The cornea is the clear covering of the front of the eye which bends, or refracts, light rays as they enter the eye. For clear vision to occur, the cornea must have the correct shape and clarity to focus incoming light rays precisely on the retina at the back of the eye. When the cornea becomes cloudy or misshapen from injury, infection or disease, transplantation may be recommended to replace it.
Corneal transplants are usually performed with local anesthesia so there is no pain. During the procedure, the cornea is replaced with one from a human donor. The new cornea carries little risk of rejection and can last for many years.
DSEK is the latest technique in corneal transplantation. Short for Descemet-stripping automated endothelial keratoplasty, DSEK offers clear post-operative vision and short recovery time to patients in need of new corneas.
During the procedure, the surgeon makes a mark in the surface of the patient's cornea with a trephine (an instrument used to cut circular sections of tissue). That mark serves two purposes: it helps the surgeon determine what size the transplant should be, and it outlines the area of the patient's cornea that needs to be peeled away. Next, the surgeon scores the damaged section of the cornea and strips the membrane away from the eye. Then the donor cornea is folded into a "taco" shape and placed on the eye. A single stitch closes the incision.
Sometimes the new cornea unfolds on its own; other times, the surgeon unfolds it him/herself. When it is unfolded, a second stitch is made to close the wound and anchor the new cornea in place. The surgeon then injects an air bubble underneath the cornea, making sure it is centered on the eye, and dilates the pupil with eye drops.
An improperly curved cornea may be corrected surgically for patients whose curvature is too steep or flat to be treated with other methods, or when extensive damage has occurred due to disease, infection or surgery.
Corneal transplantation, also known as keratoplasty, may be performed in patients with:
Penetrating keratoplasty (PKP) involves replacing the entire thickness of the cornea with a donor graft. The new cornea is stitched into place, and stitches are usually removed after a year. It may take this long for vision to be restored to satisfactory levels as well, requiring many patients to wear glasses or contact lenses after this procedure.