Are higher blood mercury levels associated with dry eye symptoms in adult Koreans? A population-based cross-sectional study.
OBJECTIVE
The purpose of this study was to investigate whether blood mercury concentrations associated with the presence of dry eye symptoms in a nationally representative Korean population.


METHODS
Population-based prospective cross-sectional study using the heavy metal data set of the 2010-2012 Korean National Health and Nutrition Examination Survey (KNHANES). A total of 4761 adult Koreans were the eligible population in this study. Of the 7162 survey participants, 2401 were excluded because they were <19 years of age, there were missing data in the heavy metal data set, or they had diabetes, rheumatoid arthritis, thyroid disease, asthma, depression and/or under-the-eye surgery. Blood mercury levels were measured on the day the participants completed a questionnaire regarding the presence of dry eye symptoms (persistent dryness or eye irritation). The population was divided into low and high groups by median level (4.26 and 2.89 µg/L for males and females, respectively).


RESULTS
Self-reported dry eye symptoms were present in 13.0% of the cohort. Participants with dry eye symptoms were significantly more likely to have blood mercury levels exceeding the median than those without dry eye symptoms (45.7% vs 51.7%, p=0.021). Logistic regression analysis showed that, after adjusting for age, gender, education, total household income, smoking status, heavy alcohol use, sleep time, perceived stress status, total cholesterol levels and atopy history, dry eye symptoms were significantly associated with blood mercury levels that exceeded the median (reference: lower mercury group; OR, 1.324; 95% CI 1.059 to 1.655; p<0.05).


CONCLUSIONS
High blood mercury levels were associated with dry eye symptoms in a nationally representative Korean population.
Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, and Catholic Institute for Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
So-Hyang
SH
Chung
Department of Occupational and Environmental Medicine, Center for Occupational and Environmental Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Jun-Pyo
http://orcid.org/0000-0001-8674-1034
JP
Myong
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D015352:Dry Eye Syndromes / Q000097:blood* / Q000209:etiology; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005123:Eye / Q000187:drug effects / Q000473:pathology*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008628:Mercury / Q000009:adverse effects / Q000097:blood*; D008875:Middle Aged; D011446:Prospective Studies; D056910:Republic of Korea; D057566:Self Report; D011795:Surveys and Questionnaires; D055815:Young Adult
D008628:Mercury
Blood mercury; Dry eye; Korean National Health and Nutrition Examination Survey; PUBLIC HEALTH