Clinicians may want to take the season into consideration when evaluating school-aged children for refractive shifts, according to research. A recent study conducted among Taipei schoolchildren found a seasonal variation in refractive error among the Taiwanese children who demonstrated significant daytime fluctuation.

Researchers used data from second grade students who had completed baseline and six follow-up examinations, two during the winter and two during the summer. During follow-up, they calculated the average daily daylight length and measured spherical equivalent (SE) progression rates based on right eye cycloplegic autorefraction data. They defined the midpoint month as the month midway between consecutive visits.

By the midpoint month, average daylight length was the shortest in December and the longest in June—and SE progression rates were the fastest in December and the slowest in June. Of the schoolchildren whose midpoint months were December and June, the study found “the summer progression rate was approximately 80%, 65% and 61.5% of that measured in winter for myopic, emmetropic and hyperopic schoolchildren, respectively.”

The researchers conclude that “non-myopic children had significant and more pronounced variation of SE progression than myopic children.”

Tsai D, Huang N, Fang S, et al. Seasonal variation of refractive error change among young schoolchildren in a population-based cohort study in Taipei. Br J Ophthalmol. May 23, 2018. [Epub ahead of print].