Abstract
Purpose :
To investigate the impact of morning and afternoon exposure to brief, moderate-level, intermittent full-spectrum light on form-deprivation (FD) myopia in chickens.
Methods :
One-day old chicks (n=18) were equally assigned to 3 groups. All groups were raised under standard control light (CL, 500 lux, 7am-7pm, 4000K). Two groups were additionally exposed to full-spectrum LEDs (i.e., mimicking sunlight) for 2h/day intermittently (IL:0.5h of 1000 lux [4000K] every 1.5h of CL), starting from either 8am to 2:30pm (IL-AM) or 12pm to 6:30pm (IL-PM). FD was induced in all chicks by random occlusion of one eye (FD eye) with a frosted diffuser from day one (D1) until D8. At D8, diffusers were removed and recovery from FD was monitored until D15. Refraction, axial length (AL) and choroidal thickness, were respectively recorded using infra-red photorefraction, ultrasonography and posterior optical coherence tomography on D1, D8 and D15. Data were expressed as intra-ocular difference (IOD=FD-control eye) and compared using a 2-way ANOVA and a pairwise multiple comparison procedure using Holm-Sidak.
Results :
At the end of FD(D8), IOD in refraction was attenuated (i.e.,FD eye less myopic) by both IL protocols (IL-AM:-7.29±0.48D; IL-PM:-5.11±0.69D, P<0.01) compared to CL (-9.29±1.05D). In addition, IL-PM was more effective than IL-AM in reducing myopic refraction (P=0.01,Fig 1A). Similarly, IOD in AL of IL-PM was significantly reduced compared to CL (P=0.001). On D15, both IL protocols had reduced IOD in refraction and AL compared to CL (P<0.01), while myopic refraction, but not AL, IL-PM was significantly reduced compared to IL-AM (P<0.05)(Fig 1A, B). No significant difference in the choroidal thickness were noted between groups(Fig 1C).
Conclusions :
Our preliminary findings suggest that intermittent exposure to moderate levels (1000 lux) of full-spectrum LED light can slow the development of and accelerate recovery from FD myopia. Afternoon exposure to intermittent light may be more effective than morning exposure for myopia prevention.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.