This study focused on a cohort that has not been studied and who currently have limited access to eye care services. The findings, while improving the understanding of the distribution of refractive errors, also enabled identification of children requiring intervention and provided a guide for future resource allocation.
The aim of conducting the study was to determine the prevalence and distribution of refractive error and its association with gender, age, and school grade level.
Using a multistage random cluster sampling, 1586 children, 632 males (40%) and 954 females (60%), were selected. Their ages ranged between 13 and 18 years with a mean of 15.81 ± 1.56 years. The visual functions evaluated included visual acuity using the logarithm of minimum angle of resolution chart and refractive error measured using the autorefractor and then refined subjectively. Axis astigmatism was presented in the vector method where positive values of J0 indicated with-the-rule astigmatism, negative values indicated against-the-rule astigmatism, whereas J45 represented oblique astigmatism.
Overall, patients were myopic with a mean spherical power for right eye of −0.02 ± 0.47; mean astigmatic cylinder power was −0.09 ± 0.27 with mainly with-the-rule astigmatism (J0 = 0.01 ± 0.11). The prevalence estimates were as follows: myopia (at least −0.50) 7% (95% confidence interval [CI], 6 to 9%), hyperopia (at least 0.5) 5% (95% CI, 4 to 6%), astigmatism (at least −0.75 cylinder) 3% (95% CI, 2 to 4%), and anisometropia 3% (95% CI, 2 to 4%). There was no significant association between refractive error and any of the categories (gender, age, and grade levels).
The prevalence of refractive error in the sample of high school children was relatively low. Myopia was the most prevalent, and findings on its association with age suggest that the prevalence of myopia may be stabilizing at late teenage years.
Discipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, South Africa (both authors) *email@example.com
Submitted: June 13, 2016
Accepted: August 29, 2017
Funding/Support: None of the authors have reported funding/support.
Conflict of Interest Disclosure: None of the authors have reported a conflict of interest.
Author Contributions and Acknowledgments: Conceptualization: SOW; Investigation: SOW; Methodology: SOW; Supervision: RH; Writing — Original Draft: SOW; Writing — Review & Editing: SOW, RH.
The authors thank Prof. David Goss (Indiana University) and Dr. Percy Mashige (University of KwaZulu-Natal, South Africa) for reviewing drafts of this manuscript. S.O.W. remain indebted to Profs. Dominic Maino (Illinois College of Optometry) and Marc Taub (Southern College of Optometry, Tennessee) for their continued kindness and guidance.