Corneal Transplant – DSAEK & DMEK
Corneal Transplant – DSAEK & DMEK (Descemet’s Stripping Automated Endothelial Kerotoplasty) (Descemet’s membrane endothelial keratoplasty)
Descemet’s stripping automated endothelial keratoplasty (DSAEK) and Descemet’s membrane endothelial keratoplasty (DMEK) are partial thickness corneal transplants which replace primarily the endothelium (innermost portion of the cornea) rather than the full thickness of the cornea (as in standard PKP transplants)
DSAEK and DMEK are indicated when there is corneal clouding due to a dysfunction of the inner corneal lining but where the other layers of the cornea remain healthy. Typically this occurs in conditions such as Fuchs’ endothelial dystrophy where the inner lining is naturally weak and worsens with age. It also may occur after cataract surgery where the endothelium was stressed and could not recover.
What is the endothelium and how does it work?
The cornea is the clear dome that makes up the front part of the eye. It is about 600 microns thick and is composed of three layers: the epithelium, the stroma, and the endothelium. The epithelium is a thin surface layer. The stroma is the transparent body of the cornea acts like a sponge, absorbing fluid from inside the eye. The endothelium is a single layer of cells coating the inside portion of the cornea. It maintains transparency of the cornea by providing nutrients and ensuring the stroma has just the right amount of fluids. If the endothelium fails then the cornea swells becoming cloudy. This can decrease vision and eventually lead to pain. Loss of endothelial cells is irreversible and can only be corrected with transplantation surgery.
Advantages of DSAEK and DMEK compared to standard PKP corneal transplantation
The DSAEK transplant technique has been shown to enable good vision and to have many potential advantages over full thickness transplants, including earlier return of vision, less refractive errors, fewer serious complications, a more stable eye, and lower chance of rejection. This is because the incision is only between 2.2 to 5 mm, requiring only 2 sutures which can be removed in 1 to 2 months. This allows visual rehabilitation to start at 1 to 3 months versus 18 months with full thickness corneal transplants. Because the incisions are small the eye is mechanically stronger and more resistant to injury in the unlikely case of a future blunt trauma. It is likely that the patient’s best vision will still be obtained with glasses and less commonly a contact lens. In contrast to PKP, optimal vision will be easier to achieve given the smoother surface of the cornea
What is the difference between DSAEK and DMEK?
DMEK is very similar to DSAEK as they are both partial thickness transplants that replace the diseased inner endothelial lining of the cornea. DSAEK is a procedure that has gained significant popularity over the last decade and replaces the inner lining with a 100 micron donor graft. DMEK is a newer procedure, that requires a smaller 2 millimetre incision, typically no sutures, and uses only a very thin 10 micron graft. DMEK tends to give better visual results, less chance of rejection, and a quicker recovery; however, donor disc dislocations and failures are more common. In summary, the visual outcome may be better with DMEK but patients are more likely to require a 2nd procedure to ensure the graft is functioning in a good position. Depending on the individual condition of your eye Dr. Bujak will be able to guide you as to which procedure is best for you.
Post-operative care
For both DMEK and DSAEK, patient positioning, follow up, and use of eyedrops is important to give the best chance of a successful result. In the first 2 to 3 days post surgery patients will need to lie on their back looking up at the ceiling as much as possible. There are no sutures holding the graft in place and only an air bubble in the eye holds the graft in place that is why positioning is so important. Most patients have a friend or family member assisting them with daily activities in the first 3 days after surgery. Follow up is important and patients are typically seen 1 day, 1 week, 1 month, 3 months, 6months, and yearly after surgery. Eye drops are used to minimize chance of infection and graft rejection. They typically start 4 times daily and are gradually reduced to once daily.
When should the surgery be done?
DSAEK and DMEK are elective surgeries meaning that the patient ultimately decides when they are ready to proceed with surgery. Often patients will choose to undergo surgery when their vision is sufficiently blurred or they are troubled by glare and haloes. If the patient is left untreated then the cornea may continue to swell and eventually become painful. If the corneal swelling is significant and is left for an extended period then scarring of the cornea may occur. For best vision results it is ideal to do surgery before this irreversible scarring occurs.