An endothelial keratoplasty (EK) is a partial-thickness corneal transplant that replaces the diseased innermost layer of the cornea. There are two types of EK that we perform: DSAEK and DMEK.
Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK)
DSAEK is a new technique that can help some patients who previously required a full thickness corneal transplant. Both the conventional corneal transplant technique and DSAEK require use of a donor cornea, but DSAEK replaces only the diseased posterior section of the cornea. This procedure, which requires minimal suturing, allows more rapid visual restoration, less discomfort, and a reduced risk of some sight-threatening complications.
The cornea is the clear window at the front of the eye that bends and helps focus light onto the back of the eye (the retina). In order for vision to be clear, the cornea must be clean and clear. Corneal disease can cause the cornea to become opaque or cloudy, preventing light from passing through clearly.
With a conventional corneal transplant, the full thickness of the cornea is completely removed, and a whole new donor cornea is sutured around the circumference of the cornea. These sutures can remain in the eye for over a year and can cause the cornea to take on an irregular shape during the healing process that is difficult to correct with glasses or contact lenses. This can result in less than optimum postoperative vision. DSAEK, on the other hand, involves removing only Descemet’s membrane and the damaged endothelial cells and leaves the surface of the cornea intact. The surgery is usually performed on an outpatient basis.
Descemet Membrane Endothelial Keratoplasty (DMEK)
DMEK is the newest technique that has been used to treat diseases of the innermost layer of the cornea. Similar to DSAEK corneal transplant, DMEK involves replacing the diseased posterior layer of the cornea (endothelium and Descemet’s membrane) with a healthy layer from a donor cornea. However, the DMEK tissue does not include any stromal tissue, therefore making the DMEK transplant approximately 10 times thinner compared to DSAEK.
The potential benefits of DMEK may include faster visual rehabilitation and higher visual acuity outcome compared to more traditional transplants. Common conditions that may benefit from DMEK are Fuchs corneal dystrophy and bullous keratopathy. The surgery is usually performed on an outpatient basis.
What to expect on surgery day
You will arrive at the surgery center about an hour prior to your procedure. Once you have been checked in you may be offered a sedative to help you relax. You will then be prepared for surgery. The area around your eyes will be cleaned and a sterile drape may be applied around your eye.
A small incision will be made to allow the surgeon to strip away the diseased Descemet’s membrane and damaged endothelial cells. Next, the bottom 10-20% of a donor cornea that has healthy endothelial cells attached to its Descemet’s membrane will be inserted through the same incision. After it is placed in position, an air bubble will be used to hold the transplanted tissue in place.
After your EK procedure
Immediately after the procedure, you will be taken into recovery where you will lie down for about an hour to let the air bubble continue to press against the tissue to secure it in place. Your eye will be patched before you leave. Antibiotic eye drops will be used for a week or so to help prevent infection, and a mild steroid eye drop will need to be used for a year or so to help prevent rejection.
You should be able to resume normal activities the day after your surgery. With conventional corneal transplantation, your vision typically does not improve for many months, while with EK, you may experience visual improvement within weeks. If you need transplants in both eyes, EK allows you to have the second transplant within months, versus a year or more if you were to have a conventional transplant.
In order to make your EK procedure a success, it is important that ALL scheduled appointments be kept and ALL medications are used as directed. Any pain, redness, or reduced vision should be reported immediately.
The decision to have EK is an important one that only you can make. The goal of any vision restoration procedure is to improve your vision. However, we cannot guarantee you will have the results you desire. Rejection could happen (although rarely) at any time in the future. However, if the transplanted tissue should be rejected, it is usually possible to have the procedure successfully repeated.