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What is the function of the cornea?

Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

Because the cornea is as smooth and clear as glass but strong and durable, it helps the eye in two ways:

It helps to shield the rest of the eye from germs, dust, and other harmful matter. The cornea shares this protective task with the eyelids, the eye socket, tears, and the sclera (or white part of the eye). The cornea acts as the eye's outermost lens. It functions like a window that controls and focuses the entry of light into the eye. The cornea contributes between 65-75 percent of the eye's total focusing power.

When light strikes the cornea, the cornea bends-or refracts-the light onto the lens. The lens further refocuses that light onto the retina, a layer of light-sensing cells that lines the back of the eye and starts translating light into vision. For you to see clearly, the cornea and the lens must focus light rays to fall precisely on the retina. The retina converts the light rays into impulses that are sent through the optic nerve to the brain, which interprets them as images.

The refractive process is similar to the way a camera takes a picture. The cornea and lens in the eye act as the camera lens. The retina is similar to the film. If the image is not focused properly, the film (or retina) receives a blurry image.

The cornea also serves as a filter, screening out some of the most damaging ultraviolet (UV) wavelengths in sunlight. Without this protection, the lens and the retina would be highly susceptible to injury from UV radiation.

This answer is based on source information from the National Institute of Diabetes and Digestive and Kidney Diseases.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.