title: Prevalence of corneal astigmatism before cataract surgery in Chinese patients.
abstract: OBJECTIVE
  To assess the demographics and distribution of corneal astigmatism before cataract surgery in Chinese patients.
  
  
  METHODS
  State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
  
  
  METHODS
  Clinic-based cross-sectional study.
  
  
  METHODS
  From July 2009 to May 2011, preoperative bilateral partial coherence interferometry (IOLMaster) was performed in consecutive patients having cataract surgery. Patient demographics and keratometric data were recorded.
  
  
  RESULTS
  The mean age of the 2849 patients (4831 eyes) was 70.56 years ± 9.55 (SD); there was a predominance of women patients (64.0%). The mean axial length was 23.58 ± 1.13 mm. The mean corneal astigmatism in this cohort was 1.01 D (range 0.05 to 6.59 D). Corneal astigmatism was between 0.25 D and 1.25 D in 67.7% of eyes, 1.25 D or higher in 27.5% eyes, and less than 0.25 D in 4.8% of eyes. Astigmatism was with the rule in 25.1% of eyes, against the rule (ATR) in 58.2% of eyes, and oblique in 16.7% of eyes. The mean steep keratometry measurement was 44.76 ± 1.56 D. Against-the-rule astigmatism increased significantly with older age.
  
  
  CONCLUSIONS
  Corneal astigmatism largely fell between 0.25 D and 1.25 D in these predominantly elderly female Chinese patients, and ATR astigmatism increased with age.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Weirong
authors.initials: W
authors.lastname: Chen
authors.forename: Chengguo
authors.initials: C
authors.lastname: Zuo
authors.forename: Chuyin
authors.initials: C
authors.lastname: Chen
authors.forename: Jinai
authors.initials: J
authors.lastname: Su
authors.forename: Lixia
authors.initials: L
authors.lastname: Luo
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
authors.forename: Yizhi
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000453:epidemiology*; D058452:Axial Length, Eye / Q000473:pathology; D002387:Cataract Extraction; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D057234:Preoperative Period; D015995:Prevalence; D012029:Refraction, Ocular / Q000502:physiology; D017678:Sex Distribution; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology