The cornea is the clear transparent dome in the front of the eye. In addition to allowing light to pass through the eye, the cornea does most of the bending (refracting) of light so that it can focus clearly on the retina.

Corneal edema (swelling), corneal dystrophies (inherited diseases), corneal scars, injuries, and infections can cause a normal, clear cornea to become cloudy, resulting in loss of vision in one or both eyes.

Some diseases such as keratoconus distort the shape of the cornea, so that the incoming light is not clearly focused on the retina. Even though the cornea appears clear in these diseases, the patient’s vision can still be very blurry.

Examination
A technician evaluates your visual acuity and checks your glasses prescription. Then the doctor examines the front part of the eye using a slit lamp bio-microscope, an instrument that provides a magnified view of the cornea.

In some cases other tests may be required. These include pachymetry, which measures the thickness of the cornea, or corneal topography, which creates a computerized contour map of the cornea.

Treatment
Some corneal diseases are easily treatable with new glasses or simply with drops. Many cases of keratoconus can be treated with contact lenses.

More severe corneal scars, advanced dystrophies, and advanced keratoconus are often treated with corneal transplant surgery.

Corneal Transplant
Corneal transplantation is a delicate but highly successful procedure. Under an operating microscope the doctor removes the diseased part of the cornea and replaces it with a donated healthy cornea. The donor cornea is secured into position with a number of very fine nylon sutures. The operation, which takes about an hour, is most often performed as an outpatient procedure and done with either local or general anesthesia.

Elliot M. Perlman, M.D. is one of the first corneal surgeons in New England to perform a new type of corneal transplant, called DSAEK (Descemet's Stripping Automated Endothelial Keratoplasty). In this procedure, only the innermost layers of the cornea are transplanted. DSAEK utilizes very few sutures and allows a more rapid recovery time than conventional corneal transplant.