Progression of Refractive Errors in Low-Income Urban School-Age Children of Sao Paulo, Brazil

Abstract

Purpose: : Previous population-based Refractive Error Study in Children (RESC) surveys have shown that refractive error (RE) is mainly a problem among children attending schools. It is also known that myopia is related to increasing age as well as with the educational/socio economic status of the family, probably related to the emphasis on reading and other near vision tasks associated with school performance. Our objective is to evaluate RE progression and its related risk factors in a cohort of low-middle income school children previously included in a population-based study in Brazil.

Methods: : The baseline study population consisted of children from 5^th to 8^th grades (11-14 years of age) from 9 randomly chosen public schools included in the RESC study performed in Brazil in 2004-2005, with refraction performed only in those with visual impairment (uncorrected visual acuity ≤ 20/40 in either eye). Eligible participants for the follow-up study were those identified in the baseline study as visually impaired (VI) as well as those without VI attending the 5^th grade. Three years later, recruitment consisted of invitation for a free ophthalmic exam in the school facilities. Cycloplegic auto-refraction, cycloplegic subjective refraction and fundus examination were performed in those refracted at baseline and in those with VI at follow-up. RE risk factors were investigated by administering questionnaires on family demographics, parental glasses usage and near work/outdoor activities.

Results: : In the baseline study 2825 school children were enumerated and 2441 (86.4%) were examined. A cohort of 867 children (218 previously identified as VI and 649 former 5^th graders without VI) was eligible for the follow-up with 522 (60.2%) examined (136 with VI and 384 former 5^th graders without VI). A refractive error change of 0.50D or 1.5D was found, respectively in 74.3% and 22.8% of the 136 children with VI. In the remaining group, 26 children with VI were detected at follow-up. In multiple regression analysis, RE ≥0.50D in at least one eye was almost significantly (P=0.07) associated with younger age. No association was found between refractive error progression and near work/outdoor activities.

Conclusions: : Very mild refractive error progression was detected in a low-income urban Brazilian school children, confirming the previous finding of low prevalence of RE leading to visual impairment in this population.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment • refractive error development • visual acuity