Ocular growth and metabolomics are dependent upon the spectral content of white light

Abstract

Purpose : To evaluate the impact of blue-enriched white light on ocular growth and metabolomics signature of the vitreous and retina in a chicken model of form-deprivation myopia.

Methods : Thirty-six chicks (Lohmann brown strain) were randomly assigned into 2 groups of 18 animals each. Animals were housed for 28 days in a light-tight enclosure under a 12/12h light/dark cycle of isoluminant (~220 lux) blue-deprived (BD) 3900K, or blue-enriched (BE) 9700K white light. Myopia was induced monocularly in all chicks by random occlusion of one eye with a frosted diffuser from day 1 post-hatching (D1) until D14. Ocular axial length (AxL) was measured using ultrasonography on days 1, 7, 14, 22 and 28, and compared between groups and eyes using a 2-way repeated measures ANOVA. Histological choroid thickness measurements were performed on D28. Targeted metabolomics analyses of vitreous and retinas were performed using Biocrates AbsoulteIDQ kit. Multivariate statistical analysis was carried out using non-supervised [PCA] and supervised [PLS-DA] projection methods. Data are presented as mean ± standard deviation.

Results : After 14 days of form-deprivation, AxL was increased in form-deprived (Fdep) eyes compared to control (Ctrl) eyes in both groups (P<0.001). Animals raised under BE light showed a reduced AxL increase in Fdep eyes (10.0±0.5 mm) compared to animals raised under BD light (10.6±0.4 mm) (P<0.05). Two weeks following form-deprivation (D28), the AxL of Fdep eyes was no longer different from Ctrl eyes in chicks raised under BE light (P=0.2) but not in those raised under BD light. Preliminary histological findings show that eyes exposed to BE light had thicker choroids (n=4; Ctrl: 219.2±69.3 µm; Fdep: 528.0±196.4 µm) compared to eyes exposed to BD light (n=6; Ctrl: 122.3±44.9 µm; Fdep: 277.8±199.4 µm). The metabolomics signature in the vitreous and retinas of Ctrl and Fdep eyes was highly dependent upon the chromaticity of the light exposure (AUROC range: 0.85-0.88; P<0.05), and was different between Ctrl and Fdep eyes. These signatures involved a deep lipid remodeling in the vitreous and retina.

Conclusions : Moderate intensities of blue-enriched white light can increase choroid thickness, slow axial elongation and accelerate recovery from ametropia in a chicken model of myopia. Moreover, the chromaticity of ambient light can modify the metabolomic signature of the vitreous and retinas in healthy and form-deprived eyes.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.