Optician India

As urbanization increases, myopia is rapidly spreading among children, regardless of screen time. Attention has shifted from optical explanations to neurochemical factors like dopamine, now recognized as ‘Hero‘- a key protective signal in myopia control. Beyond its role in reward pathways, dopamine regulates postnatal eye development and axial growth.1

Outdoor exposure is a major, often overlooked, protective factor against myopia. Studies show children exposed to intense natural light have lower myopia risk, even with high near work.2 While indoor lighting is only a few hundred lux, sunlight ranges from 10,000 to 100,000 lux.3 Sunlight’s broad spectrum is also important: violet light (VL, 360–400 nm), recently studied, suppresses axial elongation in myopic mice via the nonvisual opsin OPN5, also present in humans.4 However, most artificial lights emit no VL, and window glass blocks both violet and ultraviolet light, so indoor environments lack VL exposure.5,4

Dopamine acts as STOP signal for ocular growth. Increased dopamine release influences downstream ocular tissues—including the retina, choroid, and sclera—by modulating extracellular matrix remodeling and ocular biomechanics, whereas reduced dopamine levels are associated with form-deprivation and lens-induced myopia. Wavelength of Light beside intensity also regulates dopamine. In recent discoveries in animals, it has revealed that VL activates opsin 5 (OPN5) in retinal ganglion cell, regulating dopamine availability during early postnatal development. 6 Though direct evidence linking OPN5 to human myopia is still in progress, this concept of early light exposure directs long term eye growth trajectories through dopamine signaling.7

Dopamine signaling is different in natural and artificial lights. The full spectrum, dynamic, circadian aligned stimulus  promotes sustained retinal dopamine release whereas indoor lightening and digital screens elicits brief, phasic dopamine responses connected to visual attention and reward do not confer the equal protective effects against axial elongation.8,9 This differentiation often explains why screen exposure does not duplicate the advantages of outdoor light, despite visual stimulation.

Figure1: Dopamine & Ocular Growth Regulators( AI )

Nowadays, repeated low level red light (RLRL) therapy has crucial role in intervention of myopa control. It enhances mitochondrial function via cytochrome c oxidase, increases choroidal thickness, and improves retinal metabolism irrevelant to the doamine pathway.10 RLRL may indirectly promote dopamine-regulated growth regulation by enhancing retinal health. It is still a therapeutic alternative, and cannot replace the sunlight's biological benefits.11

Dopamine is a master regulator of axial development rather than just a neurotransmitter and also signals pertaining to light intensity, spectral composition, circadian timing, and total retinal activity promoting normal eye growth. .12 Crucially, new research indicates that  young children who are well-nourished and absence of  myopia family history may still be at risk if they are not exposed to enough sunshine during crucial developmental stages.13

According to this viewpoint, myopia is no longer only a refractive error but  a  disordered developmental signaling, one that is being influenced more by contemporary urban lifestyles that involve less exposure to natural light and changed circadian rhythms.14

Keywords:
Dopamine, Light, Myopia control

References

1. Feldkaemper, M., & Schaeffel, F. (2013). Mechanisms of myopia development and potential targets for treatment. Progress in Retinal and Eye Research, 37, 75–115. https://doi.org/10.1016/j.preteyeres.2013.02.002
2. Rose, K. A., Morgan, I. G., Ip, J., Kifley, A., Huynh, S., Smith, W., & Mitchell, P. (2008). Outdoor activity reduces the prevalence of myopia in children. Ophthalmology, 115(8), 1279–1285. https://doi.org/10.1016/j.ophtha.2007.12.019
3. He, X., et al. (2022). Time outdoors in reducing myopia: A school-based cluster randomized trial with objective monitoring of outdoor time and light intensity. Ophthalmology, 129(11), 1245–1254. https://doi.org/10.1016/j.ophtha.2022.06.024
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5. Chen, J., et al. (2024). Smartwatch measures of outdoor exposure and myopia in children. JAMA Network Open, 7, e2424595. https://doi.org/10.1001/jamanetworkopen.2024.24595
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9. Li, Z., Zhang, Y., Chen, W., Zhang, Y., Xu, W., & Mu, G. (2025). Peripheral retinal irradiation with low-energy red light can effectively and safely delay the progression of myopia. BMJ Open Ophthalmology, 10(1), e001895. https://doi.org/10.1136/bmjophth-2024-001895
10. Xue, F., & Zhou, Y. (2025). Illuminating eye care: The promise and future of red light therapy in ophthalmology. Graefe’s Archive for Clinical and Experimental Ophthalmology, 263(6), 1515–1522. https://doi.org/10.1007/s00417-025-06800-1
11. Chen, Q., Wei, H., Soh, Z. D., Zhu, Q., Shao, X., Xue, C., et al. (2025). The effectiveness of red-light therapy on myopia control depends on its direct effect: A mediation analysis. Journal of Translational Medicine. https://doi.org/10.1186/s12967-025-07514-y
12. Huang, L., Zhang, D., & Zhou, J. (2025). Myopia development: Multifactorial interplay, molecular mechanisms and possible strategies. Frontiers in Medicine. https://doi.org/10.3389/fmed.2025.1638184
13. Landis, E. G., Park, H. N., Chrenek, M., He, L., Sidhu, C., Chakraborty, R., Strickland, R., Iuvone, P. M., & Pardue, M. T. (2021). Ambient light regulates retinal dopamine signaling and myopia susceptibility. Investigative Ophthalmology & Visual Science, 62(1), 28.
14. An analysis of light that reaches the eye surface in an outdoor environment. (2025). Scientific Reports. https://doi.org/10.1038/s41598-025-16592-3