Association Between Myopia, Ultraviolet B Radiation Exposure, Serum Vitamin D Concentrations, and Genetic Polymorphisms in Vitamin D Metabolic Pathways in a Multicountry European Study

Abstract

IMPORTANCE Myopia is becoming increasingly common globally and is associated with potentially sight-threatening complications. Spending time outdoors is protective, but the mechanism underlying this association is poorly understood. OBJECTIVE To examine the association of myopia with ultraviolet B radiation (UVB; directly associated with time outdoors and sunlight exposure), serum vitamin D concentrations, and vitamin D pathway genetic variants, adjusting for years in education. DESIGN, SETTING, AND PARTICIPANTSA cross-sectional, population-based random sample of participants 65 years and older was chosen from 6 study centers from the European Eye Study between November 6, 2000, to November 15, 2002. Of 4187 participants, 4166 attended an eye examination including refraction, gave a blood sample, and were interviewed by trained fieldworkers using a structured questionnaire. Myopia was defined as a mean spherical equivalent of −0.75 diopters or less. Exclusion criteria included aphakia, pseudophakia, late age-related macular degeneration, and vision impairment due to cataract, resulting in 371 participants with myopia and 2797 without.EXPOSURES Exposure to UVB estimated by combining meteorological and questionnaire data at different ages, single-nucleotide polymorphisms in vitamin D metabolic pathway genes, serum vitamin D 3 concentrations, and years of education.MAIN OUTCOMES AND MEASURES Odds ratios (ORs) of UVB, serum vitamin D 3 concentrations, vitamin D single-nucleotide polymorphisms, and myopia estimated from logistic regression.RESULT Of the included 3168 participants, the mean (SD) age was 72.4 (5) years, and 1456 (46.0%) were male. An SD increase in UVB exposure at age 14 to 19 years (OR, 0.81; 95% CI, 0.71-0.92) and 20 to 39 years (OR, 0.7; 95% CI, 0.62-0.93) was associated with a reduced adjusted OR of myopia; those in the highest tertile of years of education had twice the OR of myopia (OR, 2.08; 95% CI, 1.41-3.06). No independent associations between myopia and serum vitamin D 3 concentrations nor variants in genes associated with vitamin D metabolism were found. An unexpected finding was that the highest quintile of plasma lutein concentrations was associated with a reduced OR of myopia (OR, 0.57; 95% CI, 0.46-0.72). CONCLUSIONS AND RELEVANCEIncreased UVB exposure was associated with reduced myopia, particularly in adolescence and young adulthood. The association was not altered by adjusting for education. We found no convincing evidence for a direct role of vitamin D in myopia risk. The relationship between high plasma lutein concentrations and a lower risk of myopia requires replication.

Conjunctival ultraviolet autofluorescence area, but not intensity, is associated with myopia

“…Vitamin D 3 can be obtained in small amounts from diet but it is predominantly synthesised within the skin following ultraviolet‐B (UVB) light exposure, before being hydroxylated to 25‐hydroxyvitamin D 3 (25(OH)D 3 ), which is the metabolite quantified to determine the vitamin D status of an individual. Outcomes from recent studies exploring the association between vitamin D status and myopia fail to support an active, independent role for vitamin D in myopic eye growth regulation . While vitamin D status may be considered a useful objective biomarker of time spent outdoors, concentrations of 25(OH)D are influenced by a wide range of other factors, and sampling and measurement involves invasive procedures which are not routinely used in ophthalmic practice.…”

New Research Routes to Fight Myopia

“…Considering different dose of exposure to VL might also help to strength the potential relationship between the genetic factors and the anatomic changes, thus eventually strengthening the confirmatory evidence of such potential link. Furthermore, the results presented by the authors showing minor role of vitamin D in favor of shorter wavelength light exposure seem to provide a basis for the interpretation of a large scale study recently published by European researchers from a large scale study (Williams et al, 2017). …”

Mendelian randomisation and the goal of inferring causation from observational studies in the vision sciences

“…The other MR study examining risk factors for myopia provided evidence refuting a causal role for (low) serum vitamin D level in myopia development. This result implied that the association between serum vitamin D and refractive error observed in several cross‐sectional epidemiology studies is non‐causal, most likely mediated by the time individuals spend outdoors.…”