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Kara Gerger, Jane Gwiazda; Larger refractive group differences in visual activities are found in children than in young adults. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5696.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate refractive group differences in time spent on indoor and outdoor activities at the current age and at 10 years.
46 young adults (mean age = 24.15±2.21 years) completed a visual activities questionnaire asking them to recall their daily activities at 10 years of age and currently, separately for winter and summer. Subjects indicated the average time spent daily on a variety of indoor and outdoor activities requiring either distance (e.g., exercise/sports) or near vision (e.g., reading). Hours of weekly activity were calculated as follows: (weekday hours x 5) + (weekend day hours x 2). Myopia was defined as spherical equivalent refraction (SER) ≤ -0.50 D and non-myopia as SER between -0.49 D and +2.00 D. Refractive group differences in activity time were compared by t-tests.
28 myopes (mean SER = -2.47±1.30 D) and 18 non-myopes (mean SER = +0.39±0.38 D) were tested. Overall, significant refractive group differences were found at 10 years, especially in outdoor physical activity. At 10 years, myopes spent significantly fewer hours per week in outdoor physical activity than non-myopes, both in the winter (8.68±5.26 vs. 13.36±6.49 hrs/wk; p=0.015) and summer (19.11±10.05 vs. 27.89±8.66 hrs/wk; p= 0.003). At 10 years myopes also reported significantly more hours of indoor near activity than non-myopes in the summer (19.07±8.07 vs. 13.67±7.51 hrs/wk; p=0.026), but not in the winter (20.39±6.80 vs. 18.14±6.69 hrs/wk; p=0.276). The correlation between outdoor physical activity and indoor near activity in the summer was small and not significant (R=0.165), suggesting no substitution effect. For the same activities at the current age no significant refractive group differences were found.
Myopes spent less time than non-myopes in outdoor physical activity and more time on indoor near activity at 10 years, especially in the summer, but not at their current age. In addition, the majority (71%) of the myopes were first corrected after 10 years of age. These results, taken together, suggest that more outdoor physical activity and less indoor near activity might reduce the risk for development of myopia in children.
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