Corneal transplant: recipients at risk

Studying possible recipient-related factors for failure

Some study patients undergoing tranplant had Fuchs dystrophy (shown here) Source: Ricardo Amin, M.D.

For patients undergoing corneal transplant, risk of graft failure jumps significantly for those with corneal edema, found Alan Sugar, M.D., professor of ophthalmology, Kellogg Eye Center, University of Michigan, Ann Arbor, Mich. Study results published in the June 2009 issue of Ophthalmology showed a four-fold increase in graft failure for those with aphakic corneal edema compared with Fuchs’ dystrophy patients.
The prospective, randomized study was initially launched to look at the effect of aging on corneal transplants. “The purpose was to look at corneas from donors under and over 65 and see the outcomes,” Dr. Sugar said. “The current sub-studies are looking at other data from that same population.”
While in the initial study the focus was on the donors, in this sub-study investigators were keyed in on what role recipient factors might play in graft failure. In the study, donor corneas were randomly given to patients with both investigators and doctors masked to recipient factors such as disease history and donor factors such as age. Participants were followed for up to 5 years.

Considering edema risk

Included in this recent secondary analysis were 1,090 subjects who were undergoing corneal transplant for either Fuchs’ dystrophy or pseudophakic corneal edema. About two-thirds of those included had Fuchs’ dystrophy and one-third had corneal edema. “The main outcome was transplant failure, and so we wanted to look more carefully at failure,” Dr. Sugar said. “There are a lot of different ways of looking at this, and in this particular paper we were looking at recipient factors.”
In reviewing the data, investigators determined that patients with Fuchs’ dystrophy did better than those with aphakic corneal edema. “There was a 27% failure for aphakic and pseudophakic corneal edema and just 7% for those with Fuchs’ dystrophy,” Dr. Sugar said. “So there was a substantial difference.”
Dr. Sugar thinks that this difference can be traced back to the fundamental treatment facts. “Patients with Fuchs’ dystrophy have abnormal corneal endothelium, and we replace that by giving them a new cornea,” he said. “Patients who have pseudophakic corneal edema, however, are a very small minority of patients who have had cataract extraction, and in some way the surgery and/or the presence of the intraocular lens does something bad to the cornea.” The problem is that whatever was irritating the eye may remain and plague the new cornea as well. “In one group, we get rid of the disease and in the other group we may just be getting rid of the effect of the disease,” Dr. Sugar said. “Something ongoing can do further damage.”

Other risk factors

Another significant outcome centered on the severity of the recipients’ glaucoma history.
Investigators found a graded effect with graft failure substantially increased in those who had undergone prior glaucoma surgery and who had also taken glaucoma medication. “If you call the people without glaucoma one, the hazard ratio is about two for medications only, about three for surgery only, and about seven for medications and surgery,” Dr. Sugar said.
Also found to be significant was the recipient’s race. “The number of non-whites was too small to distinguish Hispanic non-whites and African-American non-whites, so it wasn’t divided by race, but it was found to be statistically significant that non-whites didn’t do as well as whites,” Dr. Sugar said. “That has also been shown in the past.”
Graft failure rate, however, was not strongly affected by age, gender, graft size, or a history of diabetes or smoking. Dr. Sugar hopes that the outcomes will spur further research. He also hopes that practitioners will come away from the study with the sense that there are differences between recipients. “The take-home message from the study is that donor age doesn’t seem to make a difference, and we can use corneas that are much older than we used to think was the limit,” Dr. Sugar said. “The secondary implications are that perhaps we should be more cautious in prognosticating for patients with pseudophakic corneal edema.”
Overall, Dr. Sugar sees the study as having lasting importance. “We think that it does have implications for corneal transplant practice and for eye-banking practices,” he said. “We are currently at seven to eight years of follow up of these groups and will be analyzing the data at 10 years—hopefully then we’ll be able to get better answers.”

Editors’ note: Dr. Sugar has no financial interests related to his comments.

Contact information

Sugar: asugar@umich.edu