Axial Length and Prevalence of Myopia among Schoolchildren in the Equatorial Region of Brazil

Abstract

The prevalence of myopia is increasing globally, and the outdoor light environment is considered as a possible factor that can retard myopia. The aim of this study was to evaluate the prevalence of myopia and the light environment in Aracati, equatorial Brazil. We surveyed 421 children (421 right eyes; mean age, 10.6 years) and performed ocular examinations that included non-cycloplegic refraction and axial length (AL). Multiple regression analyses were performed to identify factors affecting myopia such as time spent outdoors and in near work. We measured illuminance and violet light irradiance in Aracati. The mean spherical equivalent (SE) and AL were −0.44 ± 1.38 diopters (D) and 22.98 ± 0.87 mm, respectively. The prevalence of myopia (SE ≤ −0.75 D) and high myopia (SE ≤ −6.0 D/AL ≥ 26.0 mm) was 20.4 and 1.4/0.48%, respectively. Multiple regression analyses showed that myopia was not associated with lifestyle factors. The average illuminance in Aracati was about 100,000 lux from morning to evening. The current results reflect the ALs and the prevalence of myopia among Brazilian schoolchildren. There is a possibility that the light environment in addition to other confounding factors including racial differences affects the ALs and refractive errors.

Keywords

• myopia
• refractive error
• axial length
• school children
• light environment
• violet light