Lingham, GarethMackey, DavidZhu, KunLucas, RobynBlack, Lucinda JOddy, Wendy HHolt, PartickWalsh, John PSanfilippo, Paul GChan She Ping-Delfos, WendyYazar, Seyhan2024-02-221755-375Xhttp://hdl.handle.net/1885/313833Purpose To investigate the relationship between time spent outdoors, at particular ages in childhood and adolescence, and myopia status in young adulthood using serum 25-hydroxyvitamin D [25(OH)D] concentration as a biomarker of time spent outdoors. Methods Participants of the Raine Study Generation 2 cohort had 25(OH)D concentrations measured at the 6-, 14-, 17- and 20-year follow-ups. Participants underwent cycloplegic autorefraction at age 20 years, and myopia was defined as a mean spherical equivalent −0.50 dioptres or more myopic. Logistic regression was used to analyse the association between risk of myopia at age 20 years and age-specific 25(OH)D concentrations. Linear mixed-effects models were used to analyse trajectory of 25(OH)D concentrations from 6 to 20 years. Results After adjusting for sex, race, parental myopia, body mass index and studying status, myopia at 20 years was associated with lower 25(OH)D concentration at 20 years (per 10 nmol/L decrease, odds ratio (aOR)=1.10, 95% CI: 1.02, 1.18) and a low vitamin D status [25(OH)D < 50 nmol/L] at 17 years (aOR = 1.71, 95% CI: 1.06, 2.76) and 20 years (aOR = 1.71, 95% CI: 1.14, 2.56), compared to those without low vitamin D status. There were no associations between 25(OH)D at younger ages and myopia. Individuals who were myopic at 20 years had a 25(OH)D concentration trajectory that declined, relative to non-myopic peers, with increasing age. Differences in 25(OH)D trajectory between individuals with and without myopia were greater among non-Caucasians compared to Caucasians. Conclusions Myopia in young adulthood was most strongly associated with recent 25(OH)D concentrations, a marker of time spent outdoors.The Raine Study is supported by the University of Western Australia, Curtin University, the Raine Medical Research Foundation, Telethon Kids Institute, Edith Cowan University, Women and Infants Research Foundation, Murdoch University and The University of Notre Dame Australia. The 5-,14-, 17- and 20-year follow-ups of the Raine Studywere all supported by the National Health and Medical Research Council (specifically, grants 963209, 211912, 003209, 353514, 403981, 1022134 and 1021105). Analysis of the 17-year 25(OH)D samples was funded by the Ada Bartholomew Medical Research Trust. The 20-year follow-up of the Raine Study also received funding from Ophthalmic Research Institute of Australia (ORIA), Lions Eye Institute, the Australian Foundation for the Prevention of Blindness, and Alcon Research Institute. GL is supported by an Australian Government Research Training Stipend, RML is supported by a NHMRC Senior Research Fellowship, SY by a NHMRC CJ Martin Biomedical Fellowship, LJB by an MS Research Australia Postdoctoral Fellowship and a Curtin University Research Fellowship, and DAM by a NHMRC Practitioner Fellowshipapplication/pdfen-AU© 2021 Acta Ophthalmologica Scandinavica Foundation.vitamin Dmyopiathe Raine Studytime outdoors202110.1111/aos.147092022-10-09