Central versus paracentral endothelial cell density values in relation to duration of soft contact lens wear

Purpose. To assess whether the difference between midperipheral (paracentral) cell density (MPCD) and central cell density (CCD) values of the corneal endothelium could be related to the duration of soft contact lens wear. Methods. A cross-sectional, retrospective review of the endothelial images of 104 subjects who were between the ages of 20 and 41 years, were myopes (–0.725 to –7.625 spherical diopters), and had a history of 1 to 23 years of uninterrupted soft contact lens wear. Images were taken with a noncontact specular microscope (Topcon SP2000-P) at the central location and at a midperipheral location (i.e., 3 mm from the optical axis). The areas of 100 contiguous cells were measured with IMAGEnet software, and endothelial cell density values were calculated. Results. The mean CCD value was 2,747 cells/mm2, and the mean MPCD was 2,954 cells/mm2, with the net ratio of MPCD-to-CCD values being 1.0768:1 (P<0.001). The ratio of the MPCD:CCD values, expressed as a percentage, could be correlated to the years of soft contact lens wear, with a linear regression analysis indicating a modest but statistically significant effect (P = 0.008, r = 0.257). Conclusions. In morphometry of the corneal endothelium away from central sites, the history of contact lens wear must be considered.