Keratoconus

Background: Keratoconus (KCN) is a progressive, non-inflammatory, bilateral (but usually asymmetrical) disease in which the cornea (clear front layer of the eye) becomes thin and protrudes. Keratoconus means "cone-shaped cornea." The abnormal shape causes distortion of vision.

Cause: The cause of KCN is unknown. Although KCN is not considered an inherited condition, the chance of a blood relative having KCN may be as high as one in ten. Vigorous eye rubbing may cause worsening of the condition. Patients with KCN are advised to avoid eye rubbing.

Frequency: In the US, reported prevalence in the general population varies (50-200 per 100,000), perhaps with differences in diagnostic criteria. It is commonly an isolated ocular condition but sometimes coexists with other ocular and systemic diseases. Particular risk factors include atopic history, especially ocular allergies, rigid contact lens (RGP CL) wear, and vigorous eye rubbing.

Symptoms: Blurring and distortion of vision are the earliest symptoms of KCN. Symptoms usually occur in the late teens and early twenties. The condition will often progress for ten to twenty years and then stabilizes.

A sudden decrease in vision may occur if the cornea swells after the elastic part of the cornea develops a small crack. The swelling may persist for weeks or months as the crack heals and is later replaced by scar tissue.

Treatment: Mild KCN may be successfully treated with glasses or contact lenses. When vision is no longer satisfactory with glasses or contacts, surgery may be recommended. A corneal transplant is often performed. Only 10-20% of patients with KCN eventually require a transplant. Other surgeries such as INTACS (plastic segments inserted in the cornea) may be helpful for some patients.