examination, medical history, and laboratory tests such as stool samples or blood tests.

Treatment typically involves antiparasitic medications such as metronidazole or tinidazole, and supportive care to manage symptoms such as hydration, pain management, and nutritional support. In severe cases, hospitalization may be necessary to monitor and treat complications such as perforation of the colon, peritonitis, or abscesses.

Prevention measures include proper hand washing, avoiding consumption of contaminated food or water, and good sanitation and hygiene practices. Vaccines are not available for amebiasis, but research is ongoing to develop one.

There are several different types of uveitis, including:

1. Anterior uveitis: This type affects the front part of the eye and is the most common form of uveitis. It is often caused by an infection or injury.
2. Posterior uveitis: This type affects the back part of the eye and can be caused by a systemic disease such as sarcoidosis or juvenile idiopathic arthritis.
3. Intermediate uveitis: This type affects the middle layer of the eye and is often caused by an autoimmune disorder.
4. Panuveitis: This type affects the entire uvea and can be caused by a systemic disease such as vasculitis or Behçet's disease.

Symptoms of uveitis may include:

* Eye pain
* Redness and swelling in the eye
* Blurred vision
* Sensitivity to light
* Floaters (specks or cobwebs in your vision)
* Flashes of light

If you experience any of these symptoms, it is important to see an eye doctor as soon as possible. Uveitis can be diagnosed with a comprehensive eye exam, which may include imaging tests such as ultrasound or MRI. Treatment for uveitis depends on the cause and severity of the condition, but may include medication to reduce inflammation, antibiotics for infections, or surgery to remove any diseased tissue.

Early diagnosis and treatment are important to prevent complications such as cataracts, glaucoma, and blindness. If you have uveitis, it is important to follow your doctor's recommendations for treatment and monitoring to protect your vision.

There are several types of dry eye syndromes, including:

1. Dry eye disease (DED): This is the most common type of dry eye syndrome and is characterized by a deficiency in the tear film that covers the surface of the eye. It can be caused by a variety of factors such as aging, hormonal changes, medications, and environmental conditions.
2. Meibomian gland dysfunction (MGD): This type of dry eye syndrome is caused by problems with the meibomian glands, which are located in the eyelids and produce the fatty layer of the tear film. MGD can be caused by inflammation, blockages, or other issues that prevent the glands from functioning properly.
3. Aqueous deficient dry eye (ADDE): This type of dry eye syndrome is caused by a lack of the aqueous layer of the tear film, which is produced by the lacrimal gland. It can be caused by surgical removal of the lacrimal gland, injury to the gland, or other conditions that affect its function.
4. Evaporative dry eye (EDE): This type of dry eye syndrome is caused by a problem with the meibomian glands and the lipid layer of the tear film. It can be caused by inflammation, blockages, or other issues that prevent the glands from functioning properly.
5. Contact lens-related dry eye (CLDE): This type of dry eye syndrome is caused by wearing contact lenses, which can disrupt the natural tear film and cause dryness and irritation.
6. Sjögren's syndrome: This is an autoimmune disorder that affects the glands that produce tears and saliva, leading to dry eye syndrome and other symptoms.
7. Medications: Certain medications, such as antihistamines, decongestants, and blood pressure medications, can reduce tear production and lead to dry eye syndrome.
8. Hormonal changes: Changes in hormone levels, such as during menopause or pregnancy, can lead to dry eye syndrome.
9. Environmental factors: Dry air, smoke, wind, and dry climates can all contribute to dry eye syndrome.
10. Nutritional deficiencies: A lack of omega-3 fatty acids in the diet has been linked to an increased risk of dry eye syndrome.

It is important to note that dry eye syndrome can be a complex condition and may involve multiple factors. A comprehensive diagnosis from an eye doctor or other healthcare professional is necessary to determine the underlying cause and develop an effective treatment plan.

The retina is a layer of cells that lines the inside of the eye and senses light to send visual signals to the brain. When the retina becomes detached, it can no longer function properly, leading to vision loss or distortion.

Retinal detachment can be caused by a variety of factors, including:

1. Age-related changes: As we age, the vitreous gel that fills the eye can become more liquid and pull away from the retina, causing a retinal detachment.
2. Injury or trauma: A blow to the head or a penetrating injury can cause a retinal detachment.
3. Medical conditions: Certain conditions, such as diabetes, high blood pressure, and sickle cell disease, can increase the risk of developing a retinal detachment.
4. Genetic factors: Some people may be more prone to developing a retinal detachment due to inherited genetic factors.

Symptoms of retinal detachment may include:

1. Flashes of light: People may see flashes of light in the peripheral vision.
2. Floaters: Specks or cobwebs may appear in the vision, particularly in the periphery.
3. Blurred vision: Blurred vision or distorted vision may occur as the retina becomes detached.
4. Loss of vision: In severe cases, a retinal detachment can cause a complete loss of vision in one eye.

If you experience any of these symptoms, it is important to seek medical attention immediately. A comprehensive eye exam can diagnose a retinal detachment and determine the appropriate treatment.

Treatment for retinal detachment typically involves surgery to reattach the retina to the underlying tissue. In some cases, laser surgery may be used to seal off any tears or holes in the retina that caused the detachment. In more severe cases, a scleral buckle or other device may be implanted to support the retina and prevent further detachment.

In addition to surgical treatment, there are some lifestyle changes you can make to help reduce your risk of developing a retinal detachment:

1. Quit smoking: Smoking has been linked to an increased risk of retinal detachment. Quitting smoking can help reduce this risk.
2. Maintain a healthy blood pressure: High blood pressure can increase the risk of retinal detachment. Monitoring and controlling your blood pressure can help reduce this risk.
3. Wear protective eyewear: If you participate in activities that could potentially cause eye injury, such as sports or working with hazardous materials, wearing protective eyewear can help reduce the risk of retinal detachment.
4. Get regular eye exams: Regular comprehensive eye exams can help detect any potential issues with the retina before they become serious problems.

Overall, a retinal detachment is a serious condition that requires prompt medical attention to prevent long-term vision loss. By understanding the causes and symptoms of retinal detachment, as well as making lifestyle changes to reduce your risk, you can help protect your vision and maintain good eye health.

There are several types of edema, including:

1. Pitting edema: This type of edema occurs when the fluid accumulates in the tissues and leaves a pit or depression when it is pressed. It is commonly seen in the skin of the lower legs and feet.
2. Non-pitting edema: This type of edema does not leave a pit or depression when pressed. It is often seen in the face, hands, and arms.
3. Cytedema: This type of edema is caused by an accumulation of fluid in the tissues of the limbs, particularly in the hands and feet.
4. Edema nervorum: This type of edema affects the nerves and can cause pain, numbness, and tingling in the affected area.
5. Lymphedema: This is a condition where the lymphatic system is unable to properly drain fluid from the body, leading to swelling in the arms or legs.

Edema can be diagnosed through physical examination, medical history, and diagnostic tests such as imaging studies and blood tests. Treatment options for edema depend on the underlying cause, but may include medications, lifestyle changes, and compression garments. In some cases, surgery or other interventions may be necessary to remove excess fluid or tissue.

There are many different types of uveal diseases, including:

1. Uveitis: This is inflammation of the uvea, which can be caused by a variety of factors such as infection, injury, or autoimmune disorders.
2. Iridocyclitis: This is inflammation of the iris and ciliary body.
3. Choroiditis: This is inflammation of the choroid layer of the uvea.
4. Retinal vein occlusion: This is a blockage of the veins that carry blood away from the retina, which can cause vision loss.
5. Macular edema: This is swelling of the macula, the part of the retina responsible for central vision.
6. Age-related macular degeneration (AMD): This is a condition that affects the macula and can cause vision loss over time.
7. Diabetic retinopathy: This is a complication of diabetes that can cause damage to the blood vessels in the retina and lead to vision loss.
8. Retinal detachment: This is a condition where the retina becomes separated from the underlying tissue, leading to vision loss.
9. Retinal vein thrombosis: This is a blockage of the veins that carry blood away from the retina, which can cause vision loss.
10. Uveal melanoma: This is a type of cancer that affects the uvea and can be potentially life-threatening.

These are just a few examples of uveal diseases, and there are many other conditions that can affect the uvea as well. Treatment options for uveal diseases vary depending on the specific condition and its cause, but may include medications, laser surgery, or other procedures to treat inflammation, reduce swelling, or remove tumors.

The symptoms of PHPV can vary depending on the severity of the condition and may include:

* Cloudy or opaque vision
* Blurred vision
* Sensitivity to light
* Lazy eye (amblyopia)
* Abnormal pupillary size or shape

If left untreated, PHPV can lead to complications such as cataracts, glaucoma, and retinal detachment, which can cause vision loss. Treatment options for PHPV may include:

* Vitrectomy, a surgical procedure to remove the abnormal cells in the vitreous humor
* Laser therapy to reduce scar tissue and improve vision
* Glasses or contact lenses to correct refractive errors
* Orthoptic exercises to strengthen the affected eye muscles

Early detection and treatment of PHPV are essential to prevent long-term visual impairment. A comprehensive ophthalmological evaluation, including a thorough examination of the retina and vitreous humor, is necessary for accurate diagnosis and appropriate management of the condition.

Aniseikonia is characterized by an abnormal expansion or contraction of the visual field, resulting in a distorted perception of objects and their size. The condition can affect both the central and peripheral vision, and can cause difficulties with reading, driving, and other everyday tasks that require accurate visual acuity.

Diagnosis of aniseikonia typically involves a comprehensive eye exam to assess the visual acuity and refractive error, as well as imaging tests such as MRI or CT scans to rule out any underlying brain abnormalities. Treatment options for aniseikonia depend on the underlying cause of the condition, and may include corrective glasses or contact lenses, prism lenses, or surgery to correct refractive errors or other eye problems. In some cases, aniseikonia may be a symptom of a more serious underlying condition that requires further evaluation and treatment.

Some common examples of intraoperative complications include:

1. Bleeding: Excessive bleeding during surgery can lead to hypovolemia (low blood volume), anemia (low red blood cell count), and even death.
2. Infection: Surgical wounds can become infected, leading to sepsis or bacteremia (bacterial infection of the bloodstream).
3. Nerve damage: Surgery can sometimes result in nerve damage, leading to numbness, weakness, or paralysis.
4. Organ injury: Injury to organs such as the liver, lung, or bowel can occur during surgery, leading to complications such as bleeding, infection, or organ failure.
5. Anesthesia-related complications: Problems with anesthesia can include respiratory or cardiac depression, allergic reactions, or awareness during anesthesia (a rare but potentially devastating complication).
6. Hypotension: Low blood pressure during surgery can lead to inadequate perfusion of vital organs and tissues, resulting in organ damage or death.
7. Thromboembolism: Blood clots can form during surgery and travel to other parts of the body, causing complications such as stroke, pulmonary embolism, or deep vein thrombosis.
8. Postoperative respiratory failure: Respiratory complications can occur after surgery, leading to respiratory failure, pneumonia, or acute respiratory distress syndrome (ARDS).
9. Wound dehiscence: The incision site can separate or come open after surgery, leading to infection, fluid accumulation, or hernia.
10. Seroma: A collection of serous fluid that can develop at the surgical site, which can become infected and cause complications.
11. Nerve damage: Injury to nerves during surgery can result in numbness, weakness, or paralysis, sometimes permanently.
12. Urinary retention or incontinence: Surgery can damage the bladder or urinary sphincter, leading to urinary retention or incontinence.
13. Hematoma: A collection of blood that can develop at the surgical site, which can become infected and cause complications.
14. Pneumonia: Inflammation of the lungs after surgery can be caused by bacteria, viruses, or fungi and can lead to serious complications.
15. Sepsis: A systemic inflammatory response to infection that can occur after surgery, leading to organ dysfunction and death if not treated promptly.

It is important to note that these are potential complications, and not all patients will experience them. Additionally, many of these complications are rare, and the vast majority of surgeries are successful with minimal or no complications. However, it is important for patients to be aware of the potential risks before undergoing surgery so they can make an informed decision about their care.

Corneal endothelial cell loss can occur due to various factors such as age-related decline, genetic disorders, inflammation, trauma, or surgery. The symptoms of corneal endothelial cell loss may include vision blurredness, glare, halos, and sensitivity to light.

There are several methods for evaluating corneal endothelial cell loss, including:

1. Clinical examination: An ophthalmologist can use a slit lamp to examine the cornea and assess the density of the endothelial cells.
2. Endothelial cell count: This is a laboratory test that measures the number of endothelial cells in a sample of corneal tissue.
3. Confocal microscopy: This is a non-invasive imaging technique that uses lasers to create high-resolution images of the cornea and can help to identify changes in the endothelium.
4. Corneal thickness measurement: This is a test that measures the thickness of the cornea, which can be affected by endothelial cell loss.

Treatment options for corneal endothelial cell loss depend on the underlying cause and severity of the condition. In some cases, medication or other conservative measures may be sufficient to manage the symptoms. However, in more severe cases, surgical intervention may be necessary to replace or support the damaged endothelial cells.

Overall, corneal endothelial cell loss is a significant condition that can impact vision and eye health. Early detection and appropriate management are essential to prevent long-term complications and maintain good visual acuity.

Examples:

* Pupillary anomalies: Abnormalities in the size, shape, or position of the pupil.
* Pupillary block: A condition where the pupil is unable to open properly due to a blockage or obstruction.
* Pupillary dilation: The widening of the pupil, which can be a sign of certain medical conditions.
* Pupillary constriction: The narrowing of the pupil, which can be a sign of other medical conditions.

Symptoms:

* Difficulty seeing or blurred vision
* Sensitivity to light
* Eye pain or discomfort
* Redness or swelling of the eye
* Difficulty moving the eyes

Diagnosis:

* Comprehensive eye exam
* Pupillary reactivity test: Measures how responsive the pupils are to light.
* Ophthalmoscopy: Examines the interior of the eye, including the retina and optic nerve.

Treatment:

* Glasses or contact lenses to correct refractive errors
* Medication to treat underlying conditions such as infection or inflammation
* Surgery to remove blockages or repair damaged tissue
* Pupillary dilators to widen the pupil and improve vision.

Anatomy35

Organisms20

Diseases39

Chemicals and Drugs56

Analytical, Diagnostic and Therapeutic Techniques and Equipment65

Psychiatry and Psychology6

Phenomena and Processes35

Disciplines and Occupations4

Technology, Industry, Agriculture10

Information Science3

Health Care9

The role of optical defocus in regulating refractive development in infant monkeys. (1/242)

The growing eye: an autofocus system that works on very poor images. (2/242)

Long-term changes in retinal contrast sensitivity in chicks from frosted occluders and drugs: relations to myopia? (3/242)

The response to prism deviations in human infants. (4/242)

Recent developments in clinical photography. (5/242)

Effect of adaptation to telescopic spectacles on the initial human horizontal vestibuloocular reflex. (6/242)

Clinical effect of low vision aids. (7/242)

Form-deprivation myopia in monkeys is a graded phenomenon. (8/242)

Lenses

Contact Lenses

Contact Lenses, Hydrophilic

Lenses, Intraocular

Lens Cortex, Crystalline

Lens Capsule, Crystalline

Lens Diseases

Lens Nucleus, Crystalline

Cataract

Crystallins

Contact Lenses, Extended-Wear

Lens Subluxation

Contact Lens Solutions

Lens Implantation, Intraocular

Presbyopia

Accommodation, Ocular

Refraction, Ocular

Eye Proteins

Posterior Capsule of the Lens

beta-Crystallins

Cataract Extraction

Aphakia

Eyeglasses

alpha-Crystallins

Eye

Lens Plant

Cornea

Anterior Capsule of the Lens

Myopia

Silicones

Phacoemulsification

delta-Crystallins

Epithelial Cells

Hyperopia

Refractive Errors

Optics and Photonics

Visual Acuity

Phakic Intraocular Lenses

Pseudophakia

Aquaporins

Aging

Aphakia, Postcataract

beta-Crystallin B Chain

Silicone Elastomers

Iris

Capsulorhexis

Keratitis

Prosthesis Fitting

Corneal Edema

Epithelium

Proto-Oncogene Proteins c-maf

Paired Box Transcription Factors

Anterior Eye Segment

Tears

Corneal Topography

Astigmatism

Cattle

Vitreous Body

alpha-Crystallin B Chain

Microphthalmos

Salamandridae

Connexins

Ciliary Body

beta-Crystallin A Chain

Biometry

Acanthamoeba Keratitis

Corneal Ulcer

Corneal Diseases

Chick Embryo

Fluorescent Antibody Technique, Indirect

Aldehyde Reductase

Rabbits

Organ Culture Techniques

Hydrogel

Photography

Cell Differentiation

Notophthalmus viridescens

Capsule Opacification

Acanthamoeba

Scattering, Radiation