title: Relationship between astigmatism and aging in middle-aged and elderly Japanese.
abstract: OBJECTIVE
  To study the effect of aging on astigmatism in adult Japanese.
  
  
  METHODS
  Measurements of refractive errors and keratometry were performed on 2161 randomly selected subjects (aged 40-79 years). The relation between age and the net value in diopters (D) of astigmatism was evaluated with a trend test. The relation between age and the polar value was also examined by linear regression analysis.
  
  
  RESULTS
  The mean (+/-SD) value of total and corneal astigmatism was -0.97 +/- 0.72 D and -0.86 +/- 0.63 D, respectively, and the net value of both increased with age (P trend < 0.001). The prevalence of either type of astigmatism also increased with age, according to the Cochran-Mantel-Haenzel test (P < 0.0001 for total and P < 0.01 for corneal astigmatism). The prevalence of against-the-rule astigmatism increased with age for either type of astigmatism (P < 0.0001 for total, P < 0.0001 for corneal). According to the analysis of polar values by age, the regression coefficient (+/-SE) for total and corneal astigmatism was -0.024 +/- 0.002 (P < 0.0001) and -0.028 +/- 0.002 (P < 0.0001), respectively. There was no statistical difference between these two regression coefficients.
  
  
  CONCLUSIONS
  The prevalence of astigmatism increases and the axis turns to against-the-rule with age. The result of the linear regression analysis indicates that the age-related change in astigmatism is mainly associated with changes in the cornea.
authors.affiliation: Department of Ophthalmology, Chubu National Hospital, Obu, Japan. kasano@nils.go.jp
authors.forename: Kazuko
authors.initials: K
authors.lastname: Asano
authors.forename: Hideki
authors.initials: H
authors.lastname: Nomura
authors.forename: Makiko
authors.initials: M
authors.lastname: Iwano
authors.forename: Fujiko
authors.initials: F
authors.lastname: Ando
authors.forename: Naoakira
authors.initials: N
authors.lastname: Niino
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimokata
authors.forename: Yozo
authors.initials: Y
authors.lastname: Miyake
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D044466:Asian People / Q000208:ethnology; D001251:Astigmatism / Q000208:ethnology / Q000503:physiopathology*; D003315:Cornea / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence