QS Study

Structures and Function of Cornea

The cornea is the clear front surface of the eye. It is the transparent fibrous coat in the anterior one-sixth of the eyeball. It allows light to enter the eye for vision. It lies directly in front of the iris and pupil, and it allows light to enter the eye.

It is the outer, transparent structure at the front of the eye that covers the iris, pupil and anterior chamber; it is the eye’s primary light-focusing structure.

Structure: The cornea must remain transparent to refract light properly, and the presence of even the tiniest blood vessels can interfere with this process. It consists of five layers from outer to inner they are –

Stratified squamous epithelium: It is 5-6 cells deep. Continuous with that of the conjunctiva. It rests on a basement membrane, secreted by the basal cells. It is the cornea’s outermost region, comprising about 10 percent of the tissue’s thickness.

Bowman’s layer (anterior elastic lamina): It is the anterior condensation of lamina pnopria. It is composed of strong layered protein fibers called collagen. Once injured, Bowman’s layer can form a scar as it heals.

Substantia propria (stroma): It is composed of collagen fibers and forms 90% of corneal thickness.

Descemet’s membrane (Posterior elastic membrane): It is a strong, homogeneous membrane. It is composed of collagen fibers and is made by the endothelial cells that lie below it.

Endothelium: It is formed by a single layer of flattened endothelium which is continuous with that of the anterior surface of the iris.

cornea 1

Fig: Structures of Cornea

Function: Its main function is to refract, or bend, light.

  • It is the main refractive media of the eye.
  • It protects the internal structures of the eye.
  • It gives the eyeball a proper shape.
  • It is responsible for focusing most of the light that enters the eye.
  • It also serves as a filter, screening out some of the most damaging ultraviolet (UV) wavelengths in sunlight.
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