Light levels outdoors are above the brightness level required to prevent near/short sightedness, even with adequate sun protection measures in the form of sunglasses, wearing a hat or being in the shade

In July 2019 researchers from Singapore and Malaysia published the results of their study to assess the impact of shade, hat and sunglasses on the risk of near/short sightedness. It is known that a lack of time outdoors can potect against near/short sightedness therefore it is important to know the brightness levels required for outdoor programes to prevent near/short sightedness. A child-sized mannequin head was developed to measure brightness levels, with and without sun protection, across a wide range of environments in Singapore, outdoors (open park, under a tree, street) and indoors (under fluorescent lighting with a window, under white LED-based lighting without a window). A comparison was then made between indoor and outdoor brightness levels that are experienced while children are involved in day-to-day activities. Results showed that outdoor brightness levels were much higher (11,080-18,176 lux) than indoors (112-156 lux). In the shade, under a tree, the brightness levels were 5556-7876 lux and wearing a hat 4112-8156 lux. Wearing sunglasses produced a brightness level of between 1792-6800 lux which, although lower than being in the shade and whilst wearing a hat, were still 11-43 times higher than indoors. Recommendations on spending time outdoors to help prevent near/short sightedness whilst using adequate sun protection in the form of sunglasses, wearing a hat or being in the shade, can therefore be provided.

Lanca C et al. The Effects of Different Outdoor Environments, Sunglasses and Hats on Light Levels: Implications for Myopia Prevention. Transl Vis Sci Technol. 2019 Jul 18;8(4):7

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