Eyeworld

EW CORNEA 122 March 2018 by Maxine Lipner EyeWorld Senior Contributing Writer "They needed that information for doing the procedure," Dr. Lass said. When a cornea was found to be eligible, this was then assigned to a patient, with half of the individuals receiving corneas that had been preserved for 7 days or less and the other half preserved for 8–14 days. In addition, the groups were subdi- vided into 0–4 days, 5–7 days, 8–11 days, and 12–14 days. Considering findings At the 3-year mark, results were promising. However, they were unable to prove non-inferiority as a whole of the tissue preserved for a longer time. To prove this, the con- fidence interval needed to be 4% or lower, but this was at 5.4%, Dr. Lass reported. However, the overall suc- cess rate was high in both groups at around 95% for the tissue preserved for the short time period and 92% for that in the longer preservation group. However, when the subgroup analysis was considered, it became clear that the failures in the longer preservation group were mainly coming from the oldest 12- to 14- day tissue. "In the paper we came out saying that there was no differ- ence up to 11 days, and even at 12 to 14 days, the success rate was at 89%, so it's still good," Dr. Lass said. Clinically speaking, this means that there is no difference up to 11 days, but if logistically you need to use tissue that has been preserved for 12–14 days, that's still good. For eye banks, this means more time to research the donors. "It's going to give them 3–4 more days to evaluate the tissue and distribute it both domestically and interna- tionally, and there will now be hard evidence that this is OK," Dr. Lass said. Investigators also determined that most of the failures were com- ing in the first 60 days after surgery. "Primary donor failure was defined as everything went fine at the time of surgery, but postop the cornea never cleared," he said, adding that in this initial time period there were 22 failures in the group preserved for longer and 11 in the shorter group. Investigators think that while this tissue may still appear good when considered with the Bias against long storage "There was a major prejudice against using tissue beyond 7 or 8 days even though the intermediate storage solution was approved by the FDA to go out to 14 days," Dr. Lass said. "Also, we were aware that the eye banks, because of this prejudice, were shipping the tissue out of the country and successfully using it internationally," Dr. Lass said. Sur- geons in the U.S. were reluctant to use tissue that had been preserved longer, based mainly on what they had been taught. "They learned to do this in their fellowships, but there was no solid evidence for do- ing this," he said. Included in the study were 1,330 eyes, with about an equal dis- tribution between both groups, Dr. Lass noted, adding that they chose DSAEK as the procedure with which to test preservation time because this is currently the most common keratoplasty technique in use. In this masked study, the only thing surgeons knew about the donor was the thickness of the cor- neal tissue after lamellar dissection. preserved for a much shorter period, according to Jonathan Lass, MD, Case Western Reserve, University Hospitals Eye Institute, Cleveland. This study, published in JAMA Ophthalmology, grew out of an ear- lier donor graft study, with inves- tigators deciding that the issue of cornea preservation would be the next major question with regard to the donor pool. 1 Studying graft success in tissue that was preserved up to 14 days J ust how long can corneal tissue be kept and still remain viable for use? In- vestigators determined that tissue stored for up to 11 days had success rates equal to tissue The long and short of corneal preservation times Research highlight Eyes such as this one that have received corneal grafts can find success even when tissue has been stored for up to 11 days. Source: George Rosenwasser, MD Donor tissue and donor age Jonathan Lass, MD, discusses results from a study looking at graft survival and donor age. EWReplay.org

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