August 2008

 

OPHTHALMOLOGY NEWS

 

Cornea banks to prosper from study


By Enette Ngoei EyeWorld Staff Writer 

 

 

New research is expected to lead to the growth of available corneas for transplants

Folded donor cornea being inserted

Donor cornea post-DSAEK Source: Mark Gorovoy, M.D.

The growing need for corneal transplants may soon be met by an expanded pool of available donor corneas. That’s because a five- year prospective study has shown that corneal transplant tissues from older donors aged 66 to 75 years performed with the same success rate as tissue from donors aged 12 to 65 years. “The literature in ophthalmology on the suitability of older donors has not been very definitive but there’s been a general bias against the use of older donors both by physicians and by patients,” said the study’s co-principle investigator, Mark J. Mannis, M.D., professor and chair, Department of Ophthalmology and Vision Science, University of California, Davis.

“Those of us who’ve been doing transplants for many years, the more experienced surgeons, have recognized for a long time that older tissue appears to work as well as younger tissue but there’s been reluctance on the part of many young surgeons to accept older tissue thinking that younger tissue has got to be better,” he said.

Proving that older donor corneas are equal to younger donor corneas in their efficacy would potentially enlarge the donor pool by as much as 20 to 35 percent since many eye banks currently only set the donor age cut-off at 65 years old, he said.

The bigger pool would better serve the American public as well as the international community where the need for tissue to cure corneal blindness is much greater than in the United States, Dr. Mannis said.

The largest longitudinal prospective study in corneal transplant patients ever performed, the research followed 1101 patients who were enrolled by 105 surgeons at 80 sites across the United States. Donor corneas were provided by 43 participating eye banks. The success rate in both older donor corneal transplants and younger donor corneal transplants was found to be 85%. The transplant was determined a failure if a repeat corneal transplant was required or if the cornea was cloudy for at least three months.

Though just recently completed and published in the April issue of Ophthalmology, Dr. Mannis said the idea of the study was initiated over 10 years ago when Dr. Mannis gave an address to the Eye Bank Association of America discussing the theory of using older cornea donors. At that time, Dr. Mannis and Edward J. Holland, M.D., professor of ophthalmology, University of Cincinnati, and director, Cornea Service at the Cincinnati Eye Institute, the study’s other principle investigator, recognized that there was going to be an increasing demand for corneal tissue on a national and international basis. The potential supply of donors was decreasing because of the increasing government restrictions on testing. There was also the increasing prevalence of refractive surgery, which disqualifies corneas for donation. More recently, the U.S. Food and Drug Administration (FDA) implemented, in June 2007, regulations for additional screening and testing of potential donors for contagious diseases, registration of eye banks, more detailed records and labels and stricter quarantine procedures, further reducing the potential availability of corneal tissue.

According to an NIH press release, Paul A Sieving, M.D., Ph.D., director of the National Eye Institute, which provided funding for the study, said the new research has come at an opportune time. “The pressure on eye banks to provide corneas is increasing. The results of this study will expand the available donor pool and should persuade surgeons to use corneas from older donors,” he said in the release.

Dr. Mannis said the research team is now seeking funding to follow patients for an additional five years to see if the 10-year follow-up of these patients will validate these conclusions.

He said that he anticipates that the 10-year findings will indeed support these findings.

Dr. Mannis said his research team expects that the study will directly lead to changes in FDA guidelines for eye banking as well as the policy of the member eye banks of the Eye Bank Association of America, thereby directly broadening the availability of the pool of tissue available for transplantation. Together with Dr. Holland, Dr. Mannis approached the Jaeb Center for Health Research in Tampa, Fla., where the study was based about doing the study. Support and funding for the research was received from the National Eye Institute and the Cornea Society and the Eye Bank Association of America along with several individual eye banks.

Editors’ note: Dr. Mannis does not have any financial interests related to this article.

Contact information:
Mannis: 916-734-6957, mjmannis@ucdavis.edu

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