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Jon V. B. Gjelle, Lene Aarvelta Hagen, Solveig Arnegard, Stuart J. Gilson, Rigmor C Baraas; Prevalence of refractive errors and self-reported near-work, indoor and outdoor activities in Norwegian adolescents. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3985. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the prevalence of refractive errors and asses the relationship with self-reported activity during out-of-school indoor and outdoor time among students in a Norwegian high school.
A cross-sectional study was carried out in a high school in a municipality in Southeast Norway. 204 students (30%) of mean age 17.9 [range 16–25] yrs completed a digital questionnaire and vision screening. Measurements of objective refractions were obtained with Huwitz HRK-8000A Auto-REF Keratometer after administering Cyclopentolate 1%. Ocular axial length (AL) and corneal radius (CR) were measured with Zeiss IOLMaster 500.
Mean habitual visual acuity was 0.11 [range -0.20–1.32] logMAR. The prevalence of myopia (SER≤-0.50D), emmetropia (>-0.50D to <+1.00D), mild hyperopia (≥+1.00D to <+2.00D), moderate to high hyperopia (≥+2.00D) and astigmatism (cylinder ≥0.75D) were 18%, 59%, 17%, 6% and 19%, respectively. Mean dominant ocular axial length was 23.4mm [range 21.1–27.0] and corneal radius was 7.8mm [range 7.2–8.4], resulting in AL/CR of 3.0 [range 2.7–3.5]. There was a slight correlation between both AL and CR with average time near work (r=0.153, p=0.029 and r=0.165, p=0.019, respectively). Mean outdoor activity was 3.8 [range 0.0–8.7] hours/day, indoor activity 2.5 [range 0.0–6.0] hours/day and near-work hours/day outside the school day was 5.8 [range 0.7–11.8]. Emmetropes spent more time outdoors than myopes and hypermetropes [50 minutes/day and 20 minutes/day; F(22.6, 689.6)=11.3, p=0.04]. There was no difference between groups on time spent on indoor activities or near-work hours.
Myopia is less frequent whereas hypermetropia is more frequent in Norwegians than what is reported for the same age group in Asia. Norwegian adolescents, however, appears to spend no more time outdoors than for example Singapore adolescents [Dirani, et al. (2009) B J Ophtalmol 93:997–1000]. It is not known what might protect Norwegians from developing myopia at the same rate as their Asian peers.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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