cornea

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cornea:

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. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Cornea

 

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.

O. G. STROEVA

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

cornea

[′kȯr·nē·ə]
(anatomy)
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.

cornea

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 ?
"In India alone, there are over a million people suffering from the bilateral loss of vision due to corneal disorders, and at least a few folds more from unilateral corneal blindness.
When evaluating corneal apex clearance with RGP lenses designed for reshaping the cornea, as with ortho-k, clearance may be as low as 3-4[micro]m, which is impossible to assess using the conventional method of NaFl alone.
The current standard treatments for corneal defects include synthetic glues as well as surgery.
The risk factors [Table 1] for postoperative phacoemulsification corneal oedema include the following:
Keywords: Age-related changes, Central corneal thickness, Endothelial cell density.
Prof Dr Ibrar Hussain Chairman Ophthalmology Department gave a detailed presentation about the corneal bank, its functions and collection donor and how it will be run.
The patients underwent preoperative and postoperative examination including ophthalmologic examination, corneal topography using two different technologies, the GALILEI-Dual Scheimpflug Analyzer (Ziemer Group AG, Switzerland) and the Wavelight Allegro Topolyzer (Alcon Laboratories, Inc., Fort Worth, TX, USA), and ORA measurement.
Corneal transplantation is awide-spread surgical procedurewhere a damaged or diseasedcorneais replaced by donated corneal tissue.
Corneal dystrophies are a group of rare hereditary disorders identified by bilateral abnormal deposition of substances in the front transparent part of the eye called cornea.
Results: Out of 50 cases of corneal scrapings, 9 (18%) cases of bacterial pathogen were confirmed on Grams staining.
The Ophthalmology Department of KTH is becoming a leading department in KP in treating the corneal transplant patients according to the new standard guidelines.