Abstract
Purpose: :
To determine the prevalence and relating factors of refractive errors in the adult population in a rural southern island of Japan.
Methods: :
A population-based ophthalmological survey was conducted from March 2005 to August 2006 in Kumejima Island, Okinawa, Japan. Of all 4632 residents with age of 40 yrs or older, 3762 (response rate, 81.2%) underwent detailed ocular examination including autokeratorefractometry, subjective, refraction, best-corrected visual acuity, central corneal thickness measurement, intraocular pressure measurement, slit-lamp examination, fundus photography, and visual field testing. The prevalence of myopia (spherical equivalent [SE] <-0.5 diopters [D]), high myopia (<-5 D), hyperopia (>0.5 D), refractive astigmatism (cylinder >0.5 D) were determined, and the correlation of refractive errors with age, gender, axial length, and central corneal thickness were analyzed.
Results: :
SE averaged 0.02 ± 1.92 and 0.09 ± 1.90 D in right and left eyes, respectively, with significant bilateral difference (P<0.001, paired t-test). The crude prevalence of myopia, high myopia, hyperopia, and refractive astigmatism was 31.1%, 2.2%, 41.7%, and 49.8%, respectively. The prevalence of myopia decreased with age up to 60 to 69 years but increased slightly in patients 70 years and older; the prevalence of hyperopia showed the opposite trend. The prevalence of astigmatism was higher in the older age groups. In multiple regression analysis, SE was significantly positively correlated with age (partial correlation coefficient [PCC] =0.34, P<0.001) and negatively with axial length (PCC=-0.56, P<0.001).
Conclusions: :
The prevalence of myopia in a southern island of Japan was less than that in an urban city in Japanese Main Land (41.5%, Tajimi City), while was similar or a bit higher than that reported from other countries.
Keywords: refraction • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • clinical (human) or epidemiologic studies: prevalence/incidence