When you have keratoconus your cornea gradually (over many years) begins to bulge outward, becoming cone-shaped. As it stretches, it weakens, like a weak spot in a tire. The irregular surface distorts the cornea’s focusing ability and results in blurred vision.
The degenerative process that leads to keratoconus usually begins in the early to mid-teenage years. It often slows down or stops between the ages of 25 to 40. Both eyes are usually affected, though the severity may be different in each eye. Keratoconus occurs in both sexes and all races. It is an inherited condition that sometimes occurs as part of other hereditary conditions. As long as visual problems are slight, they can be managed by changing the prescription of your eyeglasses. For a while, glasses may fully correct vision to 20/20. When, eventually, an eye can no longer be adequately corrected with glasses, a contact lens may provide surprisingly good vision; the difference is that a contact lens, which sits directly on the cornea, becomes a new “corneal” surface that is optically smooth. For some patients, contact lenses continue to work well for a lifetime, although they typically require many changes of fit and prescription over the years.
If the keratoconus continues to progress, the time may come when you can no longer wear contact lenses, either for reasons of comfort or because the cornea has become so distorted that the lens will not stay in place. At that time, a corneal transplant may be necessary. In this surgical procedure, the cone-shaped cornea is replaced with a normal donor cornea. Corneal transplants for keratoconus are highly successful (over 90%). Even after a successful transplant, however, you may still need to wear eyeglasses or contact lenses to obtain good vision.