Optimizing the lighting environment for better myopia-control

Myopia is a highly prevalent refractive error characterized by the blurred vision of objects when viewed at a distance. Myopia is projected to affect 50% of the world population by 2050 and is commonly due to excessive ocular axial growth leading to images being focused in front of the retina. Myopia is far more than an inconvenience and is associated with vision threatening ocular complications, such as glaucoma, retinal detachment, and neo-vascularisation. Epidemiological studies have shown that time spent outdoors is protective against myopia. This could be due to the increased brightness and unique spectral characteristics of sunlight that are generally lacking indoors. The Eye N’ Brain team is conducting research in animal models and humans to better understand the neurobiology behind light-driven myopia-control and develop tailored light therapy strategies for myopia prevention.

The Neurobiology of Photic Interventions for Myopia-Control

We have recently developed a state-of-the-art research facility for evaluating the impact of light (intensity, spectrum, timing and duration) on different animal models including chickens, guinea pigs, and non-human primate (NHP). The NHP model includes Rhesus and Cynomolgus Macaques and was successfully developed in collaboration with Professor Earl Smith and Dr Li-Fang Hung (University of Houston, USA) using custom-built 3D-printed helmets equipped unilaterally with a Bangerter occlusion foil. We are currently using this model to evaluate the chronic impact of intermittent high intensity light exposures on ocular growth, myopia development and ocular vasculature and structure using swept-source optical coherence tomography-angiography. Intermittent exposure to high intensity light is showing promising results in preventing the onset of myopia in NHPs. Our team is also investigating 1/ the synergetic impact of defocus interruption and high intensity light and 2/ the impact of spectrally tailored indoor lighting strategies on emmetropization and ocular growth and metabolomics in chicken models of form-deprivation and lens-induced myopia. The ultimate goal of the group is to translate findings in animal models into feasible light therapy strategies for myopia prevention. These projects are in collaboration with the departments of Myopia (Co-Heads: Prof Saw Seang Mei, A/Prof Audrey Chia), Ocular Imaging (Head: Prof Leopold Schmetterer), Ophthalmic Engineering (Head: A/Prof Michael Girard), and the Translational Preclinical Model Platform (Head A/Prof Veluchamy Amutha Barathi) at the Singapore Eye Research Institute (SERI).

Figure from Muralidharan et al. 2021

Recent Findings:

We have recently reported that the spectral composition of white light can affect ocular growth and metabolomics. In a work published in Scientific Reports (Najjar et al. 2021) 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 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.

Building on these endeavors, our group is currently focusing on uncovering the signaling pathway from the retina to the sclera through the utilization of biomechanical analyses, transcriptomics, proteomics, and metabolomics.