Intensive outdoor activity for 1 week increased choroidal thickness

Abstract

Purpose : The increasing myopia prevalence globally is a relatively recent social health problem. Outdoor activity is an evidence-based environmental factor that protects against myopia progression. The purpose of the current study was to study the positive ocular effects of intensive outdoor activity for only 1 week.

Methods : Children aged 10 to 13 years participated in an intensive outdoor activity program, i.e., more than 2hours on the first day, 3 hours on the second day, and 6 hours daily on subsequent days for a total of 6 days during the 2021 summer vacation at the National Akagi Youth Friendship Center. Eye examinations included measurement of the refractive error using the HOYA iTrace Surgical Workstation (Tracey Technologies) and axial length and corneal thickness using swept-source optical coherence tomography (SS-OCT) biometry (IOLMaster700, Carl Zeiss Meditec AG), choroidal thickness using SS-OCT (Xephilio OCT-S1, Canon), tear fluid volume (Schirmer test and strip meniscometry test), and a questionnaire. These parameters were analyzed at the start and end of the program using the paired-t test. Data from the left eyes were analyzed.

Results : Seventeen children (mean±standard deviation age, 12.0±1.0 years; 47.1% female) were included. The baseline and final choroidal thicknesses were, respectively, 359.5±121.7 and 397.4±122.1 µm (p < 0.001). The respective central corneal thicknesses also differed significantly, i.e., 579.0±45.6 and 584±44.6 µm (p < 0.002). The refractive errors and axial lengths did not differ significantly, -1.69±1.48 diopters (D) vs -1.83±1.87 D (p = 0.201) and 24.15±0.97 mm vs 24.15±0.96 mm (p = 0.463). The tear fluid volume did not differ significantly between the start and end of the program.

Conclusions : Our results suggested that intensive outdoor activity even for 1 week increased the choroidal thickness in Japanese schoolchildren. Further studies are needed to assess the effects in more subjects and thelong term.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.