Corneal endothelial morphology is influenced by age and long term contact lens wear. The effect of refractive error, particularly high myopia has not been established. People with higher myopia are more likely to wear contact lenses and for longer, so age, contact lens wear, and degree of myopia may act independently or interact to change corneal endothelial morphology. We investigated the effects of age, race, years of contact lens wear, and degree of myopia on three key aspects of corneal endothelial morphology: endothelial cell density (ECD), coefficient of variation (CoV), and percentage of hexagonal cells (%Hex).

A total of 149 subjects with a broad variation in age (33.2 ± 11 years), refractive error (39.6% had myopia over –5.00 D), and contact lens history (13.4% had worn lenses for >20 years) were examined. One third were Asian. The Konan NonCon Robo 9000 specular microscope was used to capture corneal endothelial images from one eye of each subject. The images were analyzed with the KSS-300 center method. Multiple regression analysis was used to build models of endothelial cell density, coefficient of variation, and percentage of hexagonal cells as a function of age, race, refractive error (Rx), and contact lens wear (CLyears).

Age and race significantly affected endothelial cell density, but refractive error or years of contact lens wear did not (model: ECD = 3274 –; 12.7*Age + [164 if Asian]). Years of contact lens wear, age, and their interaction significantly affected the coefficient of variation (model: CoV = 24.3 + 0.72*CLyears + 0.18*Age – 0.011*interaction). Years of contact lens wear, age, and degree of myopia significantly affected the percentage of hexagonal cells (model: %Hex = 70 – 0.29*CLyears – 0.21*Age + 0.4*Rx).

The three key aspects of corneal endothelial morphology are not influenced by the same factors. In studying of the influence of drugs, disease, or treatment on the corneal endothelium, coefficient of variation and percentage of hexagonal cells might be more sensitive than endothelial cell density.