title: Prevalence of dry eye disease in Mongolians at high altitude in China: the Henan eye study.
abstract: OBJECTIVE
  To estimate the prevalence of dry eye disease, analyze the associations between dry eye symptoms and signs, and identify the risk factors in an elderly Mongolian population at high altitude in China.
  
  
  METHODS
  A population-based survey was conducted in 2006. A total of 2,486 Mongolians age 40 and older were selected. Symptoms of dry eye were assessed using a 6-item validated questionnaire. Dry eye disease was defined if participants reported one or more symptoms often or all the time. Positive signs included a tear-film breakup time of <or=10 seconds, a Schirmer test score of <or= 5 mm, or a fluorescein staining score >or= 1 in one or both eyes. Presence of dry eye symptoms and positive signs were analyzed. Correlations between symptoms and signs, and risk factors were evaluated in a multivariate model.
  
  
  RESULTS
  Of the 1,816 participants, 50.1% (95% confidence interval, 47.8-52.4) were symptomatic. Tear-film breakup time of </= 10 seconds was 37.7% (95% confidence interval, 35.5-39.9). A Schirmer test score of <or= 5 mm was 19.9% (95% confidence interval, 18.4-22.1). Fluorescein staining score >or= 1 was 6.0% (95% confidence interval, 4.9-7.1). The correlation between dry eye symptoms and positive signs (tear-film breakup time of <or= 10 seconds[r = 0.414, P < 0.001], Schirmer test score of <or= 5 mm [r = 0.164, P = 0.001], and fluorescein staining score >or=1 [r = 0.361, P < 0.001]) were statistically significant. Independent risk factors included increased age, age-related cataract and pterygium.
  
  
  CONCLUSIONS
  This study demonstrates a high prevalence rate of dry eye disease in a Mongolian population. Dry eye signs were significantly associated with dry eye symptoms.
authors.affiliation: West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Guo
authors.forename: Peng
authors.initials: P
authors.lastname: Lu
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Chen
authors.forename: Wenfang
authors.initials: W
authors.lastname: Zhang
authors.forename: Rongting
authors.initials: R
authors.lastname: Chen
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000532:Altitude Sickness / Q000175:diagnosis / Q000208:ethnology*; D044466:Asian People; D002681:China / Q000453:epidemiology; D015352:Dry Eye Syndromes / Q000175:diagnosis / Q000208:ethnology*; D005260:Female; D015590:Fluorophotometry; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution; D011795:Surveys and Questionnaires