The Function of the Cornea

Text to Speech

The cornea is often described as being as smooth and clear as glass, but it is strong and durable also and helps the eye in two ways:

• It shields the rest of the eye from dust, germs and other harmful foreign matter. But the cornea shares this protective role with the eye socket, tears, eyelids, and the sclera or white part of the eye.
• It is the outermost lens of the eye, controlling and focusing incoming light. Actually, it is responsible for between 65 and 75 percent of the eye’s total focusing power.

When light strikes the cornea, it refracts it onto the lens. The lens adjusts the focus of light further onto the retina, a layer of light-sensing cells lining the back of the eye that converts the light into vision. To be able to see clearly, light rays must be focused by the cornea and lens to fall precisely on the retina. The retina then converts the rays into impulses sent through the optic nerve to the brain, which interprets them as images.

The process of light refraction can be likened to the way a camera takes a picture. The cornea and lens in the eye act in much the same way as a camera lens and the retina is similar to the film. If the image doesn’t focus correctly, a blurred image results.

The cornea’s protective role also serves as a filter, and blocks out some of the damaging ultraviolet wavelengths contained in sunlight. The lens and retina would be very susceptible to serious injury from UV radiation without this protection

---

Related Articles:

What is 20/20 Vision?

Eyes and Nutrition

Eye Coordination