Descemet's Stripping Automated Endothelial Keratoplasty
Fuch's Dystrophy and bullous keratopathy (corneal edema) are conditions in which the cornea (the front part of the eye) is cloudy. Patients with this condition may benefit from a corneal transplant. This surgery involves replacing the cornea with a cornea that has been donated by someone who has died (the donor cornea). The donor cornea to be used for your transplant will be provided by a certified Eye Bank. A patient with Fuchs Dystrophy or Corneal edema is likely a candidate for Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK). In Fuchs Dystrophy, the endothelium layer of the cornea is failing and is causing the cornea to become swollen and cloudy. The endothelium is the layer of cells on the inside surface of your cornea. It is this layer that needs to be replaced. Until recently, the only way to replace that layer of cells was with a full thickness corneal transplant. Over the last several years, a technique has been developed to replace only the back layer of the cornea (DSAEK) instead of replacing the entire full thickness cornea (Penetrating Keratoplasty). This new transplant technique has been shown to provide good vision and to have many potential advantages over full thickness transplants, including earlier return of vision, less refractive errors, fewer serious complications, and a more stable eye.
DSAEK surgery is scheduled in coordination with the eye bank and the Surgery Center operating room. It is performed as an outpatient surgery under local anesthesia. During the surgery, a small incision with a length of only 5 mm (less than ¼ inch) is made in the sclera (the white part of the eye), and the back portion of the diseased cornea (Descemet's membrane and endothelium) is removed. The healthy back portion of the donor cornea is then inserted through the incision and positioned on the back surface of the cornea to replace the diseased tissue which was removed. The small incision is then closed with three small sutures and the procedure is completed. The surgical procedure takes about one hour to perform.
Risks that are unique to Descemet's Stripping Automated Endothelial Keratoplasty surgery (DSAEK) compared with full-thickness corneal transplant surgery (Penetrating Keratoplasty) include:
1) Dislocation of the partial thickness donor corneal transplant tissue within the eye can occasionally occur. This requires another small procedure in the office to put the tissue back into the proper position. Dislocated tissue is usually noted on the first day after surgery, and the repositioning procedure is generally performed within the next week. If the tissue could not be re-positioned, a full thickness corneal transplant (Penetrating Keratoplasty) may be necessary.
2) Healing occurs at the interface between your tissue and the new donor tissue. This occurs both in the periphery (outside the line of sight) and the central, pupillary region (over the line of sight). If haze or clouding developed in this central area, the vision could be decreased from its full potential, and a full thickness transplant (Penetrating Keratoplasty) may be necessary.
3) There is the possibility that the endothelial cells of the donor tissue could fail and the cornea become cloudy. There may be a higher probability of this failure with DSAEK than with Penetrating Keratoplasty. If the cornea becomes cloudy, the DSAEK may need to be repeated, or a full thickness corneal transplant (Penetrating Keratoplasty) may be required to restore the vision.
4) DSAEK is a relatively a new procedure and long term results are not known. Although we have tried to list all possible risks and discomforts, there may be others that we do not know about at this time.
Possible direct benefits unique to Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) compared with full thickness corneal transplant surgery (Penetrating Keratoplasty) include:
1) Patients who undergo full thickness corneal transplants usually must wait 6 months or more before their vision is restored and stable enough to obtain new glasses. With DSAEK, a smoother surface for focusing usually results in improved vision much sooner - generally three months.
2) Full thickness corneal transplant surgery results in a change in the corneal curvature. Since the power of one's glasses is partially related to this curvature, strong glasses are often required to correct large amounts of nearsightedness, farsightedness and astigmatism. Sometimes, a rigid contact lens or even surgery is required to correct the astigmatism. In contrast, after DSAEK, the corneal surface remains smooth and relatively unchanged from the curvature before transplant surgery. Therefore, there is much less chance of requiring strong or thick glasses after DSAEK compared to full thickness corneal transplant surgery.
3) Patients who undergo full thickness transplant surgery often have problems with glare and distortions due to surface irregularity from the large corneal wound and many corneal sutures. Patients who have DSAEK have been shown to have a much smoother corneal surface. This occurs because the natural surface of the cornea is not replaced so the focusing power of the cornea remains more natural than with a full thickness corneal transplant. This smoother surface would be expected to result in better quality of vision and less distortions and glare.
4) Patients who have full thickness transplant surgery require 16 sutures or more, some of which may be left in for several years. These sutures can lead to problems such as surface irregularity, discomfort, blood vessel formation, infection, and corneal wound problems. In contrast, the three tiny sutures that are used in DSAEK are not irritating and usually do not cause problems.
5) Patients who undergo full thickness transplant surgery are much more susceptible to wound rupture and serious injury from any kind of trauma, since the long, full thickness corneal incision never regains normal strength. With DSAEK, because there is only a small peripheral incision, the eye should be much stronger and less susceptible to serious injury from trauma.
6) In full thickness transplant surgery, all the corneal nerves are cut. While the nerves eventually grow back during the postoperative period, this sometimes leads to surface problems which can result in irritation, blurred vision, erosions, or even infection. In DSAEK, only a very small peripheral incision is made. Therefore, the corneal nerves remain largely intact, and surface problems are not expected to occur.
In general, DSAEK surgery is a new transplant technique has been shown to provide good vision and to have many potential advantages over full thickness transplants, including earlier return of vision, less refractive errors, fewer serious complications, and a more stable eye. We hope this information is helpful.