Corneal endothelial cell density and associated factors in a population-based study in Japan: the Kumejima study.

Purpose: To examine the distribution of corneal endothelial cell density (ECD) and relating factors in ophthalmologically normal Japanese in a population-based setting.

Design: Cross-sectional, population-based study.

Methods: All residents of Kumejima Island, Japan, located in southwestern Japan (eastern longitude 126 degrees 48' and northern latitude 26 degrees 20'), aged 40 years and older, were asked to undergo a comprehensive questionnaire and ocular examination, including noncontact specular microscopy of corneal endothelial cells.

Results: Of 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/mm(2), 2927 +/- 385 cells/mm(2), and 2959 +/- 389 cells/mm(2), 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/mm(2)/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/mm(2)/mm Hg (P < .001).

Conclusions: Mean ECD in ophthalmologically normal Japanese in Kumejima aged 40 years or older was 2943 cells/mm(2). Older age, male sex, higher intraocular pressure, and history of outdoor work were also identified as factors correlating with lower ECD.