Akademik

Cornea

The clear front window of the eye. The cornea transmits and focuses light into the eye. The eye has a number of other components. These include the iris, pupil, lens, retina, macula, optic nerve and vitreous. The iris is the colored part of the eye that helps regulate the amount of light that enters the eye. The pupil is the dark aperture in the iris that determines how much light is let into the eye. The lens is the transparent structure inside the eye that focuses light rays onto the retina. The retina is the nerve layer that lines the back of the eye, senses light and creates impulses that travel through the optic nerve to the brain. The macula is a small area in the retina that contains special light-sensitive cells and allows us to see fine details clearly. The optic nerve is the nerve that connects the eye to the brain and carries the impulses formed by the retina to the visual cortex of the brain. The vitreous humor is a clear, jelly-like substance that fills the middle of the eye.

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The transparent tissue constituting the anterior sixth of the outer wall of the eye, with a 7.7-mm radius of curvature as contrasted with the 13.5 mm of the sclera; it consists of stratified squamous epithelium continuous with that of the conjunctiva, a substantia propria, substantially regularly arranged collagen imbedded in mucopolysaccharide, and an inner layer of endothelium. It is the chief refractory structure of the eye. [L. fem. of corneus, horny]

- conical c. SYN: keratoconus.

- c. farinata bilateral speckling of the posterior part of the corneal stroma. SYN: floury c..

- floury c. SYN: c. farinata.

- c. plana a congenital disorder in which the arc curvature of the c. is flatter than normal, leaving the eye hyperopic.

- c. urica bilateral deposition of crystalline deposits of urea and sodium urate within corneal stroma.

- c. verticillata congenital whorl-like opacities in the c.. SYN: Fleischer vortex.

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cor·nea 'kȯr-nē-ə n the transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior

cor·ne·al -əl adj

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the transparent circular part of the front of the eyeball. It refracts the light entering the eye onto the lens, which then focuses it onto the retina. The cornea contains no blood vessels and it is extremely sensitive to pain. The innermost layer (corneal endothelium) consists of a single layer of cells that cannot regenerate.

• corneal adj.

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cor·nea (korґne-ə) [L. corneus horny] [TA] the transparent structure forming the anterior part of the sclera of the eye. It consists of five layers: (1) the anterior corneal epithelium, continuous with that of the conjunctiva; (2) the anterior limiting layer (Bowman membrane); (3) the substantia propria, or stroma; (4) the posterior limiting layer (Descemet membrane); and (5) the endothelium of the anterior chamber. corneal adj

Medical dictionary. 2011.