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Tiffany Y Yanase, Mark A Henriksen, Christopher Patrick Taylor, Frances J Rucker; Blue light reduces eye growth at high temporal frequencies but only at high contrast levels. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5524.
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© ARVO (1962-2015); The Authors (2016-present)
Prior experiments in chicks have shown that blue light protected against temporal frequency dependent axial growth. This study varied both temporal frequency and temporal contrast to better represent how dynamic, real-world visual stimuli would stimulate the retina. The purpose of this study was to investigate the stability of blue light’s protective effects on emmetropization when changing both temporal contrast and frequency.
12-day-old White leghorn chicks were exposed to LED light modulated at either low (0.2 Hz) or high (10 Hz) white (with blue) or yellow light (without blue), in one of four contrast conditions: low (16% contrast), medium (32% contrast), medium-high (60% contrast) and high (80% contrast). There were 8-15 chicks in each condition. All chicks were exposed to the experimental lighting conditions for 8 hours on three consecutive days (mean illumination of 680 lux) and were housed in a dark chamber overnight. Refractive measurements were made before and after exposure to experimental conditions with a Hartinger Refractometer and axial dimensions were obtained with a LENSTAR LS900 optical biometer.
Contrast had an effect on reducing eye growth, but only with blue light. With blue, modulated at 10 Hz, a reduction in eye growth was seen in the 80% contrast condition, but not in any other contrast or frequency condition (Tukey’s HSD p<0.005). Contrast had no effect on eye length without blue light (p= 0.12). Contrast changes without blue light did not affect refraction (p= 0.39), anterior chamber depth (p= 0.26), or choroidal thickness (p= 0.82).Blue light protected the eyes against myopia; eyes became more myopic at low temporal frequencies without blue light (mean change at 0.2 Hz: -1.44D) than with blue light (mean change at 0.2 Hz: -0.1 D; p=0.001). This was partly due to less choroidal thinning at low temporal frequencies with blue light (p<0.001), but not without blue light. There was no difference in refractive error between with and without blue light conditions at high temporal frequencies (p=0.89).
Blue light’s protective effect against temporal frequency induced myopia requires a temporal contrast of 60% or greater.
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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