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see eyeeye,
organ of vision and light perception. In humans the eye is of the camera type, with an iris diaphragm and variable focusing, or accommodation. Other types of eye are the simple eye, found in many invertebrates, and the compound eye, found in insects and many other
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The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the anterior transparent part of the outer tunic of the eye that is part of the eye’s light-refracting apparatus and protects the eye from injury and dust.

There are five layers in the cornea: the anterior epithelium, the anterior limiting membrane (Bowman’s membrane), the substantia propria (connective-tissue stroma), the posterior, or Descemet’s, membrane, and the endothelium of the anterior chamber. Corneal epithelium is multilayered—in man it is composed of eight to ten layers with a total thickness reaching 50 micrometers. It is lined with Bowman’s membrane, which is an acellular part of the postepithelial stroma consisting of a network of collagenous fibers that run in various directions parallel to the surface of the cornea.

A membrane without a distinct boundary becomes the substantia propria of the cornea. In man the substantia propria occupies as much as 90 percent of the entire thickness of the cornea. It is solidly packed with collagenous fibers that are produced by fibroblasts; the intercellular matter of this layer contains mucopolysaccharides, chondroitin sulfate, chondroitin, and keratosulfate. The transparency of the cornea depends on the degree of dehydration and orderliness of the molecules of the acellular portion of the cornea’s basic matter.

Descemet’s membrane lines the basic matter of the cornea and is tough and elastic; its posterior surface is covered by the single-layered endothelium of the anterior chamber of the eye.

There are no blood vessels in corneal tissues. In man the cornea is innervated by 70–80 radial nerve trunks that originate in the optical branch of the fifth pair of cranial nerves; the branching of the trunks penetrates the entire thickness of the cornea, except Descemet’s membrane and the endothelium.

The most common diseases of the cornea include traumas, blennorrhea, keratitis, and staphyloma.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


The transparent anterior portion of the outer coat of the vertebrate eye covering the iris and the pupil.
(invertebrate zoology)
The outer transparent portion of each ommatidium of a compound eye.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


the convex transparent membrane that forms the anterior covering of the eyeball and is continuous with the sclera
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
"Last year, AIIMS retrieved about 2,234 cornea tissues which is the highest number till date in the past 50 years.
Rehman Malik about the Sight Foundation donation of eyes' cornea to Pakistani corneal blinded people.
The delegation briefed Senator Malik about the Sight Foundation donation of eyes' cornea to Pakistani corneal blinded people.
The Sri Lankan delegation thanked the prime minister for receiving them and said that the gift of corneas from the people of Sri Lanka would help in strengthening the bonds of friendship between the two nations.
They were able to enjoy normal life after a simple donation of cornea from dying men and women.
"But eye transplants really can transform people's lives and I'd encourage everyone to think about donating their corneas."
Of these, the sight of 200,000 people can be restored through Cornea transplants.
In Forth Valley over the past year, corneas were retrieved from around 15 patients.
A HUDDERSFIELD toddler is at the forefront of a campaign encouraging people to become cornea donors when they die after it emerged that eye bank stocks are running low.
Professor Connon emphasised that further testing of the artificial corneas needs to be completed and it would be several years before they can be used for corneal transplants.
The method consists of mixing stem cells from a healthy donor cornea with a gel derived from seaweed and collagen.
Yet there is a significant shortage of corneas available to transplant, with 10 million people worldwide requiring surgery to prevent corneal blindness as a result of diseases such as trachoma, an infectious eye disorder.