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

Abstract

Myopia results from an excessive axial growth of the eye, causing abnormal projection of remote images in front of the retina. Without adequate interventions, myopia is forecasted to affect 50% of the world population by 2050. Exposure to outdoor light plays a critical role in preventing myopia in children, possibly through the brightness and blue-shifted spectral composition of sunlight, which lacks in artificial indoor lighting. Here, we evaluated the impact of moderate levels of ambient standard white (SW: 233.1 lux, 3900 K) and blue-enriched white (BEW: 223.8 lux, 9700 K) lights on ocular growth and metabolomics in a chicken-model of form-deprivation myopia. Compared to SW light, BEW light decreased aberrant ocular axial elongation and accelerated recovery from form-deprivation. Furthermore, the metabolomic profiles in the vitreous and retinas of recovering form-deprived eyes were distinct from control eyes and were dependent on the spectral content of ambient light. For instance, exposure to BEW light was associated with deep lipid remodeling and metabolic changes related to energy production, cell proliferation, collagen turnover and nitric oxide metabolism. This study provides new insight on light-dependent modulations in ocular growth and metabolomics. If replicable in humans, our findings open new potential avenues for spectrally-tailored light-therapy strategies for myopia.

Recovery From Form-Deprivation Myopia in Chicks Is Dependent Upon the Fullness and Correlated Color Temperature of the Light Spectrum

“…1 B), promoted a recovery from myopic refractive error to measures that were not significantly different from control eyes on D28 of the experimental protocol. Previous reports have also shown that blue-enriched white light (CCT = 9700 K) can slow axial elongation induced by FDM, and accelerate recovery from FDM in a chicken model, 26 whereas a recent study by Yoon et al 36 demonstrated that exposure to 985 lux of broad-spectrum light with a high blue content can slow axial elongation in chicks. Whether the effect of blue-enriched white light on recovery from experimental myopia is only due to LCA 46 or other additional phenomena remains unclear.…”

“… 30 Although many investigations have focused on the impact of intense light on experimental myopia development, 31 – 35 only a few have investigated the impact of the spectral characteristics of ambient, moderate intensity, visible white light on refractive error development. 15 , 26 , 36 …”

“…resting refraction) with no accommodative changes was calculated from the continuous refraction trace over time in each animal's eye. Ocular AL, choroidal and retinal thicknesses, and anterior chamber depth (ACD) were measured in all animals on D1, D7, D14, D22, and D28 following protocols described by Najjar et al 26 The AL was defined as the distance between the echo spike corresponding to the anterior surface of the cornea and most anterior spike originating from the retina, and this was measured via A-scan ultrasonography using a PacScan Plus (Sonomed Escalon, New Hyde Park, NY, USA) at 10 MHz frequency. The median of at least five scans was calculated per eye for each animal.…”

Light and myopia: from epidemiological studies to neurobiological mechanisms

“…130–132 Furthermore, ocular DA release and metabolism, as well as vitreal and retinal metabolomic profiles, were highly dependent upon the spectral composition of light. 132,133 Among plausible explanations to this wavelength-dependent refractive error regulation, ocular longitudinal chromatic aberration (LCA), which leads to wavelength defocus and higher refraction of short-wavelength light compared with long-wavelength light by ocular optics, was supported by many authors. 131,134,135 The hyperopic shift in response to short-wavelength blue light has also been reported in other, but not all, animal species such as Cichlid fish, 136 guinea pigs 137–141 and some rhesus monkeys.…”

“…sleep, alertness, melatonin secretion at night) (for review, see Najjar and Zeitzer 231 ). Melanopsin is predominantly sensitive to bright blue light (~480nm), a wavelength reported to induce hyperopia and reverse experimental myopia in some animal models 130–133 and the increase in ocular DA levels upon bright light exposure could potentially be due to the stimulation of melanopsin and the synaptic and functional connection between the ipRGCs and dopaminergic amacrine cells. 232,233 In addition, melanopsin knockout mice display a decline in ocular DA levels, 234 and preliminary findings highlight a direct, yet unclear, role of melanopsin in refractive error development.…”