DISCLAIMER: Information presented here should not be considered inclusive of all proper methods of care or exclusive of other methods of care reasonably directed to obtain the same results. The ophthalmologist in light of the individual circumstances presented by the patient must make the ultimate judgment regarding the propriety of any specific procedure or treatment. This information is intended solely to provide general information about corneal surgery. It does not constitute medical advice and should not be relied upon for medical decision-making. For medical advice, please consult with your personal physician.
Because DSEK can be technically challenging and is a relatively new corneal surgery, patients considering the procedure should determine whether their corneal specialist has completed an appropriate training course, including observation of a surgeon experienced in DSEK.
Reasons You May Need DSEK
The human cornea is composed of five layers, the outer or epithelial layer, Bowman’s membrane. the middle or stromal layer (which comprises about 90 percent of the total corneal thickness), Descemets membrane, and the inner or endothelial layer.
The endothelial cells can be lost due to aging, from inherited diseases (such as Fuchs' Corneal Dystrophy), from trauma, or from previous intraocular surgery. If a critical number of endothelial cells are lost, and the cornea becomes swollen and cloudy, medical therapy is usually not helpful and a corneal transplant operation is indicated. The remainder of the corneal layers, the stroma and the outer epithelium, are usually healthy. A large number of patients requiring corneal transplant surgery have these sorts of problems where only the endothelial cells have been injured or lost.
DSEK vs Penetrating Keratoplasty
Traditional corneal transplant surgery (penetrating keratoplasty) has consisted of removing the entire diseased cornea and replacing it with a full thickness donor cornea. This surgery was first developed one hundred years ago, and its success rate is based on numerous refinements to the same basic technique.
For many patients, only the diseased or missing endothelial cells need to be replaced in order to restore vision, as the stroma and epithelial layers are normal. DSEK replaces only the endothelial cell layer. A thin button of donor tissue containing the endothelial cell layer is inserted into the eye and placed onto the back surface of the cornea. This technique appears to be a significant improvement over the traditional operation. The surgical skill and expertise required is the same, but the surgery itself takes less time with an experienced surgeon, involves a smaller surgical incision, requires far fewer or no sutures, heals faster and more reliably, and vision returns faster.
The advantage of the traditional corneal transplant operation is its long and successful track record. The rate of rejection is very low. It is relatively easy to combine other procedures with it such as cataract extraction or glaucoma surgery. The disadvantages of the traditional corneal transplant operation are the time involved in performing the actual operation (45 to 60 minutes), the difficulties in suturing the new cornea in place, and problems with the sutures which may come loose, cause infections, or cause astigmatism. The astigmatism after traditional corneal transplant surgery can be so significant that eyeglasses alone won't give adequate vision and some patients ultimately require contact lenses or additional surgery. Because the traditional procedure leaves a large wound in the eye patients have a risk of rupturing the wound from mild or incidental bumps or trauma, even several years after the surgery. Recovery of vision can take 6 to 12 months.
There are several significant advantages to DSEK when compared to penetrating keratoplasty. Once the surgeon is skilled in the technique, the operation is faster. The wound is smaller and closer in size and location to a cataract surgery incision. The smaller wound is more stable and less likely to break open from inadvertent trauma. Because the wound is smaller and requires far fewer sutures, there is very little postoperative astigmatism that can delay the visual recovery. Some surgeons utilize an entrance wound that does not require sutures to close. The maximum return in vision takes only about 3 to 4 months following DSEK. Since only the thin inner layer of the cornea is replaced, over 90 percent of the patient's own cornea remains intact contributing to greater structural integrity and a reduced incidence of rejection.
DSEK is not for everyone. Some patients with corneal scarring or other conditions are not suitable candidates for DSEK. There are risks involved with the DSEK operation. Since the procedure is relatively new, there is no long-term follow-up. There is a risk of the thin donor tissue graft button becoming displaced within the first few days or weeks after surgery and requiring a return trip to the operating room to reposition it. If the DSEK operation fails, the operation can be repeated. If the DSEK fails, either after one or multiple attempts, a traditional corneal transplant is still an option.
Risks and Complications of DSEK Surgery
The general risks of DSEK are similar to the traditional corneal transplant operation: risk of hemorrhage in the eye; infection; swelling of the retina causing temporary or permanent blurring of vision; retinal detachment; glaucoma or high pressure in the eye; rejection of the transplanted tissue; chronic inflammation; double vision; droopy eyelid; loss of corneal clarity; poor vision; total loss of vision; or even loss of the eye. Rarely, the transmission of infectious diseases can occur, although the corneal donor is routinely tested before the tissue is approved and released for transplantation.
There may also be complications from the local anesthesia including: perforation of the eyeball; damage to the optic nerve; droopy eyelid; interference with the circulation of the blood vessels in the retina; respiratory depression; and, hypotension. On rare occasions, useful vision can be permanently lost.