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Exp Eye Res. 2013 Sep;114:48-57. doi: 10.1016/j.exer.2013.05.004. Epub 2013 May 13.

Light levels, refractive development, and myopia--a speculative review.

Author information

1
Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, USA. tnorton@uab.edu

Abstract

Recent epidemiological evidence in children indicates that time spent outdoors is protective against myopia. Studies in animal models (chick, macaque, tree shrew) have found that light levels (similar to being in the shade outdoors) that are mildly elevated compared to indoor levels, slow form-deprivation myopia and (in chick and tree shrew) lens-induced myopia. Normal chicks raised in low light levels (50 lux) with a circadian light on/off cycle often develop spontaneous myopia. We propose a model in which the ambient illuminance levels produce a continuum of effects on normal refractive development and the response to myopiagenic stimuli such that low light levels favor myopia development and elevated levels are protective. Among possible mechanisms, elevation of retinal dopamine activity seems the most likely. Inputs from intrinsically-photosensitive retinal ganglion cells (ipRGCs) at elevated light levels may be involved, providing additional activation of retinal dopaminergic pathways.

KEYWORDS:

animal models; dopamine; form-deprivation myopia; illuminance; lens-induced myopia; myopia; refractive development

PMID:
23680160
PMCID:
PMC3742693
DOI:
10.1016/j.exer.2013.05.004
[Indexed for MEDLINE]
Free PMC Article
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