Corneal Endothelial Cell Density and Associated Factors in a Population-Based Study in Japan: The Kumejima Study

PurposeTo examine the distribution of corneal endothelial cell density (ECD) and relating factors in ophthalmologically normal Japanese in a population-based setting.DesignCross-sectional, population-based study.MethodsAll residents of Kumejima Island, Japan, located in southwestern Japan (eastern longitude 126° 48′ and northern latitude 26° 20′), aged 40 years and older, were asked to undergo a comprehensive questionnaire and ocular examination, including noncontact specular microscopy of corneal endothelial cells.ResultsOf the 4632 residents, 3762 (81.2%) underwent the examination. The mean ECD among all ophthalmologically normal participants (n = 2602), men (n = 1329), and women (n = 1273) was 2943 ± 387 cells/mm2, 2927 ± 385 cells/mm2, and 2959 ± 389 cells/mm2, respectively, with a significant inter-sex difference after adjusting for age (P = .001). Mean ECD was significantly lower in subgroups with a history of outdoor work compared to corresponding subgroups after adjusting for age and sex (P = .034). Linear regression analyses with an adjustment for age and/or sex showed that age was significantly negatively correlated with ECD with a slope of −7.43/mm2/year (P < .001), indicating a cell loss rate of 0.25% per year of age. Higher intraocular pressure was significantly correlated with lower ECD, with a slope of −9.87/mm2/mm Hg (P < .001).ConclusionsMean ECD in ophthalmologically normal Japanese in Kumejima aged 40 years or older was 2943 cells/mm2. Older age, male sex, higher intraocular pressure, and history of outdoor work were also identified as factors correlating with lower ECD.