Study indicates need for new standards and training for cornea transplants

Improving the training and standardizing the procedures used by the nation's eye banks to assess corneal cells may help to select corneas with optimal health for transplantation, according to new study led by Jonathan H. Lass, MD, principal investigator of the study and chairman of the Department of Ophthalmology at University Hospitals of Cleveland and Case Western Reserve University School of Medicine.

This study is reported in the current (March) issue of Ophthalmology, the journal of the American Academy of Ophthalmology. The National Eye Institute and the Eye Bank Association of America funded this research.

The study, which is part of a larger Cornea Donor Study of 1,101 patients, was designed to evaluate the quality of the microscope images of the donor cornea and the number of donor cornea's endothelial cells because those parameters may help to determine the long-term (at least ten years) survival of a transplanted cornea. (Endothelial cells form the back cell layer of the cornea and keep the cornea clear.)

When researchers measured the image quality and density of endothelial cells in the cornea, they were performing the same type of assessment that eye banks perform to ascertain whether a cornea is healthy enough for a transplant.

"Our results found that, over all, the current system for assessing quality and density of cells is good in the nation's eye banks," Dr. Lass says. "But there is room for improvement in some eye banks' assessment procedures, both in terms of enhancing image quality of the microscope image of the corneal cells and improving the accuracy of counting cells, parameters used to assess the health of a cornea."

More than 35,000 corneal transplants are performed annually in the United States, most of them on patients who undergo a corneal transplant because they have swelling due to cataract surgery or they have Fuchs' Dystrophy, a condition in which the endothelial cells deteriorate.

Eye banks play a crucial role in cornea transplantation. According to the Eye Bank Association of America, eye banks supplied the corneal tissue for 32,144 transplants in 2003.

"Often, the eye bank cell counts were off by more than 10 percent," Dr. Lass says. "We believe these data will trigger the development of new methods, improved training and universal standards to ensure that healthier corneas are being transplanted."