What is DMEK?
Descemet’s membrane endothelial keratoplasty, also known as DMEK, is an advancement in the field of corneal transplant surgery. During a DMEK procedure, only the innermost layers of the cornea are replaced, instead of the whole thickness of the cornea. This technique is much less invasive than a traditional penetrating keratoplasty, which requires replacement of the full cornea and is one of several selective corneal transplant procedures now commonly performed.
Reasons for DMEK
DMEK is often performed to improve vision that has been compromised by Fuch’s’ dystrophy, an inherited eye disease that affects eyesight and may cause pain or sensitivity in the eyes, or to treat bullous keratopathy, a persistent corneal swelling that affects vision.
The DMEK Procedure
After the patient’s damaged tissue is removed from the cornea, the donor replacement tissue is carefully placed at the rear of the cornea. Few or no sutures are needed. The DMEK procedure takes only half as long as a penetrating keratoplasty.
Since only inner layers of the cornea are replaced in a DMEK procedure, patients typically recover much more quickly than patients who have undergone a more traditional corneal transplant. Most DMEK patients achieve improved visual acuity within 1week after the surgery and very few suffer complications.
Advantages of DMEK
DMEK (Descemet Membrane Endothelial Keratoplasty) is a less invasive corneal transplant surgery than Penetrating Keratoplasty. Typically used for the treatment of corneal swelling, DMEK is a surgical technique that replaces only the diseased or damaged portion of the cornea. It is a similar technique to DSAEK, however the corneal graft is much thinner and replaces exact layers that are removed. In DMEK, the inner layer of the cornea, called the endothelium, is removed leaving the rest of the cornea undisturbed. In a traditional cornea transplant, doctors make a full thickness incision by creating a circular opening in the front of the eye. This requires many sutures to secure the transplant. In DMEK, the new cornea is inserted through a small incision that requires only one suture for closure. The graft is then supported by an air or gas bubble until it stabilizes.
The benefits of replacing one layer are many including:
- Shorter post-op recovery
- Faster visual recovery
- Less chance of rejection
- Less invasive re-operation if necessary.
DMEK surgery is typically covered by insurance and takes less than an hour to perform. It can even be combined with cataract surgery when necessary. As an outpatient procedure in our surgery center, patients return home within hours. After surgery, you will be advised to follow some specific instructions to maximize the chance of success. The initial visual recovery takes approximately 1 week, after which vision improves gradually for several weeks more. Patients can regain excellent levels of vision. You will return to your surgeon’s office one day, one week and one month after surgery, then periodically thereafter. During this time patients use a tapering dose of steroid eye drops to prevent rejection.
What is Corneal Swelling?
Swelling of the cornea can result from premature aging (Fuch’s Dystrophy) or damage to the cornea’s inner lining called the endothelium. The cells in the endothelial layer are responsible for pumping fluid out of the cornea, keeping it clear and compact. When the number of these cells is reduced, the cornea becomes swollen and cloudy, leading to blurred vision. These are conditions where DMEK can be most helpful in restoring vision. DMEK does not work in scarred or irregularly shaped corneas.
What to Expect Before Surgery
Before your surgery, the surgeon will meet with you in our office. An examination will determine if surgery is the appropriate treatment option. Doctors perform testing and measurements at the time of your appointment. Our office will review the cost of the procedure with you. Most insurances and Medicare cover much of the cost. Your surgeon will explain the post-operative care and will address any other questions you might have about DMEK. Your surgeon will prescribe antibiotics and other eye drops before your surgery. It is very important not to eat anything after midnight on the night before your procedure.
What to Expect During Surgery
Your surgeon will typically perform DMEK with mild sedation. Numbing medication is also used so there is little or no discomfort. Using sophisticated instrumentation, the donor cornea is prepared and placed in the recipient’s eye. This new graft is then carefully unfolded and supported by an air or gas bubble. It presses against the recipient’s cornea while the patient is lying on their back. The bubble takes the place of sutures and is only necessary for a short period of time after completion of the surgery. After the surgery, you will be asked to lie flat on your back for at least 24 hours to ensure success of the surgery.
What to Expect After Surgery
Your surgeon will check your healing on the first day after surgery. Your vision is not expected to be improved immediately at this visit. In fact, it is usually worse on your first post-op day. There is minimal pain after surgery. Some light sensitivity and scratchiness can be expected. Visual recovery varies depending on the severity of your corneal cloudiness before surgery. Most patients notice improvement in their vision during the first two weeks after surgery, with continued improvement during the next four to six weeks. This is faster than the many months and often years of rehabilitation needed after a traditional penetrating transplant and quicker than even DSAEK surgery. You will likely have a change in your eyeglass prescription at some point after the surgery.
Because the new transplant does not require sutures to stay in place, there is less induced irregularity or change in the curvature of the recipient cornea (astigmatism). This translates into faster rehabilitation of vision, fewer postoperative physical restrictions and a stronger eye after surgery, which is less susceptible to injury from trauma. The surgical incision is smaller and does not alter the eye’s integrity. There is also less concern about sutures breaking and causing infections.
You will usually be able to resume most physical activities like light exercise and applying eye makeup 1 week after surgery. Swimming and more intense exercise such as weight lifting can be resumed 4 weeks after surgery.
Risks of DSEK
The visions results of DSEK are good, but there is increased risk that the corneal graft, which is extremely thin, will not attach properly and may be rejected.