Corneal Transplantation

WHat is the Cornea?

The cornea is the clear outermost layer of the eye. The cornea is the “window” of the eye; if it is cloudy, misshapen, or swollen, vision will be impaired. In order to “clean” the window, sometimes we prescribe drops, special contact lenses, or even recommend replacing parts or all of the cornea.

What is a Corneal Transplant?

A corneal transplant is a type of eye surgery performed by a cornea fellowship-trained ophthalmologist. A donor cornea is obtained from an eye bank, specially prepared for the type of surgery planned for you, and replaces your original cornea. Sometimes the full thickness of the cornea is exchanged with your cornea (this is called a Penetrating Keratoplasty, or PKP). More often, a partial transplant is performed to replace just the diseased layer of tissue.

What are the different type of transplants?

The type of transplant you are offered by your corneal specialist depends on the type of corneal disease and the depth of involvement of disease.

If you just have diseased tissue on the front part of the cornea, sometimes your cornea specialist may attempt a procedure called a DALK (Deep Anterior Lamellar Keratoplasty) where just the front part of the cornea is removed, preserving the back side of your cornea. This procedure is technically challenging and can only be performed successfully approximately 50-75% of the time.

When you have disease on the back of the cornea, an Endothelial Keratoplasty (DMEK, DSAEK) can be performed to remove and replaced just the diseased layer of tissue.

DMEK versus DSAEK

DMEK (Descemet membrane endothelial keratoplasty) and DSAEK (Descemet Stripping Automated Endothelial Keratoplasty) are both surgeries to replace the back side of the cornea. While there are similar indications for both surgeries, DMEK surgery, which is thinner, is often only considered for straightforward cases, while a DSAEK, which is thicker, may be considered for both straightforward and complex cases. Randomized clinical control trials have found that DMEK offers approximately 1.5 lines of better vision compared to DSAEK; however, the procedure is more technically challenging and novel, with less known about long-term outcomes.

What are the risks of corneal transplants?

Corneal transplantation always carries a risk of graft rejection, when your body attacks the cornea as a foreign object. This may occur even many years after surgery. Unfortunately, with each “rejection” episode after a corneal transplant, there is an increased risk that the graft will fail, or start to become cloudy and swollen without the ability to maintain clarity. After a corneal transplant, your eye care provider will keep you on steroid drops to decrease the amount of inflammation in the eye and prevent the risk of rejection.

In addition to the risk of rejection and graft failure, any surgery carries a risk of infection, permanent damage to surrounding ocular structures, and blindness. Talk to your provider about whether the risks of surgery are outweighed by the benefits of surgery.