As described by the National Eye Institute at the National Institutes of Health, keratoconus is a progressive thinning of the cornea. It is the most common corneal dystrophy in the U.S., affecting one in every 2,000 Americans. It is most prevalent in teenagers and adults in their 20s.
Keratoconus causes the middle of the cornea to thin, bulge outward, and form a rounded cone shape. This abnormal curvature of the cornea can cause double or blurred vision, nearsightedness, astigmatism, and increased sensitivity to light.
The causes of keratoconus aren’t known, but research indicates it is most likely influenced by a combination of genetic susceptibility along with environmental and hormonal influences. About seven percent of people with the condition have a history of keratoconus in their family. Keratoconus is diagnosed with a slit-lamp exam. Your eye care professional will also measure the curvature of your cornea.
Keratoconus usually affects both eyes. At first, the condition is corrected with glasses or soft contact lenses. As the disease progresses, you may need specially fitted contact lenses to correct the distortion of the cornea and provide better vision.
In most cases, the cornea stabilizes after a few years without causing severe vision problems. A small number of people with keratoconus may develop severe corneal scarring or become unable to tolerate a contact lens. For these people, a corneal transplant may be necessary.
As of 2016, one FDA-approved option for treating keratoconus at UT Southwestern is called Corneal Cross-linking (CXL), an in-office procedure that helps strengthen the weakening middle layer of the cornea called the stroma. First, riboflavin eye drops are applied to the corneal surface of eye. Next, UV light is shone onto the cornea, which causes more cross-linking bonds to form between the collagen fibers of the corneal stroma. The riboflavin eye drops and UV light work together to make the collagen stronger, which, in turn, stops the cornea from progressively bulging outwards.
The goal of CXL is to stop the cornea from becoming thinner, weaker, and more irregular in shape. CXL may stop vision from getting worse, but it cannot make the cornea normal again.