Temporal variations in myopia progression in Singaporean children within an academic year

Excessive nearwork is believed to be associated with myopia development and progression. To investigate this further, we studied refractive error changes and their correlation with nearwork in a cohort of grade school children in Singapore.

Cycloplegic autorefraction was performed 5 times over 10 months on 168 children aged 7, 9, and 12 years who were further divided into myopic and nonmyopic subgroups based in their initial refractive errors. Information about nearwork was obtained through diaries filled out over 24 h at the commencement of the study.

Myopia progression was high (overall mean: -0.87 D per year) and largely linear throughout the year, but significantly higher rates were seen after the final school examinations in 7-year-old myopes and nonmyopes. Overall, myopic groups exhibited higher progression rates than nonmyopic groups, although 33.6% of subjects from the latter groups had become myopic by the end of the study. Nearwork scores derived from the diaries were generally not well correlated with overall myopia progression.

The tendency for myopia progression rates to increase after the final school examinations in 7-year-olds is interpreted as a delayed effect of the intense nearwork associated with preparing for them. The timing of nearwork-diary data collection at the beginning of the study could be responsible for the poor correlation between these data and overall myopia progression rates.