The Effect of Ambient Illuminance on the Development of Deprivation Myopia in Chicks
Regan Ashby 1*,
Arne Ohlendorf 2,
and
Frank Schaeffel 3
1 Section of Neurobiology of the Eye, Institute for Ophthalmic Research, University of Tuebingen, Institute for Ophthalmic Research, University of Tuebingen, Section of Neurobiology, Calwerstrasse 7/1, 72076, Tuebingen, Germany, Tuebingen, 72076, Germany
2 Section of Neurobiology of the Eye, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
3 Section of Neurobiology of the Eye, University Eye Hospital Tuebingen, Tuebingen, Germany
* To whom correspondence should be addressed. E-mail: regan.ashby{at}klinikum.uni-tuebingen.de.
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Abstract |
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Purpose: Recent epidemiological studies have shown that children who spend a higher proportion of time outdoors are less likely to develop myopia. We have investigated whether light levels may be a relevant factor in the development of myopia.
Methods: Paradigm 1: chicks were form-deprived for 5 days, with the translucent diffusers removed daily for 15 min under one of three lighting conditions (1) normal laboratory lighting (500 lux), (2) intense laboratory lighting (15,000 lux), or (3) daylight (30,000 lux). Paradigm 2: continuously form-deprived chicks were raised for four days under one of three lighting conditions: (1) low laboratory lighting (50lux), (2) normal laboratory lighting (500 lux), or (3) intense laboratory lights (15,000 lux). Axial length and refraction were measured at the commencement and cessation of treatment, with corneal curvature measured additionally in paradigm 2.
Results: Chicks exposed daily to either sunlight or intense laboratory lights for 15 min had significantly shorter eyes (8.81±0.05mm, p<0.01; 8.88±0.04mm; p<0.01) and less myopic refractions (-1.1±0.45D, p<0.01; -3.4±0.6D; p<0.01) than chicks which had their diffusers removed under normal laboratory light levels (8.98±0.03mm, -5.3±0.5D). Continuously form-deprived chicks reared under high light levels had shorter eyes (8.54±0.02mm; p<0.001) and less myopic refractions (+0.04±0.7D; p<0.001) compared to those chicks reared under normal light levels (8.64±0.06mm, -5.3±0.9D). Low lighting (50 lux) did not further increase deprivation myopia.
Conclusions: Exposing chicks to high light levels, either sunlight or intense laboratory lights, retards the development of experimental myopia.
Key Words:
myopia, form deprivation, eye growth, outdoor activity
