Published: Apr. 20, 2006
Updated: Apr. 21, 2006
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By Duke Medicine News and Communications
DURHAM, N.C. -- A new technique being used in some types of cornea transplants means a shorter recovery time for patients and may lead to even better vision after surgery. The advance could make it possible for eye specialists to offer cornea transplants to visually impaired patients in Third World countries and other areas where such procedures have previously been impractical, according to researchers at Duke University Eye Center.
The technique, known as Descemet's Stripping Endothelial Keratoplasty (DSEK), allows surgeons to remove a much smaller portion of the patient's cornea compared with older methods of transplantation. Standard human cornea transplants involve removal of the full thickness of the patient's cornea and replacement with full thickness donor tissue. In the newer method, surgeons remove only the diseased layer of cells at the back of the cornea and replace it with a similar amount of donor tissue. Doing so helps to retain the structural integrity and mechanical strength of the eye, and typically means a shorter recovery period for the patient.
"Although successful cornea transplant surgeries are considered routine even with older surgical techniques, our patients experience a more rapid recovery of their vision after the new DSEK procedure," said Alan Carlson, M.D., ophthalmologist and chief of the cornea service at Duke. "With the older, full thickness transplant techniques, the eye is never structurally as strong as it was before the surgery. This newer way of performing cornea transplants is a quantum leap. To me, this is as big a deal as the development of arthroscopic surgery was to knee repair or laparoscopic surgery for the abdomen."
Approximately 35,000 cornea transplants are performed each year in the U.S. Use of the DSEK technique is limited to patients with damage to the endothelial area of the cornea, which accounts for about two-thirds of these cases, Carlson said.
The cornea is comprised of several layers, including Descemet's membrane and the endothelium. Descemet's membrane is a thin layer that supports endothelial cells on the back of the cornea. The endothelium, comprised of endothelial cells, is the delicate back portion of the cornea that manages fluid content within the corneal structure.
In a DSEK procedure, the surgeon removes the inner-most layer of the endothelium along with Descemet's membrane. That section is then replaced with a delicate healthy layer of donated human cornea tissue. Using specialized tools, the new tissue is positioned into the cornea. The new tissue heals without sutures.
"There isn't anything more exciting to me as a surgeon than DSEK right now," Carlson said. "The shorter recovery time and the retained integrity of the eye mean that my patients will be able to live a fuller life and resume regular activities with much fewer worries than my patients from even a year ago."
The most common reasons people need cornea transplants are Fuchs' dystrophy, traumatic injury to the eye area, previous eye surgery and diseases that affect the endothelium. Diseases and injuries that destroy the endothelium can lead to blindness, at which time a cornea transplant is the only treatment that can restore vision.
According to Carlson, a patient can regain useful vision within two weeks and driving vision within two to three months following the DSEK procedure, as opposed to six and 12 months, respectively, with the older method.
The biggest risks following a full cornea transplant include tissue rejection, glaucoma and slow healing at the incision site. Another major problem can occur when a patient falls or otherwise accidentally injures the eye with the transplanted cornea. Since a full cornea transplant weakens the eye, falling after surgery or being accidentally poked in the eye can seriously damage the transplant and surrounding tissue. With structural integrity of the eye maintained with the DSEK technique, such injuries are less of a problem, hence reduced fear on the part of a recovering patient, Carlson said.
The DSEK technique is currently available in limited areas throughout the U.S. and is growing in popularity.
The procedure has even greater potential in Third-World countries where cornea diseases are prevalent. There, cornea transplantation is rarely an option due to the specialized care that has been needed following full-thickness cornea transplants. Infections, donor tissue rejection and problems with hygiene are problems inherent to transplantation in all parts of the world, but in the Third World such transplants are largely impractical due to a shortage of eye specialists and other physicians, according to Carlson.
"It will be incredible to take this technique to other countries where so many people suffer from corneal blindness," Carlson said. "In many places in the world, if a person cannot see, they won't be able to survive. I believe this advance will really help change the human condition in places where this type of hope is needed."