title: Prevalence and associations of anisometropia with spherical ametropia, cylindrical power, age, and sex in refractive surgery candidates.
abstract: OBJECTIVE
  To analyze the prevalence and associations of anisometropia with spherical ametropia, astigmatism, age, and sex in a refractive surgery population.
  
  
  METHODS
  Medical records of 27,070 eyes of 13,535 refractive surgery candidates were reviewed. Anisometropia, defined as the absolute difference in mean spherical equivalent powers between right and left eyes, was analyzed for subjective (A(subj)) and cycloplegic refraction (A(cycl)). Correlations between anisometropia (>1 diopter) and spherical ametropia, cylindrical power, age, and sex, were analyzed using χ² and nonparametric Kruskal-Wallis or Mann-Whitney tests and binomial logistic regression analyses. Power vector analysis was applied for further analysis of cylindrical power.
  
  
  RESULTS
  Prevalence of A(subj) was 18.5% and of A(cycl) was 19.3%. In hyperopes, logistic regression analysis revealed that only spherical refractive error (odds ratio [OR], 0.72) and age (OR, 0.97) were independently associated with anisometropia. A(subj) decreased with increasing spherical ametropia and advancing age. Cylindrical power and sex did not significantly affect A(subj). In myopes all explanatory variables (spherical power OR, 0.93; cylindrical power OR, 0.75; age OR, 1.02; sex OR, 0.8) were independently associated with anisometropia. Cylindrical power was most strongly associated with anisometropia. Advancing age and increasing spherical/cylindrical power correlated positively with increasing anisometropia in myopic subjects. Female sex was more closely associated with anisometropia.
  
  
  CONCLUSIONS
  This large-scale retrospective analysis confirmed an independent association between anisometropia and both spherical ametropia and age in refractive surgery candidates. Notably, an inverse relationship between these parameters in hyperopes was observed. Cylindrical power and female sex were independently associated with anisometropia in myopes.
authors: Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. slinke@uke.uni-hamburg.de
authors: Stephan J
authors: SJ
authors: Linke
authors: Gisbert
authors: G
authors: Richard
authors: Toam
authors: T
authors: Katz
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D015858:Anisometropia / Q000453:epidemiology* / Q000503:physiopathology; D001251:Astigmatism / Q000453:epidemiology* / Q000503:physiopathology; D019781:Corneal Topography; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012030:Refractive Errors / Q000453:epidemiology* / Q000503:physiopathology; D054140:Refractive Surgical Procedures; D012189:Retrospective Studies; D017678:Sex Distribution; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology