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New Alternative to Full Corneal Transplantation: DSAEK

By: CNY Eye Care
From: CNY Eye Care
Posted: January 5th 2008

DSAEK: Descemet's Stripping Automated Endothelial Keratoplasty

The cornea is a transparent dome on the front of the eye. Corneal edema (swelling) produces decreased vision due to loss of transparency of this normally clear tissue. The swelling is due to a loss of endothelium, a thin layer of cells found on the back surface of the cornea. These cells are not capable of dividing or repairing themselves. The only treatment for visually significant corneal swelling is to replace these cells.

In the past, the gold standard for replacing endothelial cells would be to perform a full thickness corneal transplant. We have a handout which covers the risks and benefits of this procedure in a comprehensive manner. In summary, full thickness corneal transplantation requires the complete removal of your cornea followed by replacement with a donor cornea. The edge between the new cornea and old cornea takes years to heal so the new cornea is sutured in place with very fine stitches left in place indefinitely to maintain strength and stability. After the operation, it usually takes several months to several years to obtain your best vision. It is very difficult to predict the final curvature of the cornea; so after surgery, glasses or contact lenses are required in the vast majority of cases. If the stitches break, it may be uncomfortable, described like sand in the eye, and removal of the stitches may change the curvature of the cornea, requiring new glasses. In addition, the broken stitches may produce a corneal infection requiring use of antibiotics to treat the infection and can rarely lead to graft failure.

Full thickness corneal transplantation has been the standard of care for many years and most physicians are very familiar with the postoperative care. It provides excellent vision with the appropriate glasses or contact lenses. It does require frequent visits to the doctor to measure the cornea, prescribe glasses and take care of the stitches.

Recently a new procedure has been developed to replace the endothelial cells that does not require a full thickness replacement of the cornea. In the DSAEK procedure, a thin piece of donor corneal tissue containing the endothelial cells and posterior stroma is placed in the eye through a small incision on the side of the eye. This tissue adheres to the back surface of the old cornea and clears the corneal swelling.

The advantages of DSAEK are that extensive stitching of the cornea is not required and the eye heals more quickly. Although glasses will still be required after the operation, they may be much thinner as the power of the eye after surgery is much more predictable. In addition, the surgery is safer as the new cornea is inserted through a small incision rather than a complete opening of the front part of the eye reducing the chance of a devastating hemorrhage during the surgery or infection afterwards. Since we use a small incision, the eye is left stronger so that if it is inadvertently struck there is less likelihood of a serious injury.

The disadvantages of the DSAEK procedure is that the new endothelium is manipulated more directly than in a full thickness corneal transplantation potentially producing more damage and possibly resulting in graft failure. There is a 25% chance that the new tissue will not adhere properly requiring repositioning, or in less than 1% of cases, re-operation. The long term survival of this tissue has not been fully studied. The cornea is also left much thicker than the original due to the addition of tissue to the posterior aspect of your current cornea. This may make it more difficult to follow glaucoma. Further, although the vision is much better than before the operation, ultimately it may not be as crisp as in a full thickness corneal transplant. However in some studies, patients preferred the DSAEK operation, even with slightly worse vision, because it healed faster, it did not take as long to get glasses, and they could see better without glasses than in patients with full thickness corneal transplantation.

In order to make the new tissue stick onto the back of the old cornea, an air bubble is used to completely fill the front part of the eye for an hour after surgery. After that time the air is partially released and left overnight. During the first twenty-four hours, it is important to stay on your back as much as possible to keep the air bubble positioned correctly, anchoring the new tissue in place. When you are seen the next day, the position of the new tissue will be checked. It may be necessary at that appointment or the next appointment one week later to reposition the new tissue by placing a new air bubble. Once the tissue sticks, it remains in place so the most critical time is the first six weeks.

After DSAEK, the vision clears faster than the full thickness corneal transplant operation and you can return to your normal activities within two weeks with the exception of swimming. Like full thickness corneal transplantation, eye drops are required for at least a year and more often for the rest of your life to prevent graft rejection, where the body recognized the tissue as being foreign and can react against it. Fortunately graft rejections are very unusual (less than 10% of the time) and if they do occur, can be treated successfully in the majority of cases with frequent eye drops and occasionally oral medications. The cornea is a privileged site where powerful immunosuppressive medications are rarely necessary to prevent graft failure.

We are pleased to bring this new procedure to Central New York and look forward to working with you to help improve your vision. If you have any questions, please do not hesitate to contact us.