As the cornea steepens and thins, the patient experiences a decrease in vision which can be mild or severe depending on the amount of corneal tissue affected. Keratoconus rarely develops after age 30 years. The disease process is active for about five to 10 years, then it may be stable for many years. During the active stage, change may be rapid. Contact lenses provide a uniform refracting surface and therefore improve vision.
Contact lenses can improve vision, but they can also scar the cornea.
Patients should be informed upon diagnosis that they will likely require contact lenses eventually. Although most patients can continue to read and drive, some feel quality of life is adversely affected. Patients need to know that eye examinations will be required annually or more frequently to monitor progression. The proposed etiology of keratoconus includes biochemical and physical corneal tissue changes, but no one theory fully explains the clinical findings and associated ocular and non-ocular disorders. It is possible that keratoconus is an end result or final common pathway of many different clinical conditions.