Wearing blue-green blocking lenses in the evening inhibits ocular growth rate in chicks

Abstract

Purpose : Blue light in the evening phase-delays the dim light melatonin onset rhythm, and is associated with various pathologies. Blue-blocking lenses prevented the phase-delay in humans (2019 ARVO E-Abstract #5269). In chicks, while rearing in blue light inhibited ocular growth, brief daily exposures to blue light in the morning or evening stimulated ocular growth (2020 ARVO E-Abstract 3407), which, if translatable, might predispose children to myopia. We tested the effects of blue-green blocking lenses (Essilor: block 70% in the circadian band of 460-510nm; Tv(D65) = 77%) on ocular growth rates in chicks.

Methods : Experiments began at age 12-14 days. The light cycle was 12L/12D in all experiments. Lens Conditions: White light: Chicks wore binocular lenses for 4 hours in the morning (n=11) or evening (n=8) in white light (588 lux). Extra blue light: Chicks wore lenses for 4 hours in the evening, with the addition of 4 hours blue light (575 lux; 460 nm) in the morning (n=6). Control conditions: Blue light: chicks were exposed to 4 hours blue light (200 lux) in the morning (ZT0-ZT4; n=9) or evening (ZT8-ZT12; n=16). White light: chicks were not exposed to blue light (n=23). Growth rates (µm/9d) were determined using A-scan ultrasonography; rhythm parameters were determined by measures at 6-hr intervals over 24 hours on the last day of the experiment.

Results : Wearing lenses in the evening inhibited ocular growth relative to “white controls” (670 vs 766 µm/9d; ANOVA p=0.025; p<0.05); there was no significant effect of morning lens-wear (708 vs 766 µm/9d). The addition of blue light in the morning did not reduce the efficacy of the evening lens-wear: growth was inhibited relative both to white controls and to morning blue (no lens) controls (592 µm/9d vs 766 µm and 830 µm/9d respectively; p<0.05 for both comparisons). 4 hours of blue light in the evening (without lenses) increased the amplitude of the rhythm in choroidal thickness relative to white controls (71 µm vs 47 µm; p<0.05); wearing lenses in the evening prevented this effect (34 µm; p<0.01 for lens vs blue evening light).

Conclusions : The evening-wear of lenses that block light spectra in the circadian range inhibited eye growth in white light, and when “extra” blue light was added to the light cycle. These results suggest that such lenses may be beneficial in preventing the development of myopia in children.

This is a 2021 ARVO Annual Meeting abstract.