Children with myopia who have undercorrected refractive error may demonstrate shorter reading distances, according to a study published in Ophthalmology Therapy. This finding suggests that using undercorrection for myopia control may not be an optimal strategy, and the shortened reading distance could potentially contribute to an increased progression.
“Wearing spectacles is effective in correcting myopia, restoring [visual acuity], and preventing visual loss in children, yet inadequate corrections remain very common,” according to the study authors. “Undercorrection itself has become one of the causes for visual impairment among schoolchildren in developing countries.”
Researchers included 2363 pediatric patients (52.6% boys; mean age, 7.64 years) in the population-based, cross-sectional study and compared reading distances between children with undercorrected myopia, fully corrected myopia, and without myopia. The participants underwent cycloplegic autorefraction, subjective refraction, and best- corrected visual acuity assessment. As the children read a passage from a popular comic surrounded by conditions that simulated a classroom environment, the research team measured reading distance at 6, 7, 8, and 9 minutes after initiating the activity.
The habitual reading distances of children with myopia who were undercorrected (23.37 cm) were significantly shorter compared with reading distances in children without myopia (24.20 cm; P=.002) and children with myopia who wore their full spectacle correction (24.81 cm; P < .001). A shorter reading distance was associated with myopia (odds ratio [OR], 1.67; 95% CI, 1.11-2.51; P = .013) after adjusting for age, sex, height, near work time, outdoor time, and parental myopia, according to the report.
No correlation was established between reading distance and myopia after excluding participants who were undercorrected from the analysis (OR 0.97; 95% CI, 0.55-1.73; P = .92). A shorter reading distance correlated with poorer vision under habitual correction (β=- 0.003; P <.001).
“Compared to non-myopic and fully corrected myopic children, undercorrected myopic children exhibited the shortest reading distance. Furthermore, our results showed that a greater amount of near work time is consistently associated with myopia,” according to the researchers. “Our results indicate that the therapeutic strategy of myopia undercorrection among children may not only be unwarranted but may also be potentially harmful.”
Study limitations include failure to test in environments outside of a classroom setting, a short study duration, and homogeneity that may limit the globalization of these findings.
Tang SM, Zhang XJ, Wang YM, et al. Effect of myopic undercorrection on habitual reading distance in schoolchildren: the Hong Kong Children Eye Study. Ophthalmol Ther. Published online December 27, 2022. doi:10.1007/s40123-022-00628-2