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)
Stratified squamous epithelium that covers the outer surface of the CORNEA. It is smooth and contains many free nerve endings.
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)
Injury to any part of the eye by extreme heat, chemical agents, or ultraviolet radiation.
New blood vessels originating from the corneal veins and extending from the limbus into the adjacent CORNEAL STROMA. Neovascularization in the superficial and/or deep corneal stroma is a sequel to numerous inflammatory diseases of the ocular anterior segment, such as TRACHOMA, viral interstitial KERATITIS, microbial KERATOCONJUNCTIVITIS, and the immune response elicited by CORNEAL TRANSPLANTATION.
Centers for storing various parts of the eye for future use.
An excessive amount of fluid in the cornea due to damage of the epithelium or endothelium causing decreased visual acuity.
A layer of the cornea. It is the basal lamina of the CORNEAL ENDOTHELIUM (from which it is secreted) separating it from the CORNEAL STROMA. It is a homogeneous structure composed of fine collagenous filaments, and slowly increases in thickness with age.
Fibroblasts which occur in the CORNEAL STROMA.
A sensory branch of the trigeminal (5th cranial) nerve. The ophthalmic nerve carries general afferents from the superficial division of the face including the eyeball, conjunctiva, upper eyelid, upper nose, nasal mucosa, and scalp.
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.
A superficial, epithelial Herpesvirus hominis infection of the cornea, characterized by the presence of small vesicles which may break down and coalesce to form dendritic ulcers (KERATITIS, DENDRITIC). (Dictionary of Visual Science, 3d ed)
An annular transitional zone, approximately 1 mm wide, between the cornea and the bulbar conjunctiva and sclera. It is highly vascular and is involved in the metabolism of the cornea. It is ophthalmologically significant in that it appears on the outer surface of the eyeball as a slight furrow, marking the line between the clear cornea and the sclera. (Dictionary of Visual Science, 3d ed)
A sulfated mucopolysaccharide initially isolated from bovine cornea. At least two types are known. Type I, found mostly in the cornea, contains D-galactose and D-glucosamine-6-O-sulfate as the repeating unit; type II, found in skeletal tissues, contains D-galactose and D-galactosamine-6-O-sulfate as the repeating unit.
Gas lasers with excited dimers (i.e., excimers) as the active medium. The most commonly used are rare gas monohalides (e.g., argon fluoride, xenon chloride). Their principal emission wavelengths are in the ultraviolet range and depend on the monohalide used (e.g., 193 nm for ArF, 308 nm for Xe Cl). These lasers are operated in pulsed and Q-switched modes and used in photoablative decomposition involving actual removal of tissue. (UMDNS, 2005)
The mucous membrane that covers the posterior surface of the eyelids and the anterior pericorneal surface of the eyeball.
A type of refractive surgery of the CORNEA to correct MYOPIA and ASTIGMATISM. An EXCIMER LASER is used directly on the surface of the EYE to remove some of the CORNEAL EPITHELIUM thus reshaping the anterior curvature of the cornea.
Corneal Dystrophies, Hereditary
Sterile solutions that are intended for instillation into the eye. It does not include solutions for cleaning eyeglasses or CONTACT LENS SOLUTIONS.
Damage or trauma inflicted to the eye by external means. The concept includes both surface injuries and intraocular injuries.
Fluorescent Antibody Technique, Indirect
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)
Fuchs' Endothelial Dystrophy
The fluid secreted by the lacrimal glands. This fluid moistens the CONJUNCTIVA and CORNEA.
Organ Culture Techniques
Devices intended to replace non-functioning organs. They may be temporary or permanent. Since they are intended always to function as the natural organs they are replacing, they should be differentiated from PROSTHESES AND IMPLANTS and specific types of prostheses which, though also replacements for body parts, are frequently cosmetic (EYE, ARTIFICIAL) as well as functional (ARTIFICIAL LIMBS).
The application of drug preparations to the surfaces of the body, especially the skin (ADMINISTRATION, CUTANEOUS) or mucous membranes. This method of treatment is used to avoid systemic side effects when high doses are required at a localized area or as an alternative systemic administration route, to avoid hepatic processing for example.
A layer of acellular matrix that lies beneath the CORNEAL EPITHELIUM and above the CORNEAL STROMA. It consists of randomly arranged COLLAGEN fibers in a condensed bed of intercellular substance. It provides stability and strength to the cornea.
Keratomileusis, Laser In Situ
A surgical procedure to correct MYOPIA by CORNEAL STROMA subtraction. It involves the use of a microkeratome to make a lamellar dissection of the CORNEA creating a flap with intact CORNEAL EPITHELIUM. After the flap is lifted, the underlying midstroma is reshaped with an EXCIMER LASER and the flap is returned to its original position.
Eye Infections, Fungal
Infection by a variety of fungi, usually through four possible mechanisms: superficial infection producing conjunctivitis, keratitis, or lacrimal obstruction; extension of infection from neighboring structures - skin, paranasal sinuses, nasopharynx; direct introduction during surgery or accidental penetrating trauma; or via the blood or lymphatic routes in patients with underlying mycoses.
A form of herpetic keratitis characterized by the formation of small vesicles which break down and coalesce to form recurring dendritic ulcers, characteristically irregular, linear, branching, and ending in knoblike extremities. (Dictionary of Visual Science, 3d ed)
A type I keratin that is found associated with the KERATIN-3 in the CORNEA and is regarded as a marker for corneal-type epithelial differentiation. Mutations in the gene for keratin-12 have been associated with MEESMANN CORNEAL EPITHELIAL DYSTROPHY.
Anterior Eye Segment
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)
A puncture or hole through the CORNEAL STROMA resulting from various diseases or trauma.
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)
Descemet Stripping Endothelial Keratoplasty
A surgical procedure or KERATOPLASTY involving selective stripping and replacement of diseased host DESCEMET MEMBRANE and CORNEAL ENDOTHELIUM with a suitable and healthy donor posterior lamella. The advantage to this procedure is that the normal corneal surface of the recipient is retained, thereby avoiding corneal surface incisions and sutures.
The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. (Cline et al., Dictionary of Visual Science, 4th ed, p109)
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.
Filarial infection of the eyes transmitted from person to person by bites of Onchocerca volvulus-infected black flies. The microfilariae of Onchocerca are thus deposited beneath the skin. They migrate through various tissues including the eye. Those persons infected have impaired vision and up to 20% are blind. The incidence of eye lesions has been reported to be as high as 30% in Central America and parts of Africa.
Contact Lenses, Hydrophilic
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.
A family of structurally related collagens that form the characteristic collagen fibril bundles seen in CONNECTIVE TISSUE.
Diseases affecting the eye.
Each of the upper and lower folds of SKIN which cover the EYE when closed.
Refraction of LIGHT effected by the media of the EYE.
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.