Topical MMC does not affect post-PRK endothelial cell density, study finds

Applying mitomycin-C topically to prevent the development of haze and regression after myopic PRK does not appear to significantly affect corneal endothelial cell density, according to a prospective study by researchers in Greece.

Vasilios F. Diakonis, MD, and colleagues at the University of Crete randomly assigned one eye of each of 15 patients to undergo PRK involving 0.02% MMC applied topically for 15 seconds. The fellow eye of each patient served as a control and was treated with epi-LASIK without MMC. All patients had low to moderate myopia.

Investigators performed confocal microscopy on all eyes preoperatively and at all follow-up exams out to 12 months postop. They also acquired three images of the endothelium in one eye of each patient preoperatively to evaluate the repeatability of endothelial cell density measurements and found a repeatability coefficient of 148 cells/mm², according to the study.

"Preoperative endothelial cell density was not significantly different between the two groups. Moreover, the effect of the treatment on the temporal variation of endothelial cell density was insignificant, whereas the differences between the preoperative and the postoperative endothelial cell densities reached statistical significance," the authors reported. "Nonetheless, inclusion of the repeatability of the instrument on the analysis diminished these significant differences."

Preoperatively, endothelial cell counts averaged 2,757 cells/mm² in the MMC-treated eyes and 2,769 cells/mm² in the control eyes.

In the MMC-treated eyes, endothelial cell counts averaged 2,736 cells/mm² at 1 month follow-up, 2,729 cells/mm² at 3 months, 2,716 cells/mm² at 6 months and 2,721 cells/mm² at 12 months.

In the control group, endothelial cell counts averaged 2,727 cells/mm² at 1 month follow-up, 2,741 cells/mm² at 3 months, 2,758 cells/mm² at 6 months and 2,760 cells/mm² at 12 months, according to the study.

"In the present study, the intraoperative use of MMC ... after PRK does not seem to have a different influence on the population of the endothelial cells as compared with the epi-LASIK technique," the authors said. "Nonetheless, endothelial cell density showed a decrease in both groups at 1 and 3 months after the surgery without considering the repeatability of endothelial cell count. However, this change of endothelial cell density seems to be explained by the repeatability of endothelial cell count."

The study is published in the July issue of the American Journal of Ophthalmology.