Abstract
Purpose :
Evidence shows an association between exposure to evening blue light and pathologies. We found that evening blue light increased ocular growth; the effect was enhanced with higher intensity (2019 E-Abstract #3154). Here we asked if the effects of (1) exposure to blue light in the morning differed from evening; (2) exposure to blue evening light altered lens-induced myopia (LIM) and (3) exposure to high intensity white light affected LIM in a time-of-day-dependent manner.
Methods :
Birds were in a 12L/12D white light from hatch to 10d. Controls remained in white light for the 12 h “day”. Morning blue: Birds were exposed to 4h blue light from 7:30-11:30 for 9d: (200 lux=“mid”, n=9; 588 lux=“bright”, n=11. Controls, n=23). Evening blue & LIM: -10 D lenses were attached to one eye, and chicks were exposed to 4 h evening (15:30-19:30) “bright” (n=13) or “mid” (n=10) blue for 9d. Controls: n=11. Bright white & LIM: Birds wearing -10D lenses were exposed to 3h bright (30K lux) white light for 7d in morning (n=7) or evening (n=7). Controls: n=9. Ocular dimensions were measured at the start and end of the experiment using high frequency ultrasonography. Refractive errors were measured with a Hartinger’s refractometer.
Results :
Morning blue: Blue light in the morning resulted in significant growth stimulation (blue vs white: 856 vs 766 µm/9d; p<0.002; data for both intensities combined) similar to stimulation by evening blue (839 µm/9d). Evening blue & LIM: Bright blue light in the evening inhibited the development of LIM while “mid” blue enhanced it (X-C: -3.2 D and -9.4 D vs -6.4 D respectively; ANOVA p=0.002; bright vs mid p=0.001). The effect was axial (X-C: 202 µm and 603 µm vs 416 µm/9d; ANOVA p=0.0002; bright vs mid p=0.001). Bright white & LIM: Evening bright light inhibited ocular growth relative to that of morning bright light and to “not bright” controls (X-C: 233 µm vs 438 and 417 µm/7d; ANOVA p=0.02; p=0.03, p=0.059 respectively).
Conclusions :
Bright white or bright blue light in the evening inhibited the development of LIM, but mid-range blue enhanced it. The growth-enhancing effect of mid-range blue on the lens-wearing eyes parallels that of both intensities on normal eyes. The growth-inhibitory effect of bright blue light on lens compensation is consistent with that reported for lens-wearing chicks reared in blue light (Yu & Wildsoet, 2019 ARVO E-Abstract #4812)
This is a 2020 ARVO Annual Meeting abstract.