Opening world's eyes to healing

Opening world's eyes to healing
Breakthrough study finds older corneas effective in transplants
Ann Geracimos THE WASHINGTON TIMES
Wednesday, July 9, 2008


Dr. Walter Stark inspects a donor cornea that he will transplant to a patient at the Johns Hopkins University Wilmer Eye Institute in Baltimore, Md.

The pool of donors for cornea transplants has been expanded by up to 30 percent, thanks to a federally funded study showing corneas from older donors can be used successfully. It was assumed previously - without any clinical proof - that younger donor tissue always was best.

The cornea, the protective transparent outer layer of the eye, is one of the most sensitive tissues in the body. If the tissue - which normally acts as a focusing instrument - is severely injured or diseased, the result can be blurred vision or even blindness. More than 10 million people around the world are blind because of diseased corneas, according to a June report in the journal Biotechnology Progress.

"A cornea is like the lens of a camera," says Dr. Walter Stark, director of the Stark-Mosher Center for Cataract and Corneal Diseases at Johns Hopkins University's Wilmer Eye Institute.

He is a member of a team that recently reported the breakthrough five-year study, which showed an 86 percent success rate with donor tissue coming from people between 66 and 72 years of age.

"We don't care so much about age as the quality of the cornea since older corneas are apt to lose a number of endothelial cells, and one might infer from that that younger would do better," Dr. Stark says. "Prior to this, we had trouble placing older corneas, so they often would not get used."

"Surgeons had this bias that was never substantiated on a scientific basis that they only want younger and younger corneas," says Dr. Edward J. Holland, director of cornea services at the Cincinnati Eye Institute and professor of ophthalmology at the University of Cincinnati. He was co-author of the study.

The new cutoff age remains arbitrary, he says, adding that the next challenge is persuading surgeons "to change their behavior."

"We've known for some time that every donor is an individual and that characteristics of a cornea at the time we evaluate it is the most important thing," says Jerry Cole, president and chief executive of the nonprofit Tissue Banks International, which collects, processes and distributes donor eye tissue. "What this study does is help us talk to the doctors that have been reluctant to use [older] tissue.

"Because it's nice to see when bandages come off patients, which is pretty much on the first day," Mr. Cole says. "If the surgery is successful, there is light perception they didn't have before. Often the first thing they see is the surgeon's face. Then they count fingers. There are lot of wonderful stories of people who lost vision when they were pregnant - due to a condition in their pregnancy - and then get to see their children for the first time."

He urges the public to visit Tissue Banks International Tissue Banks International for information on donation and how tissues are used.

The only reliable way to replace a cornea is through a transplant, which means removing the damaged tissue and inserting a healthy cornea from another human body, usually from a deceased donor through an eye bank.

"Corneas have the advantage of not having to be used immediately but can wait for 20 hours," Dr. Stark notes.

They are, of course, tested routinely to be certain they contain no transmittable diseases, among other criteria.

More than 36,000 Americans undergo this procedure every year, followed by treatment with steroidal eye drops to prevent tissue rejection. Transplants have been done at Hopkins on babies as young as 1 week old.

The cornea is the most frequently transplanted body part, but that does not mean there are enough available to meet needs, especially not with an aging population whose eyes are more prone to disease and injury than those of younger people.


Dr. Walter Stark performs a cornea transplant on a patient at the Johns Hopkins University Wilmer Eye Institute in Baltimore, Md. Monday, June 23, 2008.

Another matter influencing the availability of healthy corneas is the popularity of Lasik (laser-assisted in situ keratomileusis) surgical procedures designed to improve or correct a person's sight. These involve interfering with normal tissue. People who have had LASIK or cataract surgery should not be deterred from becoming donors, medical professionals say, because altered corneas are valuable in many ways, including for use in research and education.

Artificial corneas are being developed but aren't yet advanced enough for widespread use. Scientists at Stanford University are working on a version based on water-based synthetic gels that include collagen to help blend natural and artificial tissues to promote growth of an epithelial cell layer.

"We're a long way from having a clinical product," said Curtis W. Frank in answer to a telephone query about his group's progress.


Dr. Walter Stark of the Johns Hopkins University Wilmer Eye Institute uses a tool to cut and remove a patient's cornea, which will be replaced with a donor cornea.

"If you can get an artificial cornea that does not reject or melt, it would be fantastic," Dr. Stark says. "There is a shortage of corneas around the world, especially in the Third World, where an artificial cornea would be terrific for someone who is blind and cannot easily get a natural one."


After removing the center of a donor cornea to be transplanted to a patient, the remainder of the donor cornea is moved at the Johns Hopkins University Wilmer Eye Institute in Baltimore, Md.

These also are seen as a possible last resort for people who have repeatedly rejected natural corneas or who can't receive donated tissue because of severe eye diseases.

courtesy:

http://www.washingtontimes.com/news/2008/jul/09/opening-worlds-eyes-to-healing/