Corneal Transplants, DSAEK, DMEK

What is a corneal transplant?

Corneal transplant surgery (also called penetrating keratoplasty), involves a surgeon removing a window of cloudy tissue (or just the depleted endothelial cells with DSAEK) from the cornea and replacing it with donor tissue.

What is the cornea?

The cornea is the front clear part of the eye.

What are endothelial cells?

The cells that line the inside of the cornea are endothelial cells. These cells pump water out of the cornea. Without these cells the cornea would swell to five times its normal thickness. A loss of these cells can also create a clouding of the cornea. To remedy this reduction in endothelial cells and the resulting swelling and cloudiness often requires a corneal transplant.

What causes the loss of endothelial cells?

Endothelial cells can be lost due to factors including:
  • Aging
  • Inherited diseases (such as Fuchs’ dystrophy)
  • Ocular trauma
  • Previous intraocular surgery

When a large number of these cells are lost there can be two approaches; in mild cases the condition can be controlled with medical therapy, but more severe cases require a corneal transplant. Most patients who require this procedure have experienced significant endothelial cell loss.

Corneal Transplant Surgery

Conventional corneal transplant surgery has about a 90% success rate, rate of rejection about 8%. In this procedure, the window of cloudy tissue is removed from the patient’s central cornea and replaced with donor tissue. This new tissue is then held in place with many tiny stitches. To heal properly, the stitches must be in place a minimum of two months but are often left in permanently. They are removed over several visits to the surgeon’s office. The stitches may cause the patient some discomfort and often during this period vision is poor. Occasionally there can be problems with sutures that come loose or cause infections. Episodes of donor tissue rejection can often be controlled with steroid drops. Some patients may also find that their vision never returns to the level it was before the endothelial cell loss; this is primarily due to a warping or “irregular astigmatism” that remains on the corneal graft. Full visual recovery can take up to 18 months. Your doctor will discuss your visual rehabilitation with you.

What is DSAEK?

Descemets Stripping Automated Endothelial Keratoplasty (DSAEK) procedure is a partial-thickness corneal transplant that only replaces the endothelial layer of tissue along with a little corneal tissue for stability. A thin piece of donor tissue is inserted onto the back surface of the patient’s cornea. Surgery itself takes much less time with an experienced surgeon, involves a smaller surgical incision, requires no corneal stitches, heals faster and more reliably and patient’s vision will recover faster.

There are many advantages to DSAEK vs. Conventional Corneal Transplant Surgery

  1. The wound incision is smaller; closer in size and location to a cataract surgery incision.
  2. Smaller wound = more stable; less likely to break open.
  3. No stitches are placed in the cornea; resulting in significantly less astigmatism.
  4. Recovery in vision usually only takes about 4 months, but can further improve over time.
  5. Due to only a thin layer of the cornea being replaced,over 90% of the patients own cornea remains; meaning a reduced incidence of donor rejection.

Who is a candidate for DSAEK?

Only patients with endothelial cell problems are candidates for DSAEK. Patients that have corneal scarring or other cornea conditions will still require the full-thickness
procedure (conventional corneal transplant). A DSAEK operation can be repeated if the original procedure fails; however if the DSAEK fails one or more times a conventional corneal transplant may be necessary.


What is DMEK?

DMEK is a partial-thickness cornea transplant procedure that involves selective removal of the patient's Descemet membrane and endothelium, followed by transplantation of donor corneal endothelium and Descemet membrane without additional stromal tissue from the donor. DMEK is very similar to DSAEK, except that the donor tissue implanted does not include any stromal tissue. It is a pure replacement of endothelium. This tends to give better visual results and a quicker recovery; however, donor disc dislocations and failures are more common. You should discuss both options with your surgeon.