Keratoconus occurs when your cornea — the clear, round, "window" of tissue that allows light to enter the front of the eye — thins out, gradually producing a cone-shaped bulge in the front of your eye. A cone-shaped cornea causes blurred or distorted vision and may cause increased sensitivity to light and glare. Keratoconus usually affects both eyes and typically begins during adolescence and continues into middle age.
In more severe cases, the decrease in visual acuity may be much more rapid. Although rare, patients can experience sudden clouding of vision called "acute hydrops." This results from a sudden influx of fluid into the cornea. Pain, light sensitivity and tearing are also possible.
Unfortunately, we do not know what causes keratoconus. There is likely a genetic predisposition. Keratoconus may also be associated with other disorders such as eczema, Down’s Syndrome and Marfan’s Syndrome. It is related to chronic eye rubbing. Although the causes of keratoconus may not be known, treatments for it are available.
In the early stages of keratoconus, the vision problems caused by the distorted cornea can be corrected effectively with glasses or soft contact lenses. As keratoconus progresses, special rigid, gas permeable contact lenses may be necessary.
When keratoconus results in corneal scarring, extreme thinning of the cornea, or the inability to tolerate the contact lens options, corneal transplantation is an option. Another name for corneal transplantation is penetrating keratoplasty. Of all transplant surgery done today -- including lung, heart, and kidney -- corneal transplants are the most common and the most successful. In corneal transplant surgery, the damaged cornea is removed and a clear donor cornea is sewn into place. Visual recovery may take up to a year after transplantation, and eyeglasses or contact lenses are often still needed to correct vision.
Several clinical trials are currently investigating the safety and efficacy of a new treatment for keratoconus, called corneal cross-linking. After having riboflavin drops applied to the corneas, they are exposed to 30 minutes of ultraviolet A (UVA) light. The procedure hardens and stabilizes the corneas, with the goal of preventing further thinning or bulging. The treatment is still in its testing phase, and additional study is needed before it is widely available.