Keratoconus is a condition that affects the cornea, the transparent "window" over the eye. Normally, the cornea is round. As light hits the eye, the image is bent by the cornea and focused onto the retina, or light-sensitive membrane at the back of the eye. In keratoconus, the cornea thins and becomes cone-shaped. The steeper pitched cornea changes the way light is refracted as it comes into the eye. Images don't fall properly onto the retina, leading to changes in vision.

In the beginning stages, patients may notice a slight blurring or distortion of images. They may also notice a sensitivity to light, difficulties seeing clearly at night, eye strain, headaches and reading difficulties. The condition tends to progress slowly for 10 to 20 years and then often stabilizes. In severe cases, scars can form at the peak of the corneal cone and impair vision further.

The National Keratoconus Foundation estimates about one in 2,000 Americans have keratoconus. Symptoms most commonly appear in teens and young adults. About 13 percent of patients have a family history of the condition.

Treatment Options

Keratoconus patients with mild vision problems may use eyeglasses or soft contact lenses to improve symptoms. As the disease progresses and the cornea steepens, rigid gas permeable contacts may be needed. Eventually, the cornea can become so thinned and scarred a corneal transplant is needed. According to the Eye Bank Association of America, more than 33,670 corneal transplants were performed in the U.S. in 2006. Keratoconus is one of the main reasons for a transplant.

Researchers at Emory University in Atlanta are studying another treatment for keratoconus, called Corneal Collagen Cross-Linking. First, a thin layer of cells is removed from the top of the cornea. Then drops containing riboflavin are placed into the eye. The riboflavin saturates the cornea for 30 minutes. Then, the eye is exposed to ultraviolet A (UVA) light for 30 more minutes. The UVA light interacts with the riboflavin, causing the formation of chemical bonds (called cross-links) between the collagen molecules in the cornea. This causes the cornea to stiffen and makes it able to retain a rounder shape.

Doyle Stulting, M.D., Ph.D., Cornea Specialist with Emory Eye Center in Atlanta, says patients are given a topical anesthetic before the treatment, so there is no discomfort during the procedure. When the treatment is finished, a soft contact lens is placed in the eye to protect the cornea as it heals. The contact lens is removed after three to five days. As the cornea heals and stiffens, the curvature gradually improves. Stulting says it takes about a month to see any noticeable improvement. The beneficial effects last at least one year and perhaps even longer. In fact, a single treatment may stabilize the cornea and reverse some of the otherwise permanent changes in the integrity and curvature.

Clinical trials for the cross-linking study began in January. Stulting is hoping the treatment will be approved by the FDA in one to two years. For information on the trial, go to http://www.clinicaltrials.gov. Then type the trial identification number in the search box: NCT00567671. If you are interested in coming to Emory to take part in the study, call (404) 778-6155. Other study sites are located at:

Gordon Binder and Weiss Vision Institute, San Diego, CA

Center for Excellence in Eye Care, Miami, FL

Price Vision Group, Indianapolis, IN

Durrie Vision, PA, Overland Park, KS

Wilmer Eye Institute at Johns Hopkins, Baltimore, MD

Minnesota Eye Consultants, Bloomington, MN

Minnesota Eye Consultants, Minneapolis, MN

Cornea and Laser Eye Institute, Teaneck, NJ

TLC Laser Eye Center, Garden City, NY

Ophthalmic Consultants of Long Island, Lynbrook, NY

Edward Harkness Eye Institute, Columbia University Medical Center, New York, NY

Ophthalmic Consultants of Long Island, Rockville Centre, NY

For information on the clinical trial, go to http://www.clinicaltrials.gov. Then type the trial identification number in the search box: NCT00567671. If you are interested in coming to Emory to take part in the study, call (404) 778-6155.)

For general information on Keratoconus:

National Keratoconus Foundation

American Optometric Association

National Eye Institute