title: Ethnic Variations in Pterygium in a Rural Population in Southwestern China: The Yunnan Minority Eye Studies.
abstract: OBJECTIVE
  To determine the prevalence and associations of pterygium in a multiethnic adult population in rural China and to examine potential ethnic differences Methods: A total of 6418 adults (2133 ethnic Bai, 2130 ethnic Yi, and 2155 ethnic Han) aged 50 years or older participated in the study. Anterior segment examination was performed without pupil dilation using a slit lamp. Pterygium was deﬁned as a raised ﬂeshy triangular ﬁbrovascular tissue growth of the conjunctiva encroaching onto a clear cornea.
  
  
  RESULTS
  Pterygium was least prevalent among adults of Yi ethnicity (29.5%) compared with Bai (39.0%, p < 0.001) or Han (39.5%, p < 0.001) ethnicities. Those of Bai ethnicity were most likely to be affected by severe pterygium (7.5%), while Yi were least likely to be affected (3.8%). Multivariate analysis revealed that increasing age (odds ratio, OR, 1.017), female sex (OR 1.53), lower educational level (OR 1.25), higher blood pressure levels (OR 1.002), and greater time spent outdoors per day (OR 1.09) were significantly associated with a higher prevalence of pterygium, while Yi ethnicity (OR 0.65, comparing Yi with Han) and wearing brimmed hats outdoors (OR 0.82) were protective factors.
  
  
  CONCLUSIONS
  Ethnicity was significantly associated with prevalence of pterygium. Our findings may be applicable to many other countries located within the "pterygium belt" for health resource allocation among different ethnic groups.
authors.affiliation: a The First Affiliated Hospital of Kunming Medical University , Kunming , China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhong
authors.affiliation: b First Affiliated Hospital of Nanjing Medical University , Nanjing , China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Chen
authors.affiliation: a The First Affiliated Hospital of Kunming Medical University , Kunming , China.|c The Second People's Hospital of Yunnan Province , Kunming , China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: a The First Affiliated Hospital of Kunming Medical University , Kunming , China.|c The Second People's Hospital of Yunnan Province , Kunming , China.
authors.forename: Wei
authors.initials: W
authors.lastname: Shen
authors.affiliation: d Kunming Medical University , Kunming , China.
authors.forename: Xun
authors.initials: X
authors.lastname: Sheng
authors.affiliation: a The First Affiliated Hospital of Kunming Medical University , Kunming , China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Niu
authors.affiliation: a The First Affiliated Hospital of Kunming Medical University , Kunming , China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhou
authors.affiliation: d Kunming Medical University , Kunming , China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wei
authors.affiliation: a The First Affiliated Hospital of Kunming Medical University , Kunming , China.
authors.forename: Yuansheng
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: e School of Public Health, Medical College of Soochow University , Suzhou , China.
authors.forename: Chen-Wei
authors.initials: CW
authors.lastname: Pan
mesh_terms: D000368:Aged; D044466:Asian People / Q000208:ethnology*; D002681:China / Q000453:epidemiology; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008913:Minority Groups / Q000706:statistics & numerical data*; D015995:Prevalence; D011625:Pterygium / Q000208:ethnology*; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data*
keywords: Epidemiology; ethnicity; pterygium; public health; risk factor