Seasonal variation of refractive error change among young schoolchildren in a population-based cohort study in Taipei

• Published in: British journal of ophthalmology Vol. 103; no. 3; pp. 343 - 348
• Main Authors: Tsai, Der-Chong, Huang, Nicole, Fang, Shao-You, Hsu, Chih-Chien, Lin, Pei-Yu, Chen, Shing-Yi, Liou, Yiing-Mei, Chiu, Allen Wen-Hsiang, Liu, Catherine Jui-Ling
• Format: Journal Article
• Language: English
• Published: BMA House, Tavistock Square, London, WC1H 9JR BMJ Publishing Group Ltd 01.03.2019; BMJ Publishing Group LTD
• Subjects: child health (paediatrics); Childrens health; Clinical science; Cohort analysis; Data analysis; Epidemiology; Eye examinations; Investigations; Light; Myopia; Ophthalmology; optics and refraction; Outdoor activities; Outdoors; Pediatrics; Population; Population-based studies; Questionnaires; Risk factors; Seasonal variations; China; Taiwan; child health (paediatrics); epidemiology; optics and refraction
• ISSN: 0007-1161; 1468-2079
• DOI: 10.1136/bjophthalmol-2017-311642

PurposeTo investigate the relationship between seasonal variation of daylight length and spherical equivalent (SE) progression among the schoolchildren participating in the Myopia Investigation Study in Taipei.MethodsWe used the first-year data from grade 2 schoolchildren who completed all the baseline and two follow-up examinations (n=6790). There were two 6-month intervals between visits over winter and summer, respectively. For each interval, we calculated average daily daylight length using data from Taiwan’s Central Weather Bureau and measured 6-month SE progression rate based on right eye cycloplegic autorefraction data. The midpoint month was defined as the month midway between two consecutive visits.ResultsBy the midpoint month, average daily daylight length was the shortest in December (671±7 min/day) and the longest (785±7 min/day) in June, and SE progression rate was the fastest (−0.23±0.48 D) in December and the slowest (−0.17±0.51 D) in June. Significant variation of SE progression rate with season can be observed only among the schoolchildren (n=1905) whose midpoint months for the winter and summer intervals were December and June (winter rate, −0.25±0.47 D; summer rate, −0.17±0.49 D; p<0.001). Of those, the summer progression rate was approximately 80%, 65% and 61.5% of that measured in winter for myopic (p=0.252), emmetropic (p=0.012) and hyperopic (p=0.012) schoolchildren, respectively.ConclusionOur data demonstrate a seasonal variation of minus shift in refractive error among Taipei schoolchildren who had significant daytime fluctuation during the 1-year follow-up. Of those, non-myopic children had significant and more pronounced variation of SE progression than myopic children.