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.