title: Prevalence of and racial differences in pterygium: a multiethnic population study in Asians.
abstract: OBJECTIVE
  To describe the prevalence and risk factors of pterygium in a multiethnic Asian population and to examine racial differences.
  
  
  METHODS
  Population-based study in Singapore, located 1° north of the equator.
  
  
  METHODS
  Data were analyzed from 8906 participants from 3 population-based studies of Malays, Indians, and Chinese persons 40 years of age and older conducted between 2004 and 2011.
  
  
  METHODS
  Standardized slit-lamp examinations were performed by trained study ophthalmologists to examine the anterior segment for evidence of pterygium. Every subject underwent standardized systemic and ocular examinations, interviewer-administered questionnaires, and blood investigations for risk factor assessment. Regression and principle component analysis models were constructed to study the relationship of race and other factors to pterygium.
  
  
  METHODS
  Any pterygium and severe (grade 3 or opaque) pterygium.
  
  
  RESULTS
  The overall prevalence of any pterygium was 10.1% (n = 900), of which severe pterygium was seen in 1.6% (n = 142). The prevalence of any pterygium was more common in Malays (15.5%) than Chinese (7.0%; P<0.001) or Indians (7.0%; P<0.001). Multivariate analysis revealed increasing age (P<0.001), male gender (P<0.001), Malay race (P<0.001), and having a poorer education level (P<0.001) as significant factors for any pterygium. Race contributed significantly to presence of any pterygium (41%; P<0.001) or presence in both eyes (33%; P<0.001) compared with other risk factors. Severe pterygium was associated with outdoor occupation (P = 0.02), but race was not a significant risk factor in multivariate analysis.
  
  
  CONCLUSIONS
  This population-based study in Asian persons of different races living in the same geographical location at the equator indicated that race is a significant risk factor for pterygium, with Malays having higher prevalence than Indians and Chinese, while controlling for other risk factors.
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore. tien_yin_wong@nuhs.edu.sg
authors.forename: Marcus
authors.initials: M
authors.lastname: Ang
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.forename: Wanling
authors.initials: W
authors.lastname: Wong
authors.forename: Yingfeng
authors.initials: Y
authors.lastname: Zheng
authors.forename: Daniel
authors.initials: D
authors.lastname: Chua
authors.forename: Ainur
authors.initials: A
authors.lastname: Rahman
authors.forename: Seang-Mei
authors.initials: SM
authors.lastname: Saw
authors.forename: Donald T H
authors.initials: DT
authors.lastname: Tan
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000208:ethnology*; D001794:Blood Pressure; D005006:Ethnicity / Q000208:ethnology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009790:Occupations; D015995:Prevalence; D011625:Pterygium / Q000208:ethnology*; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology