By Marc Sorenson, EdD, Sunlight Institute…
Several scientific investigations have linked sunlight deprivation to nearsightedness (myopia), and many of these have been discussed on previous blogs. The latest used rhesus monkeys as subjects.[i] These monkeys were reared either with natural lighting for three hours daily or indoor lighting. As we might expect, those that were raised with indoor lighting developed myopia, whereas those raised with natural lighting did not develop the disorder. The eye dimensions became abnormal in the monkeys that were exposed only to indoor light, and problems with refraction, due to eye elongation, were noted.
There is no doubt that sun deprivation is a factor that leads to blindness. Others obviously feel the same way. Here I quote from Dr. Hobday, writing in Perspectives of Public Health: “A century ago, it was widely believed that high levels of daylight in classrooms could prevent myopia, and as such, education departments built schools with large windows to try to stop children from becoming short-sighted. This practice continued until the 1960s, from which time myopia was believed to be an inherited condition. In the years that followed, less emphasis was placed on preventing myopia. It has since become more common, reaching epidemic levels in East Asia. Recent research strongly suggests that the amount of light children get as they grow determines whether they will develop short sight; however, evidence that daylight in classrooms prevents myopia is lacking. Given the rapid increase in prevalence among school children worldwide, this should be investigated.”[ii]
Others are also concerned and state that eye elongation and progression of myopia decrease in periods with longer days and to increase in periods with shorter days.[iii] According to these researchers, “children should be encouraged to spend more time outside during daytime to prevent myopia.”
[i] Wang Y, Ding H, Stell WK, Liu L, Li S, Liu H, Zhong X. Exposure to sunlight reduces the risk of myopia in rhesus monkeys. PLoS One. 2015 Jun 1;10(6).
[ii] Hobday R. Myopia and daylight in schools: a neglected aspect of public health? Perspect Public Health 2015 Mar 23.
[iii] Cui D, Trier K, Munk Ribel-Madsen S. Effect of day length on eye growth, myopia progression, and change of corneal power in myopic children. Ophthalmology. 2013 May; 120(5):1074-9