Newer Technique for Corneal Transplant Brings Rejection Below 1%

January 12, 2012

By Anne Harding

NEW YORK (Reuters Health) Jan 11 - Corneal transplants using only the endothelial layer sharply reduce the risk of transplant rejection, according to a new comparative case series.

The findings mean it might be possible to use eyedrops with lower doses of steroids after the surgery, which could lead to fewer potentially vision-damaging side effects such as increases in intraocular pressure, co-author Dr. Marianne O. Price, of the Cornea Research Foundation of America in Indianapolis, told Reuters Health.

The technique, Descemet's membrane endothelial keratoplasty (DMEK), is an advance over Descemet's stripping endothelial keratoplasty (DSEK), which involves transplanting the endothelial layer with some stroma attached through a small incision.

DSEK in turn was an improvement on penetrating keratoplasty (PK), a century-old approach in which the entire corneal thickness including epithelium, stroma, and endothelium is transplanted.

The newest of the surgeries, DMEK, has already been shown to produce better visual outcomes, with patients achieving a line or more of better vision on an eye chart, Dr. Price said in an interview.

In the current study, published online January 4 in Ophthalmology, she and her colleagues investigated the risk of rejection episodes with the three transplant techniques by comparing outcomes in 141 eyes treated with DMEK; 598 eyes treated with DSEK; and 30 eyes treated with PK.

All patients were treated at the same center, using the same anti-rejection regimen. Ninety percent of the transplants were done for Fuch's dystrophy. The median follow-up after DMEK was 13 months.

The proportion of patients who experienced a rejection episode was 0.7% with DMEK, 9% with DSEK, and 17% with PK, Dr. Price and her team found.

On Kaplan-Meier analysis, the probability of rejection at one at two years, respectively, was 1% and 1% in the DMEK group, 8% and 12% in the DSEK group, and 14% and 18% in PK group.

Overall, the risk of a rejection episode was 20-fold lower after DMEK than after PK, and 15-fold lower after DMEK than after DSEK.

As a result of these findings, the Cornea Research Foundation is sponsoring an international trial to test the safety and efficacy of lower-strength corticosteroid eyedrops after DMEK.

Dr. Price told Reuters Health that the drops increase intraocular pressure in about a third of patients at her center. Some of these patients, she added, get into a "really unfortunate cycle" in which steroid doses must be reduced to reduce intraocular pressure, and then increased again to treat and prevent rejection.

"We're hopeful that by having a procedure that has such a low rejection rate, that we can use a more innocuous eyedrop and prevent serious side effects from happening in many people," she said.

While DSEK is now widely used, only a few surgeons worldwide are doing high volumes of DMEK procedures, and many surgeons don't use the procedure yet, Dr. Price said. The newer technique is more technically challenging, she noted.

"Definitely it is more difficult to prepare the single-cell layer and to get it to unroll and adhere to the back of the patient's cornea in the proper orientation," she added. "That's one of the reasons the procedure is catching on somewhat slowly."

Dr. Price said she hopes that news of the much lower rejection rate with DMEK, and the potential for reduced steroid use, will make for a "tipping point" that leads to wider adoption of the procedure.

SOURCE: http://bit.ly/zojMiK

Ophthalmology 2012.

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