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Wednesday, October 27, 2021

Five-year study confirms older cornea tissue acceptable for transplant

Patients undergoing cornea transplant surgery can now have confidence in using cornea tissue from donors over 75 years of age, thanks to a recent study published by UC Davis professor and chair of the department of ophthalmology, Dr. Mark J Mannis.

Before Mannis’ five-year-long national study of cornea transplant patients, doctors were hesitant to use old cornea tissue for fear of worn down cells. Now, after finding that the success rate for older cornea tissue is the same as that of younger cornea tissue, the donor pool has increased by approximately 30 percent.

Corneas, located in the front of the eye over the iris, protect the eye and focus light entering the eye. Cornea injury, the number two cause of blindness behind macular degeneration, is caused by a range of disorders and accidents, from the herpes virus to a simple chemical burn.

“It has long been believed both by patients and doctors that elders are not suitable donors,” Mannis said. “Most of our donors are in the older age group, so this will have a tremendous impact on the tissue available for transplant.”

The study, funded by the National Eye Institute, followed cornea transplant patients from 43 eye banks across America. The donors’ ages ranged from 12 to 80 years old. The findings revealed that after five years, there was virtually no difference between the recovery of the patients who received corneas from donors 12 to 65 years old and donors 66 to 75 years old.

“He realized that the [study would be] so big and would require so many patients, that he set up a multi-center trial where numerous surgeons would follow their patients’ cornea recovery,” said Dr. Ivan R. Schwab, professor of ophthalmology and member of the donor study group.

A second premise the study confirmed was that all patients lost a number of endothelial cells five years after the transplant, regardless of the age of the donor. The cells are located under the surface of the eye and allow the cornea to remain clear.

“Now that we can look at it nationwide, we can tell that [endothelial cell loss] is a consequence of having the surgery,” Schwab said.

The findings are also important because of new regulations placed by the U.S. Food and Drug Administration in June of 2007 that require extra screening for contagious diseases, registration of eye banks, more detailed records and labels, and stricter quarantine procedures. The regulations limit the number of people qualified to donate, so Mannis’ study would then increase the donor pool formally diminished by the regulations.

“All eye banks have a mission to restore eyesight and they don’t want to have to use tissue that would harm their patients,” said Patricia Aiken-O’Neill, President and CEO of the Eye Bank Association of America. “It will reassure the receiving surgeon that age is not a factor.”

According to the association, more than 40,000 corneal transplants are performed in the United States each year. Without these transplants, many cornea-damaged patients would chronically endure faulty vision, eye-aches, or blindness.

Tim Noyce, a computer game engineer from St. Paul, Minn., received a cornea transplant for a painful vision disorder called keratoconus. He said that although the procedure was uncomfortable and intensive, after recovery his vision was better and he experienced less pain.

“The visual acuity out of that eye at this pointis still pretty blurry without any correction,” Noyce said in an online interview. “At the last check, my corrected vision was 20/25, which is much better than it would have been otherwise.”

Noyce and other cornea transplant patients have attested to the success of the operation. With research performed by Mannis and the 105 other surgeons across the country, doctors will now have a restored confidence in the tissue they use, Schwab said.

“Dr. Mannis was the key player in this study,” Schwab said. “He deserves the recognition for coming up with the idea and for pushing it.”

LAUREN STEUSSY can be reached at campus@californiaaggie.com.XXX

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