April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Outdoor Exposure Does Not Inhibit Experimental Myopia
Author Affiliations & Notes
  • Richard A Stone
    Ophthalmology, Univ of Pennsylvania School of Medicine, Philadelphia, PA
  • Yuval Cohen
    Ophthalmology, Univ of Pennsylvania School of Medicine, Philadelphia, PA
  • Alice M McGlinn
    Ophthalmology, Univ of Pennsylvania School of Medicine, Philadelphia, PA
  • Sherrill Davison
    Laboratory of Avian Medicine and Pathology, New Bolton Center, Kennett Square, PA
  • Susan Casavant
    Laboratory of Avian Medicine and Pathology, New Bolton Center, Kennett Square, PA
  • Jiayan Huang
    Ophthalmology, Univ of Pennsylvania School of Medicine, Philadelphia, PA
  • Tejvir S Khurana
    Physiology, Univ of Pennsylvania School of Medicine, Philadelph1a, PA
  • Machelle T Pardue
    Ophthalmology, Emory University School of Medicine, Atlanta, GA
    Rehab R&D Center of Excellence, Atlanta VA Medical Center, Atlanta, GA
  • P Michael Iuvone
    Ophthalmology, Emory University School of Medicine, Atlanta, GA
  • Footnotes
    Commercial Relationships Richard Stone, None; Yuval Cohen, None; Alice McGlinn, None; Sherrill Davison, None; Susan Casavant, None; Jiayan Huang, None; Tejvir Khurana, None; Machelle Pardue, None; P Iuvone, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 3039. doi:
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      Richard A Stone, Yuval Cohen, Alice M McGlinn, Sherrill Davison, Susan Casavant, Jiayan Huang, Tejvir S Khurana, Machelle T Pardue, P Michael Iuvone; Outdoor Exposure Does Not Inhibit Experimental Myopia. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3039.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: Rearing chicks and mammals under high-intensity laboratory lighting inhibits form-deprivation myopia, and it has been proposed that increasing outdoor exposure of children might favorably influence clinical myopia. We assessed the effects of "real-world" outdoor exposures on goggle-induced myopia in chicks.

Methods: Two cohorts of white Leghorn chicks, after placement of a uniocular translucent goggle at 5 or 9 days of age, were reared outdoors in a rural setting during daylight hours to the extent permitted by weather; they were not exposed to electric lighting. Two control cohorts were reared under incandescent lighting (500 lux) without outdoor lighting exposure, with light cycle durations matched to sunrise-sunset times of the outdoor chicks. Retinal dopamine/DOPAC (HPLC with electrochemical detection) and ocular refractions/dimensions (refractometry, ultrasound) were measured after 10 or 11 days. Analysis used paired t-test or one-way ANOVA.

Results: Non-goggled eyes had some 2.7 diopters (D) of hyperopia in all cohorts. The cohorts of goggled eyes averaged 12-23 D of myopia relative to control eyes, with no evidence that outdoor rearing lessened the myopic response. In fact, the myopic response was exaggerated in goggled eyes of the older outdoor vs. indoor cohort (-23 vs. -13 D; P<0.001). Similarly, the vitreous chambers and axial lengths were elongated in goggled eyes relative to controls, also with no evidence that outdoor rearing attenuated the myopic response (P>0.05, all between-cohort comparisons). In the younger cohort, retinal dopamine or DOPAC (pg/mg protein) in non-goggled eyes and the reductions in contralateral goggled eyes (dopamine ~15%; DOPAC ~48%) were similar between indoor and outdoor reared chicks (P>0.4, all between-cohort comparisons).

Conclusions: Contrary to current hypotheses, outdoor exposure does not reproduce the anti-myopia effects of increasing artificial lighting intensity in the lab, at least in chicks. The outdoor environment has much variability in richness of scene and chromaticity, along with major shifts in illumination from movement/density of clouds, individual movement into and out of shady areas, and direction of gaze. All these features were inherent to our study. While some element of outdoor and/or lighting exposure may favorably affect refractive development, our results point to a level of complexity that is not being adequately considered in laboratory or clinical investigations.

Keywords: 605 myopia • 677 refractive error development • 502 dopamine  
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