Aims To determine the prevalence and identify associated risk factors for pterygium in an elderly Mongolian population at high altitude in Henan County, China. Methods A population-based survey was conducted from June 2006 to September 2006. A stratified, clustered, random sampling procedure was used to select 2486 Mongolian people aged 40 years and older. Pterygium was diagnosed and graded clinically as grade 1 (transparent), 2 (intermediate), and 3 (opaque). Risk factors associated with pterygium were evaluated with logistic regression models. Results From 2486 eligible subjects, 2112 (84.9%) were examined. There were 378 people with either unilateral (n ¼ 228) or bilateral (n ¼ 150) pterygia, equivalent to an overall prevalence of 17.9% (95% confidence interval (CI) 16.3, 19.5). The prevalence increased with older age (v 2 -test of trend Po0.001). Visual acuity decreased with higher group of pterygium (v 2 ¼ 97.759, Po0.0001). Pterygium was independently associated with Schirmer's test (p5 mm) (odds ratio (OR) 2.4; 95% CI, 1.9, 3.1), tear breakup time (p10 s) (OR 2.3; 95% CI, 1.8, 2.9), lower education level (o3 years) (OR 2.1; 95% CI, 1.4, 3.2), increasing age (OR 2.0; 95% CI, 1.4, 2.8) for persons 70-79, compared with 40-49, and other risk factors. Conclusions The prevalence of pterygium in an older Mongolian population at high altitude is high, primarily because of ocular sun exposure and the other effects of the unique plateau climate, and representing an important health problem. People should be strongly encouraged to wear a wide-brimmed hat and/or sunglasses whenever they are outside.

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Environmental pollutants could be implicated in the cause of female infertility beyond traditional factors. Until now, no study has focused on the association of environmental exposure to aldehydes with female infertility. This study intended to investigate the possible impact of serum levels of aldehyde on female infertility. A cross-sectional study was performed on 516 nationally representative participants from 2013 to 2014 National Health and Nutrition Examination Survey (NHANES) in US. Multivariate logistic regression models and restricted cubic splines were used to examine the association between serum levels of aldehydes and the risk of female infertility. Women in the highest tertile of exposure to benzaldehyde had a 66% (odds ratio [OR] = 0.34, 95% confidence interval [CI] = 0.14–0.79) lower risk of infertility compared to those in the lowest tertile, after adjusting for other variables. Restricted cubic spline indicated a linear and negative association of benzaldehyde with female infertility (p for nonlinearity = 0.74), while other aldehydes did not exhibit a significant correlation. In summary, this cross-sectional study indicates that higher benzaldehyde level correlated with a lower rate of female infertility, which could help guide future research and contribute to the development of interventions to prevent or treat infertility and improve reproductive health outcomes.