Keratoconus

WHAT IS KERATOCONUS?

Keratoconus is a thinning condition of the cornea. It is found in one out of approximately 1,800 patients and often has a genetic predisposition. Usually beginning in adolescence, keratoconus worsens until about age 30 or 40 and then stabilizes. The thinning causes the cornea to bow outward like a cone, rather than have a normal spherical shape. In the early stages, a person may be only diagnosed with astigmatism unless special testing (corneal topography) is done. If the cone is small, glasses can often correct the astigmatism. Over time, however, the disorder can progress and lead to further thinning and steepening of the cone. Rigid gas permeable contact lenses are usually employed at this stage to allow the vision to be corrected. If the keratoconus progresses further with decreasing vision and contact lens intolerance, the next step would traditionally be corneal transplant surgery. About 10% of all keratoconus patients progress to the point where surgery is needed to rehabilitate vision.

HOW IS KERATOCONUS TREATED?

There are two methods of treatment for keratoconus and they are corneal transplantation or Intacs™.  If a corneal transplant is required to correct keratoconus, the surgery is relatively complex. The surgery is done in a hospital or surgery center setting, using an injection around the eye for anesthesia. A small button of the patient¹s cornea is removed using a calibrated round instrument. A new cornea is obtained from a screened donor, sized to match the removed tissue, and sewn into place using sutures that are thinner than a human hair. The vision returns slowly over the next year, as the surgeon adjusts the sutures to minimize any astigmatism caused by the sutures. The patient needs to use drops in the immediate postoperative period to prevent infection, then for the rest of his or her life to prevent rejection of the donor tissue. The chance of rejection is not as great as with most transplant procedures because the cornea does not have a blood supply, but the drops are needed to prevent such an occurrence. The vision can be quite good after the lengthy healing process is complete.

Intacs™ micro-thin corneal implants are an important alternative to corneal transplantation for keratoconus.. Dr. Talamo has been on the forefront of Intacs™ use and is able to offer this alternative to some carefully screened patients.  When used for keratoconus, one or two Intacs™ are used to flatten the corneal cone. The area of the cone can be quite thin in keratoconus, but the Intacs™ are placed outside the cone, where the cornea is thicker. The difference in the steepness of the cone can be seen in the topography maps shown below. Prior to implantation of the Intacs™, the cone can be seen as an off-center red area. After the Intacs™ have flattened the cone, the astigmatism is seen as a smaller, more centered spot on the topography map (see figure 1). Healing time is gradual, often taking three months to obtain the best vision. During this time, the vision improves gradually.