title: Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes.
abstract: OBJECTIVE
  Time spent outdoors is protective against myopia. The outdoors allows exposure to short-wavelength (blue light) rich sunlight, while indoor illuminants can be deficient at short-wavelengths. In the current experiment, we investigate the role of blue light, and temporal sensitivity, in the emmetropization response.
  
  
  METHODS
  Five-day-old chicks were exposed to sinusoidal luminance modulation of white light (with blue; N = 82) or yellow light (without blue; N = 83) at 80% contrast, at one of six temporal frequencies: 0, 0.2, 1, 2, 5, 10 Hz daily for 3 days. Mean illumination was 680 lux. Changes in ocular components and corneal curvature were measured.
  
  
  RESULTS
  Refraction, eye length, and choroidal changes were dependent on the presence of blue light (P < 0.03, all) and on temporal frequency (P < 0.03, all). In the presence of blue light, refraction did not change across frequencies (mean change -0.24 [diopters] D), while in the absence of blue light, we observed a hyperopic shift (>1 D) at high frequencies, and a myopic shift (>-0.6 D) at low frequencies. With blue light there was little difference in eye growth across frequencies (77 μm), while in the absence of blue light, eyes grew more at low temporal frequencies and less at high temporal frequencies (10 vs. 0.2 Hz: 145 μm; P < 0.003). Overall, neonatal astigmatism was reduced with blue light.
  
  
  CONCLUSIONS
  Illuminants rich in blue light can protect against myopic eye growth when the eye is exposed to slow changes in luminance contrast as might occur with near work.
authors.forename: Frances
authors.initials: F
authors.lastname: Rucker
authors.forename: Stephanie
authors.initials: S
authors.lastname: Britton
authors.forename: Molly
authors.initials: M
authors.lastname: Spatcher
authors.forename: Stephan
authors.initials: S
authors.lastname: Hanowsky
mesh_terms: D000818:Animals; D002645:Chickens; D004195:Disease Models, Animal; D005260:Female; D008027:Light; D008297:Male; D010775:Photic Stimulation; D012029:Refraction, Ocular / Q000528:radiation effects*; D012030:Refractive Errors / Q000503:physiopathology / Q000532:radiotherapy*