There has been an increase of attention towards the harmful effects of blue light from our phone screens, computers, and television exposure. But is the effect of these screens greater than the influence of our lifestyle? A recent article discovered that an increase in myopia (nearsightedness) and early developing vision problems can be attributed to lack of UV exposure from the sun (Williams et al., 2017). When weighing the effects of outdoor exposure and the effects on vitamin D metabolism, vitamin D has little to no effect and it was broad spectrum UV rays from the sun that had protective properties on developing eyes. To help understand the underlying mechanism, progressive myopia and hyperopia was measured in chickens exposed to different wavelengths of light (Foulds, Barathi & Luu, 2013). Red light was found to have caused progressive myopia, while blue light caused progressive hyperopia. When comparing this to humans, environments where humans are primarily exposed to artificial light correlates with worsening vision (i.e. schools, workplace, screen-time).
The purpose of these studies is to help stop the growing trend of worsening vision. There is a strong protection association with sun exposure during adolescence and carrying on through early adulthood (14-29 years old)(Williams et al., 2017). Wu et al. successfully measured a reduction in elementary aged students (7-11) by implementing a longer recess period during school in one cohort and maintained a normal schedule in another. Significant changes in myopia were measured in the students that did not receive an outdoor recess, confirming the impact of outdoor exposure (2013). Still, several mechanisms are left unexplained, but the evidence shows the effectiveness of natural sunlight and outdoor activities. Interventions are also much easier in most parts of the world and can have a lasting impact on ones vision that could help alleviate problems for years to come. As more studies are performed, more attention should be taken to look at the effects of less time spent in the classroom or workplace and more time spent outside.
References:
Williams KM, Bentham GCG, Young IS, et al. Association Between Myopia, Ultraviolet B Radiation Exposure, Serum Vitamin D Concentrations, and Genetic Polymorphisms in Vitamin D Metabolic Pathways in a Multicountry European Study. JAMA Ophthalmol. 2017;135(1):47–53. doi:10.1001/jamaophthalmol.2016.4752
Foulds WS, Barathi VA, Luu CD. Progressive myopia or hyperopia can be induced in chicks and reversed by manipulation of the chromaticity of ambient light. Invest Ophthalmol Vis Sci. 2013 Dec 9;54(13):8004-12. doi: 10.1167/iovs.13-12476. PMID: 24222304.
Wu PC, Tsai CL, Wu HL, Yang YH, Kuo HK. Outdoor activity during class recess reduces myopia onset and progression in school children. Ophthalmology. 2013 May;120(5):1080-5. doi: 10.1016/j.ophtha.2012.11.009. Epub 2013 Feb 22. PMID: 23462271.
There is also a separate theory that it is the fact that we are so close to books and screens all day that our eyes have adjusted by developing myopia. Computers are a very recent invention and have only been widely available since the 80s and 90s. However, wide-spread education has been available for much longer in the United States and literacy has been very high since the early 1900s. There is a link between this rise of literacy and the need for glasses. So, blue light causing myopia is not likely. More likely is time spent outside where children are not looking at things at a very close distance for long periods of time. It would be interesting to discover a difinitive cause, because if we know what causes myopia, we may be able to prevent it early on.
ReplyDeletehttps://www.psychologytoday.com/us/blog/pop-psych/201706/why-do-so-many-humans-need-glasses
Huang, H. M., Chang, D. S., & Wu, P. C. (2015). The Association between Near Work Activities and Myopia in Children-A Systematic Review and Meta-Analysis. PloS one, 10(10), e0140419. https://doi.org/10.1371/journal.pone.0140419