What Is DSAEK/DMEK (Partial Thickness Corneal Transplant) Surgery?
The cornea is the clear dome at the very front part of the eye and is composed of five main layers. The endothelium is a single layer of cells coating the inside portion of the cornea. While the endothelium has many functions, one of its most important functions is to serve as a layer of vacuum pumps in order to pump fluid out of the cornea and keep it crystal clear. If the endothelium malfunctions, excess fluid can build up in the middle layers of the cornea and cause swelling of the cornea (corneal edema), leading to decreased vision. Patients report this blurry vision as “looking through a foggy shower door”. Some patients (such as those with Fuchs endothelial dystrophy) report this foggy vision is worst immediately after waking up in the morning and gets slightly better as the day goes on. Other patients with corneal edema due to other causes report blurry vision that is constantly poor throughout the day.
Descemet’s stripping automated endothelial keratoplasty (DSAEK) and Descemet’s membrane endothelial keratoplasty (DMEK) are partial thickness corneal transplants performed to replace the endothelium (the innermost portion of the cornea). DMEK is very similar to DSAEK, with the primary difference being that the donor tissue implanted does not include any stromal tissue, but is instead a pure replacement of endothelium. A DMEK graft, therefore, is much thinner than a DSAEK graft.
Both of these procedures are in contrast to replacing the full thickness of the cornea, as is the case with standard corneal transplants, and have the following advantages:
- Decreased risk of tissue rejection
- Quicker visual recovery
- Fewer activity restrictions
- Potential for better vision as compared to full-thickness corneal transplant surgery
Who’s A Good Candidate for a DSAEK or DMEK Surgery?
DSAEK and DMEK are best suited for patients with conditions related to the endothelial cells, which include:
- Fuchs’ endothelial dystrophy
- Iridocorneal endothelial syndrome
- Bullous keratopathy
- Congenital hereditary endothelial dystrophy
- Corneal edema due to complications from other types of eye surgery
A full-thickness corneal transplant will still be required for patients with corneal scarring or other conditions such as keratoconus.
Are There Any Risks With DSAEK or DMEK Surgery?
With both DSAEK and DMEK, there are normal risks associated with eye surgery such as infection, bleeding, and swelling (your surgeon will discuss the risks in more detail), but there are also the risks of rejection and displacement.
Rejection occurs when the recipient’s immune system attacks the donated tissue. While this is a possibility, the small amount of tissue used decreases the likelihood of rejection. The rejection rate for DSAEK patients is about 10% while for DMEK patients it is less than 1%.
Another risk associated with DSAEK and DMEK surgery is when the transplanted tissue becomes displaced from the position into which it was implanted. If this happens, an operation will be needed to reposition the tissue or to replace it.
The procedure is done as an outpatient procedure and is done through a small incision on the side of the cornea. The diseased endothelial layer is peeled back from the back of the cornea, leaving the remaining healthy layers intact. The new corneal tissue (called a donor disc or graft) is then placed inside the eye through a small incision and positioned with an air or gas bubble in the place of the diseased layer. Several stitches may be placed if needed. The eye is then patched and shielded.
You will wear an eye patch immediately following surgery and may experience some mild discomfort. Over-the-counter medications can be taken as needed for any pain. You will be advised to lie down on your back and face the ceiling for the first 24-48 hours. Antibiotic and steroid eye drops will be prescribed by your corneal surgeon and detailed instructions will be given to you after the surgery.
For the first few weeks after surgery, your vision will be blurry as the cornea heals. Every patient heals at a different rate, so it is difficult to predict how long it will take for each patient’s vision to recover. Your corneal surgeon will be able to give you information about your eye’s visual potential and expectations. You will have a number of post-op visits to evaluate surgical outcomes and will have regular repeat visits afterward to monitor the progress of the transplant over time.