Changes of refraction, visual function and ocular biometrics of schoolchildren: Follow-up data of the WEPrOM Study in Wenzhou, China

Abstract

Purpose : The WEPrOM (Wenzhou Essilor Progression & Onset of Myopia) Study is a prospective school-based cohort study in both urban and rural areas in Wenzhou, China. A cohort of schoolchildren aged 7 to 9 years were recruited, with annual follow-up visits over a 4-year period. We aim to assess the changes in refraction, visual function and ocular biometrics of schoolchildren in rural and urban schools over a 2-year period.

Methods : We analyzed data from schoolchildren who attended the baseline, 1-year follow-up, and 2-year follow-up visits of WEPrOM study. Ocular examinations, including refraction and ocular biometry (Lenstar) were done. Visual function tests, including heterphoria, AC/A ratio, positive/negative relative accommodation (PRA/NRA), vergence, accommodative response were performed.

Results : A total of 1103 students were recruited at baseline, and 806 (248 and 558 from rural and urban schools, respectively) completed annual examination for the first 3 visits. At baseline, there were no significant differences of mean spherical equivalent (SE) between rural and urban students. At 2-year follow-up, the mean SE (± SD) of rural and urban students were 0.38 ± 0.97 D and 0.43±1.10 D, respectively. The mean annual change in SE was -0.22 ± 0.40 D/year in rural students and -0.26±0.48 D/year in urban students. The mean annual change in axial length (AL) was 0.28 ± 0.14 mm/year and -0.34 ± 0.18 mm/year in rural and urban students, respectively. There was significant difference of the annual change of AL between rural and urban students (P < 0.001). The mean annual change in lens thickness was -0.04 ± 0.05 mm in rural students and -0.05±0.05 mm in urban students. There was significant difference of the annual change of AL between rural and urban students (P = 0.02). There were no significant differences of visual functional parameters between rural and urban students (P < 0.05).

Conclusions : Myopic shift and longer AL were observed in both rural and urban students. The urban students seem to have faster elongation of axial length and faster thinning of lens thickness compared to rural students. A longer follow-up period is needed to investigate the differences between children from rural and urban schools.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.