Prevalence of AMD in the Japanese: The Nagahama Study

Abstract

Purpose: : Although some small Japanese cohorts have been studied, detailed characteristics of AMD in a large Japanese cohort have not been reported. Knowing characteristics of early AMD can help prevent development of late AMD. This study aimed to determine age-related macular degeneration (AMD) prevalence and characteristics in the Japanese.

Methods: : To evaluate prevalence data and AMD characteristics for the Japanese with regard to age, gender, spherical equivalent, and axial length, we graded fundus photographs of both eyes of participants involved prior to 2009 in the Nagahama Cohort Project for community-based genome/epidemiology research; this project collects biological data, including that on blood/serum, urine, and DNA analysis, and physical/physiological tests, of participants (age ≥ 30 years) living in Nagahama City. From 2009 to 2010, 5760 healthy Japanese indivisuals participated in the Nagahama study. We studied in 3281 subjects with the ages of 50 or older who had a nonmydriatic fundus photograph of both eyes with sufficient quality for grading lesions (drusen and retinal pigmentary abnormalities). Each image was graded twice using a modification of the severity scale of Age-Related Eye Disease Study (AREDS) by 2 retina specialists; a third specialist was consulted when the results of grading did not match between initial 2 reviewers.

Results: : The mean age and axial length of the study population were 62.7 years and 23.71mm (R: 23.72 mm, L: 23.69 mm), respectively. The study subjects included 64.2% female. Eighty-seven participants with other macular disease (such as epiretinal membrane) were excluded from the analysis. Early age-related macular degeneration (AMD) and late AMD were present in 21.3% and 0.22%, respectively. Number of participants with soft drusen (63 μm or larger) and retinal pigmentary abnormalities at least one eye were 1324 (41.5%) and 209 (6.6%), respectively; 38.2% and 15.8% of them had in both eyes, respectively. There was a significant association between size and bilaterality of drusen (P = 1.35 x 10^-7). Prevalence of soft drusen with high myopic patients (axial length greater than 26.0 mm or spherical equivalent ≤ -6.0 D) were significantly lower than those without high myopia (16.3%, P = 3.18 x 10^-8).

Conclusions: : These data describe AMD prevalence and characteristics in the Japanese and show higher prevalence of early AMD than that reported previously.

Keywords: age-related macular degeneration • drusen • clinical (human) or epidemiologic studies: prevalence/incidence