Dr. Swan and Dr. Shin, our fellowship trained corneal surgeons, perform many different types of complex corneal surgical procedures. This information is provided to help you better understand DSAEK surgery and the basics of the post-operative follow up care involved. We believe that informed and educated patients are likely to have the best surgical experience.
The cornea is the front window of the eye. It has three layers - a surface epithelial layer (about 9% of the thickness of the entire cornea), a middle stromal layer (about 90% of the thickness of the entire cornea), and an inner endothelial layer (about 1% of the entire thickness of the cornea). Patients who have diseased or abnormally functioning endothelium (the inner layer) have reduced vision due to decreased corneal clarity and increased corneal thickness due to swelling of the corneal stromal (middle) layer. The corneal stroma is like a sponge. It tries to absorb fluid from the outer tear film and inner aqueous fluid. The primary purpose of the inner endothelial layer is to pump fluid out of the corneal stromal layer ensuring that it is thin and translucent. When the corneal endothelial layer is diseased or not functioning normally, the corneal stroma swells and is not clear; therefore, vision is poor.
Historically, the only way to replace the endothelial layer was to replace the entire central cornea – all three layers. This surgery is called a penetrating keratoplasty. While usually successful, this surgery involves placing 18 – 24 sutures into the cornea, which heals very slowly. The sutures must be removed slowly and often times the corneal transplant is not completely symmetrical; therefore, the patient’s vision recovers slowly and is often optically suboptimal due to astigmatism or induced nearsightedness or farsightedness. For this reason, many patients (as high as 30%) need to wear hard contact lenses to have optimal vision after penetrating keratoplasty.
Over the last several years, advances have been made in corneal surgery. For patients who have abnormal endothelial function, the best surgical procedure is now DSAEK – Descemet’s Stripping Automated Endothelial Keratoplasty. In this procedure, we are able to replace the abnormal inner endothelial layer without replacing the entire corneal thickness. The diseased inner layer is first removed through a small incision in the peripheral cornea (similar to the type of incision used in cataract surgery). A donor cornea from the eye bank is then prepared with a machine called a microkeratome, which was originally designed to make the anterior corneal flap used in LASIK. This machine sections a thin piece of tissue from the inside of the donor cornea, containing healthy endothelium that can function normally. The new endothelial layer is folded and placed into the eye through the same small incision in which the abnormal tissue was removed. An air bubble is then placed inside the eye, flattening the new endothelial layer against the swollen corneal stroma. As the new layer starts to function, it suctions to the stroma and begins to pump the fluid from the corneal stroma which returns to a thin, clear state thereby improving vision.
DSAEK is an outpatient procedure done with regional or local anesthesia and intravenous sedation. The surgery typically takes about 30-45 minutes to complete and there is no discomfort during the surgery. After the procedure, your eye will be patched overnight. It is very important to stay in a position with your face pointing up toward the sky as much as possible, for the first 24 hours after surgery. It is very important that you do not rub your eye at all for the first two weeks after surgery. We generally advise to discontinue eye rubbing as much as possible indefinitely after DSAEK.
Visual improvement after DSAEK is somewhat variable but the cornea generally begins to clear within 1 – 3 weeks and most patients are substantially better by 8 – 12 weeks, although, many people continue to gradually improve up to one year. The most common complication is dislocation of the thin transplanted tissue. This may require a brief procedure to reposition the graft with a new air bubble or, in rare cases; the transplanted tissue may need to be replaced entirely. Most patients have significantly improved vision after DSAEK. Frequently your glasses prescription will change after the surgery requiring a new pair of glasses 3 – 6 months post-op. Complete information regarding post-operative medications and follow up schedules will be provided to you after your surgery. If you have any unanswered questions, please ask any of our technicians, nurses, or doctors.
Thank you,
John L. Swan, II, M.D.
In C. Shin, M.D.