Association Between Myopia and UVB, Vitamin D Levels, or Genetics of Vitamin D Metabolism
JAMA Ophthalmology, January 2017
Spending time outdoors is known to protect against myopia, but it is not clear whether the primary reason is light intensity, ultraviolet radiation, serum vitamin D concentrations, or other factors. Williams et al. conducted a secondary analysis of the European Eye Study and found that of the factors above, only ultraviolet B (UVB) radiation exposure, particularly during adolescence and early adulthood, was associated with a reduced odds ratio (OR) for myopia.
Their study cohort (N = 3,168) was selected from a cross-sectional, population-based random sample of individuals 65 years of age and older; 371 participants had myopia, defined as a mean spherical equivalent of –0.75 D or worse. All participants received an eye exam, including refraction; provided a blood sample; and completed a comprehensive questionnaire on demographics, education, and other lifestyle factors. Of particular interest was the amount of time spent outdoors during daylight hours from age 14 years onward.
Vitamin D serum concentrations were measured using spectrometry and were adjusted by season. Data on vitamin D pathway single nucleotide polymorphisms (SNPs) were available for approximately one-third of the study population. Logistic regression was used to estimate ORs for myopia and UVB exposure, serum vitamin D concentrations, and vitamin D SNPs.
An increase in UVB exposure in the age groups of 14-19 and 20-29 years was associated with reduced odds for myopia. In keeping with earlier studies, the OR for myopia was significantly higher for the most-educated subset of participants. There was no evidence of a direct link between myopia and serum vitamin D concentrations or the genes involved in vitamin D metabolism. Unexpectedly, very high concentrations of plasma lutein appeared to correlate with reduced odds of myopia, a finding that warrants further investigation.
The authors concluded that exposure to UVB radiation between 14 and 29 years of age is associated with the greatest protection against myopia.
The original article can be found here.