Epidemiology of glaucoma in Japan--a nationwide glaucoma survey.

A population-based, collaborative glaucoma survey was conducted in seven regions throughout Japan, during the years of 1988 and 1989. The total number of subjects examined was 8,126 out of 16,078 residents aged 40 years or older, representing a participation rate of 50.54%. There were no significant differences in background factors between participants and randomly sampled nonparticipants. A mainstay of the screening consisted of tonometry and fundus photography with nonmydriatic camera, followed by automatic perimetry as a recall examination. Overall prevalences obtained were primary open-angle glaucoma (POAG) 0.58%, low-tension glaucoma (LTG) 2.04%, primary angle closure glaucoma (PACG) 0.34%, other types of glaucomas 0.60%, and ocular hypertension (OH) 1.37% at the time of screening. The very high prevalence of LTG and extremely low prevalence of OH in the Japanese might reflect a racial peculiarity in the age-specific trend of the intraocular pressure. The prevalence of PACG was found much higher in Japanese than in Caucasians, with a predilection for women. Racial peculiarities as revealed in this study were discussed, with particular reference to the refractive status in the Japanese that showed progressive decrease in myopia with age.