Encyclopedia - Keratoconus

What causes keratoconus?
How is keratoconus treated?

Keratoconus, also called conical cornea, results in the cornea changing from dome-shaped to cone-shaped through the progressive thinning of the cornea. Because the cornea is the part of the eye that refracts most of the light entering, the change of its shape prevents incoming light from being focused properly, ultimately distorting vision (astigmatism). In addition, vision may be impaired as a result of swelling and scarring of tissue. Keratoconus is a slow-developing disorder that almost always affects both eyes, though each eye may be affected differently.

What causes keratoconus?

Most cases have no known or traceable cause, though some cases have traced causes to heredity, others to injury, and yet others to diseases or medical disorders such as Down's Syndrome, Ehlers-Danlos Syndrome, Marfan's Syndrome, and Addison's Disease. In some cases, keratoconus has been linked to excessive eye rubbing and long-term use of hard contact lenses.

Keratoconus usually appears in puberty (late teens or early 20s), and progresses over a 10- to 20-year span, although it sometimes halts progression during that time. Not all cases are the same. Some progress faster and with more severity.

How is keratoconus treated?

The earliest signs of keratoconus include blurred vision where things far away appear out of focus, objects appear tilted, and glare and light sensitivity increases. As keratoconus progresses and if scarring has occurred, patients may have moderate to severe vision distortion including double vision, cloudy lenses, seeing halos around lights, and sometimes, pain or discomfort.

Patients in the early stages of keratoconus can have their vision corrected with eyeglasses or contact lenses. As the astigmatism progresses and the cornea continues to thin and change shape, patients must rely on specially fitted, rigid gas permeable lenses to improve vision. Because changes continue, frequent fittings and follow-up care is essential for optimum visual acuity. In most cases, the cornea stabilizes over time.

Though rare, corneal transplantation is advised when patients are unable to tolerate contact lens wear or when adequate vision can no longer be maintained with the use of contact lenses. One of the most successful corneal transplants, keratoconus corneal transplantation generally helps 9 out of 10 patients. Despite the success of corneal transplants, however, patients often still require the uses of glasses or contact lenses to correct nearsightedness or farsightedness.