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Eye Health and Keratoconus

We see through the cornea, which is the clear outer lens or "windshield" of the eye. Normally, the cornea has a dome shape, like a ball. Sometimes, however, the structure of the cornea is just not strong enough to hold this round shape and the cornea bulges outward like a cone. This condition is called keratoconus.

What Causes Keratoconus?

Tiny fibers of protein in the eye called collagen help hold the cornea in place and keep it from bulging. When these fibers become weak, they cannot hold the shape and the cornea becomes progressively more cone shaped.

Keratoconus is caused by a decrease in protective antioxidants in the cornea. The cornea cells produce damaging by-products, like exhaust from a car. Normally, antioxidants get rid of them and protect the collagen fibers. If antioxidants levels are low, the collagen weakens and the cornea bulges out.

Keratoconus appears to run in families. If you have it and have children, it’s a good idea to have their eyes checked for it starting at age 10. The condition progresses more rapidly in people with certain medical problems, including certain allergic conditions. It could be related to chronic eye rubbing.

Keratoconus usually starts in the teenage years. It can, though, begin in childhood or in people up to about age 30. It's possible it can occur in people 40 and older, but that is less common.

The changes in the shape of the cornea can happen quickly or may occur over several years. The changes can result in blurred vision, glare and halos at night, and the streaking of lights.

The changes can stop at any time, or they can continue for decades. There is no way to predict how it will progress. In most people who have keratoconus, both eyes are eventually affected, although not always to the same extent. It usually develops in one eye first and then later in the other eye.

With severe keratoconus, the stretched collagen fibers can lead to severe scarring.  If the back of the cornea tears, it can swell and take many months for the swelling to go away. This often causes a large corneal scar.

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