Sunlight and its effect on eye health
Longer wavelength ultraviolet light may actually prevent myopia
Times are changing as we become obsessed with the 24/7 proliferation of blue light-emitting LEDs. The U.S. public health authorities are cautioning against sunlight exposure, yet growing members of the scientific community are recognizing the preventive and therapeutic aspects of ocular and dermal (non-burning) natural sunlight exposure. 1
Avoiding sunlight entirely appears to be misdirected. Melanoma is in fact inversely related to latitude and inadequate acclimation (i.e., increased melanization and epidermal thickening), which carries the risk of melanoma and non-melanoma skin cancer—both common in northern latitudes.
The principal non-genetic melanoma risk is excessive and cumulative ultraviolet (UV) radiation. The relationship between melanoma and UV is two-sided: non-burning sun exposure is associated with a reduced risk of melanoma, while sunburns are associated with a doubling of risk.1, 2
Previously from Dr. Richer: OD education must keep up with industry changes
Internal skin protection against melanoma and non-melanoma skin cancer with dietary vitamin D3, carotenoids lycopene, and secondarily lutein and zeaxanthin are underutilized strategies.3 While 1,500 patients die each year from skin cancer, 1,500 patients die each day from other cancers and vitamin D-related chronic diseases according to John Cannell, MD of the Vitamin D Council (https://www.vitamindcouncil.org) and augmented by a recent meta-analysis .4 Vitamin D from UV B (290nm to 315nm) sunlight exposure (and diet/supplements) is key to cancer prevention.
Light effects on myopia
The global epidemic of myopia is upon us—especially in Southeastern Asia where juvenile myopia is an epidemic.5 According to the National Eye Institute, Caucasian American children saw an increase between 25 to 41 percent in myopia between 1971 and 2004. African-American children saw an increase of 157 percent during the same span.1, 6
Factors involved are bioenvironmental, with recent epidemiological evidence suggesting children who spend more time outdoors (in intense light) are less likely to be or become myopic—regardless of their near work or whether their parents are myopic.7 One likely mechanism for this protective effect is visible light-stimulating release of dopamine from the retina. This inhibits increased axial elongation, the structural basis of myopia.