Welcome to the patient information area of our DLEK-DSEK website. In this section, you will find general information regarding the problem of corneal swelling (edema) to help you better understand your eye condition. We also explain the various methods of surgery to treat corneal edema, and answer some of the more common questions that we encounter.
Since 1999, we have worked very hard to develop a specialized form of surgery (DLEK and DSEK/DSAEK) to treat your condition. We hope that this section gives you a better understanding of why we believe this surgrical technique is superior to more traditonal forms of corneal transplantation.
What is the cornea and how does it work?
The cornea is the clear dome that makes up the front of your eye. Normally, when looking straight on at the eye, you look right through the cornea and see the colored iris and black pupil of the eye. From the side view of the eye, you can best see the clear dome of the cornea.
The cornea is only about 1/20th of an inch thick (550 microns) and is made up of three main layers of tissue. They are the following:
1. The surface epithelial layer:
This is the layer that is on the surface, like the “skin” of the eyeball, and is about 6 cell layers thick. It is the layer that easily heals and replaces itself when injured such as after a corneal abrasion. There is a lot of pain with an abrasion because the corneal nerves lie just below the surface and are exposed when there is a break in the corneal epithelial layer. The epithelial layer of the cornea must be perfectly smooth and clear in order to provide for good focusing of light and good vision.
2. The central corneal stroma layer:
This layer of tissue makes up about 95% of the thickness of the cornea. The stroma tissue acts like a sponge; it absorbs fluid from inside the eye (the aqueous fluid) to get nutrients. It can absorb up to twice the normal thickness, but the more fluid above normal levels that is absorbed, the cloudier the cornea becomes and the worse the vision becomes. Although the stroma is a very strong, it is very slow to heal and usually heals with a scar which can cause light scatter.
3. The inside, back surface endothelial layer:
The endothelium is possibly the most important layer of the cornea in keeping the cornea healthy. It is a very thin layer, only one cell layer thick, and is extremely fragile. Any touch or surgery near the endothelial cells cause those cells to die, and, unlike the surface epithelial cells, the endothelium does not replace itself. It is the endothelium which regulates the amount of fluid which enters and exits the corneal stroma tissue. The endothelium has microscopic pumps that work to keep the cornea clear. So for every drop of aqueous fluid that is sucked up by the stromal tissue, an exact equal amount of aqueous fluid is pumped out of the cornea back into the eye by the endothelial cells. This is the normal system of fluid flow into and out of the cornea to provide nutrients to the corneal tissue and keep the cornea clear. If too many endothelial cells are lost from disease (e.g. Fuchs’ dystrophy) or destroyed from surgery (e.g. cataract or glaucoma surgery), then there are not enough pumps available to keep up with the amount of fluid absorbed by the stroma, and the cornea becomes more swollen. The more swelling of the cornea, the more cloudy the vision. This can be likened to looking through a steamy window. Restoring the necessary number of healthy endothelial cells restores the pumping action, gets rid of the swelling of the cornea and restores the vision.
The cornea is living tissue, which requires oxygen and nutrients, just like every other living tissue in your body. The cornea gets its oxygen from the air dissolving in the tear film and it gets its nutrients from the fluid circulating on the inside of the eye. (the aqueous fluid). The endothelial cells require oxygen in order to do their job of pumping fluid out of the cornea. When the eyes are closed during sleep, there is a near shut-down of oxygen to the cornea, and the pumping action of the endothelium is reduced. The cornea is therefore thicker (more swollen) in the morning, than it is later in the day. In normal corneas with a surplus of endothelial cells, this variation in thickness has no effect on vision. However, in eyes with a marginal number of endothelial cells, this variation in corneal thickness often explains why the vision is worse in the morning after awakening than it is later in the day when the eye has had more oxygen to recover.
Can the cornea become swollen from cataract surgery?
All cataract surgery causes some damage to the endothelial layer. Most of the time that cell loss is less than 10% and there are plenty of endothelial cells left to keep the cornea clear. However, one of the most common situations for corneal transplant surgery is the patient that underwent cataract surgery and then the cornea became swollen afterwards. The explanation for this is that the endothelial layer of the cornea was damaged during the cataract surgery and there were not enough healthy endothelial cells left over to keep the cornea clear.
Most of the time, we see patients that have Fuchs’ dystrophy of a mild or moderate degree (say about 1,000 cells) who undergo uncomplicated cataract surgery and the endothelial cell loss is more than expected and the corneal tissue swelling does not clear. Occasionally, the cornea will be clear for a few months, but as more cells die over time due to the Fuchs’ dystrophy, the cornea then becomes cloudy and needs a transplant. Occasionally, the patient does not have Fuchs’ dystrophy, but the cataract surgery was unusually complicated and there was more damage to the endothelial layer than expected, resulting in corneal swelling. This can happen even with the best of cataract surgeons and the best of cataract surgeries and is one of the known risks of cataract surgery.
Fortunately, whether the cause of corneal swelling was from Fuchs’ dystrophy or complicated cataract surgery, the swollen cornea can be fixed with a corneal transplant, providing a replacement of the patients damaged corneal endothelial cells with healthy donor endothelium.
What are the options for corneal transplantation?
There are basically 3 options now for replacing the endothelial layer for patients that are suffering from a swollen cornea: (1) a full thickness conreal transplant or PK, (2) Deep Lamellar Endothelial Keratoplasty or DLEK and (3) Descemet's Stripping Endotheliel Keratoplasty or DSEK
- Full thickness Corneal Transplant Surgery of “PK”:
Over the past 100 years, the only method of replacing the endothelium was with a full thickness corneal transplant. This method is called a “penetrating keratoplasty” or “PK”. In this method, the patients central cornea overlying the pupil area is cut out with a cookie cutter instrument called a “trephine”. This full thickness circular “button” of tissue contains the diseased endothelial layer, but also the swollen but healthy stromal layer and the healthy surface epithelial layer. This leaves an 8 millimeter diameter hole in the central cornea which must be plugged by the donor tissue. The surgeon then cuts a similar size 8 or 8.25 mm diameter “button” of donor corneal tissue which contains healthy endothelium and other healthy layers and transplants this entire full thickness tissue into the hole of the patients cornea. He then sutures the tissue in place with either 16 separate sutures or a single running looping suture around the edges of the 8.0 mm edges to make the junction between the donor and the patient tissues water-tight. This circular wound takes a long time to heal and the sutures need to stay in place for at least a year or more. The sutures are under the surface, and so the patient does not feel them after a week or two. Nonetheless, the sutures cause the surface of the cornea to be somewhat irregular and this limits the patient from seeing their best until the sutures are completely out, and this can be a year or longer. Once the sutures are out, the suture can still be irregular, and about 15% of patients require a contact lens (instead of glasses) in order to see their best. Finally, the sutures in the cornea pose a risk of developing rejection and infections as long as they are present.
-The DLEK and DSEK/DSAEK procedure are described in detail in the other areas of this website
Instructions for DLEK/DSEK patients
You have chosen to have a special surgery to replace just the diseased endothelial layer of your cornea. We originally called this surgery “Deep Lamellar Endothelial Keratoplasty” or “DLEK”, and the modification of this surgery is called “Descemet’s Stripping Endothelial Keratoplasty” or “DSEK”. 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.
Before Surgery:
Do not eat or drink anything for at least 8 hours prior to the time of your surgery. You may take any medication pills that you need to take with a TINY sip of water.
Please bring your DLEK or DSEK surgical consent form to the hospital with you and sign it there in front of the nurses.
Please use whatever medical eye drops (eg for glaucoma) that you would normally use for the operative eye on the same day as the surgery.
The Operation:
The surgery is usually performed under local anesthesia where the anesthesiologist only puts you to sleep for about 5 minutes and during that time we give some anesthetic shots to completely numb the eye. You do not even remember the shots and the operation is completely pain free. The shots also prevent you from seeing the surgery or moving the eye. The anesthesiologist also gives you medicine by vein in order to keep you happy 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. (General anesthesia is when you are completely asleep during the surgery.) However, if you have a strong preference for general anesthesia, (or if Dr. Terry decides that general anesthesia is safer for your particular case) then this can be done.
During the surgery a single line incision with a length of only 5 mm 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. 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). If you also have a cataract of the lens of the eye, then cataract surgery can be performed at the same time as DLEK/DSEK surgery. If cataract and DLEK/DSEK surgery are done, then the surgery takes about one and a half hours. You will be in the recovery room for about an hour after the surgery, lying flat on your back facing the ceiling, before your family can see you, and then kept another hour after that. Surgery is usually done as an outpatient procedure at the hospital 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. You may also be given other pill medications to take for the eye if indicated. Keep the eye patched until Dr. Terry sees you the next day.
Immediate Post-operative Instructions:
We request that you try to stay lying down on your back, facing the ceiling as much as possible after the surgery for the first 24 hours. (Do not sit up watching TV or working on a computer that first night.) You are quite free to stand up and walk around for going 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 Dr. Terry 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 will only take about 15 to 30 minutes, and 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. These visits can be done by your local referring doctor if it is more convenient for you and if your referring doctor agrees with this. Later visits at 6, 12, and 24 months will require extra testing of your vision and of the cornea and will take about 45 minutes to an hour. We would like to do those visits here at Devers Eye Institute, but if it is more convenient for you and if your referring doctor agrees, those visits also can be done locally by your referring doctor for your convenience. We will of course see you at any time that you have any concerns, questions or problems after your surgery.
The tests that you will have performed at the pre-op visit and after surgery at the 6, 12, and 24 months visits are a vision test, a check for glasses, examination with the standard clinic microscope, a pressure check, and measurements of your cornea with various optical machines which record light reflections from the cornea (corneal maps). None of these tests will be difficult or uncomfortable for you. Once again, if your referring physician is able and willing to perform these tests and send the information to us, then your pre-operative testing and post operative testing can be done locally by your referring doctor for your convenience.
Medication Dosage and Schedule: (Note: you can use your various drops at the same time, just separate them from each other for about 5 minutes so each drop has time to sink in.)
Prednisolone Acetate 1%: (a milky white drop): (shake it up really well before application)
Begin using this drop FOUR times a day (breakfast, lunch, dinner and bedtime) from the first day post-op until 3 months after the surgery. From 3 to 6 months after surgery, use it 3 times a day. From 6 to 9 months after surgery, use it 2 times a day. From 9 to 12 months after surgery, use it once a day. After that your doctor may discontinue it or wean it down in frequency even more or switch to another medication.
This drop (Prednisolone acetate 1%) is what keeps your body from rejecting your transplant tissue, and so it is extremely important that you do NOT stop taking this medication unless advised by your corneal doctor.
Vigamox (a yellow color antibiotic drop in a small bottle)
Begin using this drop FOUR times a day (breakfast, lunch, dinner and bedtime) from the first day until 2 weeks after surgery, and then stop using it.
This drop (Vigamox) is an antibiotic and keeps your eye from getting infected.
Refresh pm Ointment: (a preservative free lubricant for the eye) (this is an over-the-counter item)
Begin using this ointment at bedtime as the last thing you put in your eye before sleep. Use it for 2 months after your surgery and then you can stop using it if your eye feels comfortable without it.
Please use any other eye medications (especially any glaucoma medications) that you were using prior to your surgery, use them on the day of surgery and start them again the morning after surgery when the patch is removed.
Activities:
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. Start with soup, then progress to solids if comfortable.
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 about 5 days. No protection is needed during the day, but if you normally wear glasses for the other eye, go ahead and wear them.
Normal activities are permitted even the first day after surgery after you see Dr. Terry and he takes the patch off. You can then shower, wash your hair, and do normal activities like shopping etc. However, 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, cleaning out stalls or attics, 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. (eg playing with small children, wrestling with animals, etc!).
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.
Vision Expectations:
The day after surgery, the patch will be removed and the vision will be absolutely terrible! This is normal.
(It is not like
Expect that the vision will allow you to only see well enough to count my 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 the vision is about 20/100 and most patients are aware that their cornea is getting better.
By one month the vision is usually around 20/60 and all patients feel that success is at hand.
By three months, the vision is usually around 20/50 or better, but this is highly variable, with many patients achieving 20/30 or so.
At one year after surgery, over 65% of patients have 20/40 or better vision. (This is the vision that allows one to drive a car with no visual restrictions). The patients that have no other ocular problems (like macular degeneration or other retinal disease) have the best vision of all after DLEK surgery.
The vision continues to improve over time, with many patients improving their vision even from one to two to three years after surgery.
I have given you the “average” visions at various time gates after surgery to give you some idea of what you might expect. The ultimate vision after DLEK surgery, however, 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 DLEK 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 DLEK surgery.
Donor Disc Dislocation:
On that first day after surgery, all that I plan to do is check to make sure that your donor tissue disc is still in the same position that I left it at the end of the surgery. If the disc is in good position, then I will be happy and you will heal very well.
If the donor disc is NOT in proper position, then the disc will have to re-positioned by me, and that means a visit to the minor operating room in our office for a 15 minute procedure. The risk of this happening is between 2% and 4.5% in my DLEK and DSEK program, and this is the lowest rate of dislocation of any DLEK or DSEK surgeon in the world. Nonetheless, this is a real risk of DLEK or 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, then the donor transplant can be replaced with another surgery and the vision ultimately restored.
Please contact me if you have ANY questions, and it is an honor for me to be your surgeon.
Mark A. Terry, M.D.
Director, Corneal Services
Devers Eye Institute
Portland, Oregon
FOR ANY QUESTIONS ABOUT THE SCHEDULING OF SURGERY, INSURANCE COVERAGE OR OTHER LOGISTICS, PLEASE CONTACT MY ADMINISTRATIVE ASSISTANT, Kaye Muffenbeyer, AT (503) 413-6223