THE CORNEA

The eye is enclosed by a tough white sac, the sclera. The cornea is the transparent window in this white sac which allows the objects you are looking at to be carried in the form of light waves into the interior of the eye.

The surface of the cornea is where light begins its journey into the eye. The cornea’s mission is to gather and focus visual images. Because it is out front, like the windshield of an automobile, it is subject to considerable abuse from the outside world.

The cornea is masterfully engineered so that only the most expensive manmade lenses can match its precision. The smoothness and shape of the cornea, as well as its transparency, is vitally important to the proper functioning of the eye. If either the surface smoothness or the clarity of the cornea suffers, vision will be disrupted.

CORNEAL LAYERS

Although appearing to be one clear membrane, the cornea is composed of five distinct layers of tissue, each with its own function.

• Epithelium is the thin outermost layer of fast-growing and easily-regenerated cells.
• Bowman’s layer consists of irregularly-arranged collagen fibers and protects the corneal stroma. It is 8 to 14 microns thick.
• Stroma, the transparent middle and thickest layer of the cornea is made up of regularly-arranged collagen fibers and keratocytes (specialized cells that secrete the collagen and proteoglycans needed to maintain the clarity and curvature of the cornea)
• Descemet’s membrane is a thin layer that serves as the modified basement membrane of the corneal endothelium.
• Endothelium is a single layer of cells responsible for maintaining proper fluid balance between the aqueous and corneal stromal compartments keeping the cornea transparent.