I am fascinated by the interactive relationship between light and the eye, both in image formation for sight and the effect on eye health. Recently, I researched the link between light and high myopia, a progressive disease that has reached epidemic proportions globally and can lead to retinal complications with the potential to cause loss of sight.
One of the areas being studied for its potential contribution to high myopia progression in children is time spent outdoors in sunlight, or I should say the lack of enough time in sunlight. I was curious which wavelengths of sunlight conferred the benefit of slowing eye elongation and the progression to high myopia. According to Williams KM, Bentham GCG, Young IS, et al., “Significant odds ratio for less myopia with increased UVB exposure were observed in adolescence and early adulthood, between ages 14 to 19 years and 20 to 29 years but not for other age groups.” (Association Between Myopia, Ultraviolet B Radiation Exposure, Serum Vitamin D Concentrations, and Genetic Polymorphisms in Vitamin D Metabolic Pathways in a Multicountry European Study.) While the study relied on the memory of subjects, those reporting a higher annual lifetime of UVB exposure in their youth through their 20s had lower occurrence of high myopia. The authors of the study cite the findings of a meta-analysis of seven cross-sectional studies found for every additional hour of time spent outdoors per week increased the odds of myopia by 2 percent. The authors of this study state, “As the protective effect of time spent outdoors is increasingly used in clinical interventions, a greater understanding of the mechanisms and life stages at which benefit is conferred is warranted.”
I have spent years promoting UVR protection in children to reduce the risk of cataract and AMD later in life and now the above research showed early life exposure to sunlight particularly UVB may be linked to lower incidence of myopia progression in the young. Interestingly, children have a window of exposure to UVA and UVB light which eyes age 34 and older don’t have. “A young lens transmits 300 – 340 in UV range max 8% 320nm.” (Age-Related Changes in the Absorption Characteristics of the Primate Lens, Elizabeth R. Gaillard, et al.) Wavelengths aside, the important thing to remember is that it is outdoor time in sunlight that is being used by eyecare professionals to lower the risk of high myopia progression in the young. I am not an expert; I make no recommendations and only report the results of the above referenced study.
• Deborah Kotob
Pro to Pro Director