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Patrick Nelson, Jane Gwiazda; Effects of Outdoor Exercise on Axial Length and Choroidal Thickness in Myopic and Emmetropic Young Adults. Invest. Ophthalmol. Vis. Sci. 2012;53(14):152.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the effect of outdoor exercise on ocular biometric measurements in young adults with a wide range of refractions, to gain further insight into factors that may contribute to myopia development and progression.
22 young adults (mean age = 23.5 years; 12 myopes (mean Rx = -2.12 D), 10 emmetropes (mean Rx = +0.22 D)) participated in the study. After baseline measurements of refractive error (Grand-Seiko Autorefractor) and biometry (Haag-Streit Lenstar; axial length (AL), choroidal thickness, central corneal thickness, retinal thickness, anterior chamber depth, and lens thickness) were taken, subjects then engaged in 10 minutes of moderate outdoor running. The same biometric measurements were recorded 0, 5, and 10 minutes after exercise. Subjects then spent 10 minutes sitting outside as an outdoor exposure control condition, and the same measurements were recorded at 0, 5, and 10 minutes. Outdoor light levels were recorded during each session. Analyses of variance and t-tests were used for statistical analysis of the data.
Immediately after exercise, mean AL decreased by 6.0 ± 3 μm and then returned to baseline levels over the next 10 minutes. None of the changes in AL were statistically significant. Mean AL for myopes increased slightly after exercise by +3.3 μm, while that for emmetropes decreased by 20 μm(P = 0.12). There were no significant changes after exercise in any of the other components. However, changes in the choroid were opposite to those in AL for emmetropes and myopes. Overall, the outdoor exposure control condition showed a similar maximum mean decrease in AL (6.5 ± 2μm) to the exercise condition but with a difference time course (delayed 5 minutes). Mean light levels were 75000 lux ± 38000.
Contrary to results of a recent study that showed significant decreases in AL after indoor exercise, outdoor exercise for 10 minutes did not produce a significant change in axial length or other ocular components in young adults. The trends in refractive group differences were suggestive. Therefore, measurement of AL and choroidal thickness in additional myopes (especially progressing) and emmetropes is warranted.
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