Endothelial cell loss during pterygium surgery: importance of timing of mitomycin C application.

PURPOSE: To determine if the timing of mitomycin C (MMC) application during pterygium surgery affects endothelial cell loss.

METHODS

A retrospective, nonrandomized, case-series design was used. The study group included 40 patients who underwent pterygium surgery with the bare sclera technique. MMC 0.02% was applied intraoperatively for 5 minutes, either before (16 patients) or after (24 patients) excision of the head of the pterygium. Endothelial images were acquired at the center of the cornea with a specular microscope before surgery and at 3 intervals during follow-up (average of 3 measurements each). Differences in cell loss from baseline were analyzed by paired t test.

RESULTS

In the group in which MMC was applied post excision, mean preoperative endothelial cell count was 2254 +/- 128 cells per square millimeter. Mean postoperative values were 1775 +/- 63 cells per square millimeter at 1 week (percentage cell loss, 21.25% +/- 2.8%), 1707 +/- 41 cells per square millimeter at 1 month (24.26% +/- 1.8%), and 1780 +/- 72 cells per square millimeter at 3 months (21.05% +/- 3.2%). The difference in cell count from the preoperative value was significant at all time points (P < 0.02). In the group in which MMC was applied before excision, mean preoperative endothelial cell count was 2352 +/- 118 cells per square millimeter, and mean postoperative values were 2345 +/- 120 cell per square millimeter at 1 week, 2260 +/- 162 cells per square millimeter at 1 month, and 2230 +/- 144 cells per square millimeter at 3 months. No endothelial cell loss was documented in this group.

CONCLUSION

The endothelial cell loss associated with the use of MMC during pterygium surgery might be avoided by applying MMC before excision of the pterygium head, so that it does not come into contact with the corneal surface.