Infection after cornea transplants higher under certain circumstances

By Glenna Picton

Cornea donors who had cancer or were in the hospital when they died present a slight risk of infection to those who receive a corneal transplant, said epidemiologists at Baylor College of Medicine.

The chance of infection after corneal transplant is generally quite small but still exists, said Kirk Wilhelmus, M.D., professor of ophthalmology at BCM and a co-author of a report that appeared in the Archives of Ophthalmology. That study of 10 years of corneal transplant surgery showed that an opportunity for transmitting an infection was slightly higher when the donor died of cancer or while very ill in the hospital.

However, the risk of infection is very small. In the decade the study covered, 340,174 corneas were made available for transplant in the United States. Only 162 post-transplant infections were reported during this period.

Thorough evaluation critical

"We found that thorough evaluation of the donor was important to assure the safety of corneal transplants," said Wilhelmus. "Donors who were seriously ill can be more likely to harbor bacteria or fungi that could lead to infection after surgery."

"Eye banks do a fantastic job of preventing infectious microbes from being transmitted between the donor and the patient," said Wilhelmus. "But some microorganisms can elude antimicrobials during the preservation process."

Infection after this procedure can lead to vision loss and possibly blindness in the eye receiving the transplant, said Wilhelmus. The Eye Bank Association of America monitors corneal transplants for adverse reactions that may be attributed to donor eye tissue.

Approximately 33,000 people in the U.S. undergo this procedure each year, which involves the removal of the central part of the cornea (the clear front window of the eye) and its replacement with a cornea from a donor.

Preventative steps

"A lot of effort goes into preventative steps," said Wilhelmus. The donation procedure, said Wilhelmus, includes application of antiseptic, use of sterilized materials and placement of eye tissue in solution with antibiotics.

"We decided to study if there are additional opportunities to enhance these measures," said Wilhelmus. In the study, the team of researchers unveiled some key differences in some donors that may increase the opportunity for transmitting infection. The researchers found that patient age also played a role in susceptibility to infection.

"The risk of infection was higher in older patients," said Wilhelmus. "We found that patients getting an infection were, on average, older than those without." Previous studies done with cataract surgery patients confirmed the same finding.

"And the longer the eye tissue remained in storage, the slightly higher the chance of transmitting infection became," said Wilhelmus. He said tissue usually remains in the eye bank as the donor blood undergoes tests for various viral diseases.

Research ongoing

Wilhelmus said research in eye banking is ongoing and that patients contemplating surgery should be assured that screening efforts continue to improve. "This study confirms that corneal surgery is safe," said Wilhelmus. "Eye banks are very diligent in efficiently evaluating and distributing donated eye tissues."

March is National Eye Donor Month, an occasion to focus on the efforts of eye banks and new developments in corneal surgery.

Other contributors to this study include Sohela Hassan from BCM, Patricia Dahl from the Eye-Bank for Sight Restoration, Inc., Gregory Davis from the Donor Network of Arizona, Russell Roberts from the Lions Eye Bank of Texas, Kevin Ross from the Midwest Eye-Bank, Bruce Varnum from the Georgia Eye Bank and members of the Eye Bank Association of America.

This study was supported by the National Eye Institute, the Eye Bank Association of America, Research to Prevent Blindness, Inc. and the Sid W. Richardson Foundation.