DSAEK and DMEK
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 corneal transplants).
DSAEK and DMEK are indicated when there is corneal clouding due to a dysfunction of the endothelium but where the other layers of the cornea remain healthy. With Fuchs’ endothelial dystrophy or when there is swelling of the cornea after cataract surgery, it is the endothelium which is compromised.
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 1/10th of a centimeter thick and is composed of three primary layers: the epithelium, the stroma, and the endothelium. The epithelium is a thin surface layer. The stroma is composed mostly of fibrous proteins and 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. Its job is to provide nutrients to the cells in the stroma and to make sure that the stroma has just the right amount of fluids. Too much fluid in the stroma can cause swelling of the cornea and decreased vision.
What is endothelial failure?
The cells of the corneal endothelium are very fragile. Two of the most common causes of endothelial failure are disease (like Fuchs’ Dystrophy) and decompensation following eye surgery, cataract or glaucoma surgery. Once an endothelial cell dies, it will not grow back. If an eye loses too many endothelial cells, it is not able to maintain the proper corneal thickness and clarity.
Corneal Transplant Surgeries
Corneal transplants are required for a number of corneal diseases and a variety of other reasons. Before and after transplant, you will need ongoing information and support. You do not need to go through the corneal transplant surgery and recovery alone. Our cornea surgery experts located in Erie, can help you understand what you will be facing with DSAEK, DMEK or traditional corneal transplant surgery, Penetrating Keratoplasty (PKP).
Prior to the patient’s surgery, the surgeon will prepare for surgery by determining the type of tissue to be used and selecting the technique needed to ensure the best surgical outcomes possible. The patient will begin pre-operative medications three days prior to surgery as instructed. The patient must not eat anything after midnight the day before surgery. On the day of surgery, the patient will arrive at the surgery center approximately one hour prior to surgery for preparation. In the operating room, the patient will be receiving anesthesia for relaxation and numbing medicine.
DSAEK and DMEK are performed through a small incision on the side of the cornea. DSAEK and DMEK involve peeling the diseased endothelial layer from the back of the cornea and leaving the healthy remainder intact (approximately 95%). Then, healthy corneal tissue (called a donor disc) is placed inside the eye through a small incision and positioned with an air bubble in the place of the diseased layer. Two or three stitches may be needed to close the initial incision. Surgery typically lasts 1 hour. At the end of the procedure, you stay lying on your back for another 40 minutes. You are then sent home with an eye patch. You will be directed to use eye drops frequently after the surgery. These are typically reduced at an appropriate time period following surgery. Visual recovery can change with each patient but usually takes three to six weeks for recovery. Please be advised that you might need a different prescription in your glasses or contact lenses to enhance your vision.
What is DSAEK?
DSAEK is a corneal transplant technique where the unhealthy, diseased, posterior portion of a patient’s cornea is removed and replaced with healthy donor tissue obtained from an eye bank. Unlike traditional corneal transplant surgery, the DSAEK procedure utilizes a much smaller surgical incision. DSAEK usually results in more rapid visual recovery and also reduces the risk of sight threatening complications that may occur with a corneal transplant, such as intraoperative expulsive hemorrhage or post-operative traumatic wound rupture.
What is the difference between DSAEK and DMEK?
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 to determine which is best for you.
Preparing for DSAEK and DMEK Surgery
Do not eat or drink anything for at least 8 hours prior to the surgery. Needed medications can be taken with a small sip of water. It is important to continue taking the medical eye drops (e.g. for glaucoma) that you would normally use on the same day as the surgery.
Advantages of DSAEK and DMEK compared to full-thickness corneal transplantation, Penetrating Keratoplasty (PKP)
• Improved vision
• The eye surface is kept intact, thus remaining more resistant to injury and infection
• There is minimal change in refraction because only the endothelial layer (~5% of the cornea) is replaced
• Suture-related problems are significantly reduced/can be eliminated
• Less risk than a traditional corneal transplant
• Visual recovery is significantly faster and better compared to corneal transplantation
• Less astigmatism compared to corneal transplantation
• Reduced discomfort
• Potential improvement in lifestyle functioning