The current knowledge about the impact of light on myopia development is extensive:

Light Intensity and Outdoor Exposure

Outdoor light exposure has been consistently linked to a reduced risk of myopia onset and progression in children. This protective effect is primarily attributed to:

• Higher light intensity outdoors (10,000-100,000+ lux) compared to indoor environments (10-1000 lux)
• Increased duration of exposure to natural light

Studies have shown:

• A dose-response relationship between outdoor exposure time and reduced myopia risk
• 2-5% reduced odds of prevalent myopia and 24-46% reduction in relative risk of incident myopia for every additional hour of outdoor time per week

Light Wavelengths

Different light wavelengths appear to have varying effects on myopia development:

• Blue light: Tends to inhibit myopia development and suppress axial eye growth
• Red light: Some studies suggest it may promote myopia, while others indicate a potential protective effect
• Violet light (360-400 nm): Shown to suppress axial elongation in both animal models and humans

Mechanisms of Action

The protective effects of light on myopia are thought to work through several mechanisms:

• Retinal dopamine secretion: Affected by both light intensity and wavelength
• Activation of rod pathways: Dim light exposure may play a role in myopia development
• OPN5 (neuropsin) protein: A photoreceptor protein sensitive to violet light that appears crucial in stopping myopia progression

Time of Day

The timing of light exposure may be important:

• Evening hours seem to be most effective for violet light treatment in animal studies

Other Factors

Several other light-related factors may influence myopia:

• Spectral composition of light affects emmetropization and myopia development
• Circadian rhythm and sleep patterns may be involved in the light-myopia relationship
• Seasonal variations in daylight hours affect myopic progression, with slower axial length growth during summer months

Emerging Treatments

Recent research has explored potential light-based treatments:

• Red light therapy: Some studies show promise in slowing axial elongation in school-aged children with myopia
• High-intensity light exposure: Shown to reduce experimental myopia in animal models

Practical Implications

Current recommendations suggest:

• At least two hours of daily outdoor light exposure for children and adolescents
• Increasing ambient light levels in indoor environments, particularly in schools

While understanding of light’s impact on myopia has grown significantly, many questions remain. Ongoing research continues to explore the complex interplay between light exposure, environmental factors, and myopia development.

Sources:

https://pmc.ncbi.nlm.nih.gov/articles/PMC9114237/

https://iovs.arvojournals.org/article.aspx?articleid=2705915

https://bme.gatech.edu/bme/news/understanding-how-violet-light-can-stop-myopia-progression

https://jphysiolanthropol.biomedcentral.com/articles/10.1186/s40101-024-00354-7

https://clspectrum.com/issues/2023/may/lighting-the-way-to-myopia-control/

https://journals.lww.com/tjop/fulltext/2024/14020/the_impact_of_light_properties_on_ocular_growth.2.aspx?context=latestarticles

https://reviewofmm.com/light-and-myopia/

https://reviewofmm.com/role-of-light-exposure-in-myopia-management/

David Shiller

David Shiller is the Publisher of LightNOW, and President of Lighting Solution Development, a North American consulting firm providing business development services to advanced lighting manufacturers. The ALA awarded David the Pillar of the Industry Award. David has co-chaired ALA’s Engineering Committee since 2010. David established MaxLite’s OEM component sales into a multi-million dollar division. He invented GU24 lamps while leading ENERGY STAR lighting programs for the US EPA. David has been published in leading lighting publications, including LD+A, enLIGHTenment Magazine, LEDs Magazine, and more.

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