An observational cross-sectional study on the corneal endothelium of medium-term rigid gas permeable contact lens wearers.

Purpose: To assess if polymegethism and pleomorphism were evident in corneal endothelium after medium-term rigid gas permeable (RGP) contact lens wear.

Methods: In a cross-sectional observational study over 12 years, single images of the central region of the corneal endothelium of one eye of 46 subjects were taken with a non-contact specular microscope, along with a measure of central corneal thickness (CCT). The images were printed onto A3-sized paper and 100 cells/image measured by planimetry.

Results: Subjects aged between 20 and 32 years, with an average cumulative RGP wear of 6.0+/- 1.6 years (range 3-9 years) were assessed; 26 of the subjects were Caucasian and 20 were Asian. The mean CCT was 0.515+/- 0.027mm. The group cell area value was 401+/- 42 sq micron to give an estimated endothelial cell density (ECD) of 2520+/- 273 cells/sq mm. As compared to a historical database, most endothelia (37/46) showed some changes with the mean coefficient of variation on cell area (COV) being 36.7+/- 8.0% and the percentage of 6-sided (HEX) being 51.8+/- 8.8%. There were modest correlations between years of RGP wear and both COV (p=0.009, r spearman=0.424) and HEX (p=0.025, r spearman=-0.291), but not for ECD or CCT.

Conclusions: Corneal endothelial polymegethism appears to be a commonplace consequence of RGP lens wear with the magnitude of the change being related to the cumulative duration of the lens wear.