Treatment for Corneal Disorders
The cornea is a clear "window" through which light passes on its way into the eye and provides most of the focusing power in the eye. Corneal injury, disease, or hereditary conditions can cause clouding, distortion, and scarring. Corneal clouding, similar to frost on a window-pane or dirty smudges on a camera lens, blocks the clear passage of light to the retina, reducing sight sometimes even to the point of blindness. In addition, corneal injury and disease can sometimes be intensely painful.
If the cornea becomes cloudy, the only way to restore sight is to replace or transplant the cornea. Corneal transplantation (keratoplasty) is the most successful of all tissue transplants. An estimated 15,000-20,000 corneal transplants are done each year in the U.S. The success rate depends on the cause of the clouding. For example, corneal transplants for degeneration following cataract surgery and those for keratoconus both have high success rates, while corneal transplants for chemical burns have lower success rates.
Corneal tissue for transplant comes from an eye bank. Donor corneal tissue is readily available in the United States. The operation consists of a transfer of the clear central part of the cornea from the donor's eye to the patient's eye. Soon after the operation, the patient can resume activity.
Return of the best vision after corneal transplant surgery may take up to a year, depending of the rate of healing and the health of the rest of the eye. A contact lens may be required to obtain one's best vision after corneal transplant surgery. As in any kind of transplant, rejection of the donated tissue can take place. The major signs of rejection are redness of the eye or worsening of vision. If these occur, prompt return to an ophthalmologist is necessary even if it is years after the original operation.
DSEK (Descemets Stripping Endothelial Keratoplasty)
Descemets Stripping Endothelial Keratoplasty" or "DSEK" is surgery to replace just the diseased endothelial (innermost) layer of your cornea. Regardless of the name, the idea is to remove the least amount of your corneal tissue and replace it with healthy donor tissue to clear the swelling of the cornea and restore your vision. The advantages of this procedure over a conventional full thickness corneal transplant include the following:
- Faster visual recovery.
- Less likely to require a strong glasses prescription with astigmatism;
- Less likely to require a contact lens to achieve one's best visual acuity
- Less likely to reject the donor tissue.
- Less prone to future injury.
- Safer intra-operative procedure.
Eat a light meal and take your usual medications.
Please use whatever medical eye drops (for example, for glaucoma) that you would normally use for the operative eye on the same day as the surgery.
The surgery is usually performed under conscious sedation with a local anesthetic of your eye. Our Certified Registered Nurse Anesthetist (CRNA) will administer a sedative intravenously, and then after you are sedated, he/she will completely numb your eye. Patients typically do not remember the numbing procedure, and once the eye is numb, they should not experience any discomfort during the surgical procedure. This also prevents you from seeing the surgery or moving the eye. The CRNA also gives you medicine by vein in order to keep you relaxed and a little sleepy during the surgery. Using local anesthesia avoids many of the risks to your heart or lungs that complete general anesthesia involves.
During the surgery a single line incision with a length of only 5 millimeters is made in the sclera (the white part of the eye), a pocket is formed into the cornea, and the diseased endothelial layer of your cornea will be removed (descemets layer). The healthy donor endothelium and back layer of the donor cornea is then placed through the incision and pocket and placed into position on the back surface of your cornea to replace the diseased tissue which was removed. The initial incision is then closed with one to three small sutures and the procedure is completed. A small air bubble is left inside the eye to help insure the stability of the donor transplant tissue and it is most effective when you are lying down on your back, facing the ceiling. This air bubble is simply absorbed and disappears over about 48 hours.
The surgical procedure will take about one hour to perform, slightly longer than a standard full thickness corneal transplant (45 minutes). You will be in the recovery room for about an hour after the surgery, lying flat on your back facing the ceiling. Your may then return to the operating room to perform the final stage of the procedure which typically takes an additional 15 minutes. Thus the entire visit can take as long as 3 - 4 hours before you are ready to go home. Surgery is usually done as an outpatient procedure at the Spokane Eye Surgery Center and you are sent home with a patch on your eye that same afternoon. You should have minimal discomfort after surgery, and standard over-the-counter pain medications can be taken if necessary. Keep the eye patched until you are seen the next day.
Immediate Post-operative Instructions
We will advise you to lie flat on your back, facing the ceiling as much as possible after the surgery for the first 24 hours. You are able to go to the bathroom or to sit up for eating meals as much as necessary in that first 24 hours after surgery and it is not a danger to your transplant to do so, but whenever possible, try to rest in bed lying on your back and facing the ceiling. (one pillow is OK). This will allow the small air bubble inside the eye to best stabilize the transplant tissue.
Post op Visits Schedule
You will return to see your doctor the next day. The patch will be removed and your eye will be examined. You will be placed on antibiotic and steroid drops to prevent infection and to help with healing. This first visit after surgery is primarily done to check the pressure and to be sure that the donor disc is in good position. You will have a brief visit to the clinic one week after surgery, and then again at one and three months.
Immediately after surgery, we like you to be lying down on your back facing the ceiling and resting as much as possible for the first 24 hours. (see comments above)
Go slowly on the food the night after you have had surgery, as anesthesia sometimes can cause people some nausea.
The day after surgery, the patch is removed and does not need to be re-applied. You will, however, be asked to wear a protective shield over the eye (without a patch) at night while sleeping for 1 week. No protection is needed during the day, but if you normally wear glasses for the other eye, go ahead and wear them.
Most normal activities are permitted even the first day after surgery. You can shower and wash your hair. You are at risk for infection for the first two weeks after surgery, so do not do activities that put you at risk for infection (like gardening, working in dirty environments etc.) Just use common sense and it will be fine. Finally, avoid any activities that may lead to taking a direct hit to the eye.
No sports activities of any kind for 2 weeks after surgery. No swimming under water for 4 weeks, but doing water exercises (head always out of water) is fine after two weeks.
The day after surgery, the patch will be removed and the vision will be absolutely terrible! This is normal.
Expect that the vision will allow you to only see well enough to count fingers at about 2 feet away, but not much better than that. The reason why the vision is so poor is that the donor tissue is still swollen and although it starts to clear your cornea nearly immediately, it does so in patches, and those clear patches of cornea are rarely over the visual axis on the first day.
By one week after surgery most patients are aware that their cornea is getting better and their vision is clearing.
By one month the vision is typically much improved and patients feel that success is at hand. A gradual improvement typically continues over the next three months.
By one year after surgery, over 65% of patients have 20/40 or better vision. The patients that have no other ocular problems (like macular degeneration or other retinal disease) have the best vision of all after DSEK surgery.
The vision continues to improve over time, with many patients improving their vision even from one to two to three years after surgery.
The ultimate vision after DSEK surgery will depend more upon the health of the patient's retina and central vision of the macula than upon the clarity of the cornea, as nearly all DSEK patients attain a clear cornea with good surface focus after this surgery. Vision of 20/20 is possible, but even with a crystal clear cornea, the vision is dependent upon the function of the retina and may not attain 20/20. It is most important to remember that while the vision will be better after surgery than it was before surgery; there is high variability between patients on the amount of vision improvement and the rapidity of vision improvement. Generally speaking, the patients that are younger than 65 years old, and the patients that start off with vision better than 20/60 prior to surgery have the fastest visual recovery. Some of our patients have been 20/25 at just one week after surgery, but these are the exceptions. Patience is still a virtue, even with DSEK surgery.
Donor Disc Dislocation
A one day post-operative exam will be done to make sure the donor tissue disc is in proper postion. If the donor disc is NOT in proper position, then the disc will have to re-positioned by the surgeon. The risk of this happening is between 2% and 4.5%. Nonetheless, this is a real risk of DSEK surgery. Fortunately, a dislocated donor disc can be successfully re-positioned with good function and restoration of vision over 90% of the time. In the worst case scenario, if the disc cannot be successfully repositioned with a simple air bubble, we will have the option of either trying a new donor disc or resorting to a conventional, full thickness corneal transplant.