Visual Acuity, Visual Function and Myopia Among Rural Chinese Secondary School Children: The X-PRES Study

Abstract

 

Purpose:

 

Though uncorrected refractive error is the leading cause of low vision among children in Asia, the impact of myopia on visual function has not been well-described in this setting. We sought to evaluate visual acuity, visual function and prevalence of refractive error among rural Chinese secondary-school children.

 

Methods:

 

Uncorrected, presenting and best-corrected visual acuity, cycloplegic auto-refraction with ophthalmologist's refinement and self-reported visual function using a standard instrument (Fletcher et al. Arch Ophthalmol 1997;115:767-774) were assessed in a random, cluster sample of students drawn from all secondary schools in the town of Xichang in Southern China.

 

Results:

 

Among 1892 subjects (97.3% of consenting children, 84.7% of total sample), mean age was 14.7 +/- 0.8 years, 51.2% were female and 26% were wearing glasses. The proportion of children with uncorrected, presenting and best-corrected low vision (<= 6/12 in the better eye) was 41.2%, 19.3% and 0.5% respectively. Myopia < -0.5D, < -2.0D and < -6.0D in both eyes was present in 62.3%, 31.5% and 1.8% of subjects respectively. Among children with low vision when tested without correction, 98.7% was due to refractive error, while only half of these children had appropriate correction. Girls had significantly (P < 0.001) more low vision and myopia than boys. More myopic refractive error was strongly associated with worse self-reported visual function (Correlation = 0.46, P < 0.001, Table 1).

 

Conclusions:

 

Visual disability in this population was common, highly correctable, and frequently un-corrected. The impact of refractive error on self-reported visual function was significant. Strategies and studies to understand and remove barriers to spectacle wear are needed.Table 1: Association between spherical equivalent (average between two eyes) and visual function score (ranges from 0 (worst) to 100 (best))  

 

Keywords: myopia • clinical (human) or epidemiologic studies: health care delivery/economics/manpower • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials