The eye maintains a circular shape so that it can properly focus images on the retina at the back of the eye, in turn creating good vision. If the outer portion of the eye, called the cornea, is diseased, misshaped or damaged, the eye can no longer focus properly, and poor vision can result. In severe cases of corneal damage, a corneal transplant can be used to remove and replace damaged tissue.
Corneal transplant is a surgical procedure to remove part of the existing corneal surface and replace it with new corneal tissue. The new tissue is typically donor tissue from a healthy cornea.
Keratoconus and Corneal Transplants
Keratoconus is one of the most common reasons patients receive corneal transplants. A corneal transplant may be warranted in advanced cases of keratoconus, when the corneal tissue becomes too thin or vision loss is too severe. Approximately 15% to 20% of keratoconus patients ultimately require the surgery. Since keratoconus is characterized by progressive loss of vision in both eyes, the transplants are performed on both eyes.
Types of Corneal Transplants
Corneal transplant surgery can vary depending on the amount of corneal tissue removed.
If the full thickness of the cornea is removed and replaced, this is referred to as a corneal transplant, penetrating keratoplasty or corneal graft. During this procedure, after the full depth of the corneal tissue is removed, a piece of donor cornea is precisely cut to put in place of the removed tissue. The donor tissue is then stitched in place.
The other two most common types of corneal transplants remove and replace only the rear layers or front layers of corneal tissue. During endothelial keratoplasty (EK), diseased tissue from the rear endothelium and Descemet’s membrane is removed and replaced. When a thicker piece of tissue is removed and replaced, the procedure is referred to as DSEK (Descemet’s stripping EK), while for thinner layers, the procedure is known as DMEK (Descemet’s membrane EK). DMEK, because of the very thin and fragile layer of tissue being removed, is a much more difficult procedure. Anterior lamellar keratoplasty (ALK) is performed when anterior layers of the cornea are removed and replaced. Again, two types of procedures can be performed, depending on the severity of the patient’s condition and location of the damaged corneal tissue. DALK (Deep ALK) is used when thicker tissue is removed and replaced, while for the thinner, most anterior part of the corneal tissue, SALK (Superficial ALK) is used.
Other Reasons for Corneal Transplants
Corneal transplants can be performed to restore vision in patients facing a variety of situations, such as when the cornea is damaged or has been torn, and conditions, such as Fuchs’ dystrophy. Eye infection and complications from a previous eye surgery can lead to vision loss that can be corrected with a corneal transplant.
Dr. Boxer Wachler can provide a complete examination of your eyes and cornea and select the best type of corneal surgery for your condition and level of vision loss. He is a leader and pioneer in corneal surgery and has specialty fellowship training in this area of eye care.