Preventing Myopia Progression by Novel Blue-SAD light therapy and the Potential Role of Nitric Oxide
Background: An alarming increase in prevalence has made myopia (near-sightedness) a worldwide health concern. Presently, there is no effective and widely accepted treatments for myopia. However, recent research shows outdoor light may prevent myopia, even with long periods of near-work. Outdoor light contains a large portion of short-wavelength (‘blue’) light. Therefore, I tested whether only blue-light prevents form-deprivation myopia in chicks. I also tested whether nitric oxide (NO), a known modulator of eye growth, was implicated in the underlying mechanisms. Understanding retinal mechanisms involved can assist in developing more specific therapies.
Hypothesis: Blue light inhibits myopia in chicks better than red or white light. NO may be involved in the signaling cascade that prevents myopia.
Methods: Goggled chicks were treated with 0h (control), 0.5h, 1.5h, or 3.0h by 10,000-lux SAD-lights, either unfiltered (white) or filtered to pass only short or long wavelengths. For NO experiments, chicks were injected with 300uM L-NMMA, a NO synthase inhibitor, prior to light treatment. Refractive error, axial length, equatorial diameter, and wet weight were measured and one-way ANOVA (p<0.05) was applied.
Results: Blue light significantly reduced myopia development, while white light only reduced myopia at 3h. Red light appeared to induce myopia. Injection of L-NMMA abolished the anti-myopic effect.
Conclusions: Sunlight may inhibit myopia because of its high content of blue-light. Short-wavelength light inhibits FDM in chicks via a signalling cascade in which NO mediates an obligatory step. For preventing myopia, understanding the blue-light mechanism may help understand how myopia progresses.
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