Abstract
PurposeUltraviolet-B (UVB) light exposure is the major risk factor for developing a pterygium, and serum 25-hydroxyvitamin D (25(OH)D) level is an objective measure of UVB light exposure. In this study, we investigated the association between pterygium, sun exposure, and serum 25(OH)D.MethodsThis population-based, cross-sectional study comprised 12,258 adults (aged ≥19 years) participating in the fifth annual Korea National Health and Nutrition Examination Survey from 2010 to 2012. The enrolled subjects underwent interviews, clinical examinations, and laboratory investigations. The serum 25(OH)D levels were measured, and pterygium was examined by using a slit lamp. We used three adjusted logistic regression models and selected covariates as potential confounders.ResultsThe overall prevalence of pterygium was 7.09, and 53.1% of these subjects were women. The prevalence of pterygium was higher in elderly subjects and those who lived at low latitudes. In multivariate analysis with adjustment for confounding factors, subjects with a serum 25(OH)D level > 30 ng/mL, 25–30 ng/mL, and 15–20 ng/mL had an odds ratio (OR) (95% confidence interval [CI]) of 1.565 (1.035–2.366), 1.545 (1.086–2.198), 1.8 (1.358–2.386), and 1.535 (1.216–1.938), respectively, compared to those with a serum 25(OH)D level < 15 ng/mL. Subjects with a daily sun exposure > 5 h had an OR (95% CI) of 1.761 (1.395–2.223) compared to subjects with a daily sun exposure < 2 h.ConclusionThe present study provides epidemiological evidence of an association of daily sun exposure and serum 25(OH)D levels with pterygium in a representative Korean population.
Highlights
A pterygium is a fibrovascular growth of the conjunctiva, commonly encroaching onto the cornea [1]
12,258 participants aged ≥19 years were included in the analysis because this was the age group for which serum analyses were performed
All participants were Asian, and the iris color was brown to dark brown
Summary
A pterygium is a fibrovascular growth of the conjunctiva, commonly encroaching onto the cornea [1]. Altered limbal stem cells play a key role in the development of pterygium, and histopathological studies have revealed the role of chronic inflammation in its pathogenesis [4, 5]. The pathogenesis of pterygium formation remains unclear, one of the major demographic characteristics of pterygium is its strong link with geographical latitude, thought to be related to variations in ultraviolet-B (UVB) light exposure [6]. Epidemiological studies have revealed that the prevalence of pterygium is inversely related to latitude, and that it is greater among outdoor than indoor workers [7,8,9]. In previous studies, relatively subjective measurements of sunlight exposure with UVB irradiation were made based on surveys of outdoor job occupations, amount of leisure-time outdoor activities, and geographic location of residency [4, 10, 11]. Sun exposure has been accepted as a risk factor for
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