What is the Corneal Endothelium and What is Its Function?
The cornea is the clear, outermost layer of the eye, and is considered to be the “window” of the eye because it controls and focuses the entry of light into the eye.In fact, the cornea contributes 65-75% of the eye’s focusing power. The corneal endothelium (see the micrograph to the right of the diagram) is the single layer of cells located at the back of the cornea; it forms a barrier between the cornea and the fluid aqueous humor. If you were to look at the endothelium face-on, it would appear like a field of fried eggs, with each egg closely abutting its neighbor. To understand the function of the endothelium, it is important to remember that the cornea does not contain blood vessels. In tissues with blood vessels, oxygen and nutrients in the blood are able to pass through the walls of the capillaries to “feed” the cells of the tissue. In the cornea, most of the oxygen comes from the air, passes into the tear film, and then into the cornea. The majority of the nutrients needed by th
