title: Prevalence and etiology of amblyopia in Southern India: results from screening of school children aged 5-15 years.
abstract: OBJECTIVE
  To determine the prevalence and etiology of amblyopia in school children.
  
  
  METHODS
  A total of 4020 school children aged between 5 and 15 years were screened in a population-based, cross-sectional study. Best corrected visual acuity and detailed ophthalmic evaluation were performed in all participants. Amblyopia associated with degraded visual input due to high refractive error was labeled ametropic amblyopia. Anisometropic amblyopia was diagnosed in participants with interocular refractive error difference ≥1 diopter. Strabismic amblyopia included that due to conflicting visual inputs between the eyes due to squint. Stimulus deprivation amblyopia was defined as amblyopia due to obstruction of the visual axis.
  
  
  RESULTS
  Prevalence of amblyopia was 1.1% (n = 44). The number of boys with amblyopia (n = 25, 57%) was slightly higher than the number of girls with amblyopia (n = 19, 43%; p = 0.6). A total of 28 (63.7%) children had mild to moderate amblyopia, whereas 16 (36.3%) had severe amblyopia. Underlying amblyogenic causes were ametropia (50%), anisometropia (40.9%), strabismus (6.8%), visual deprivation (4.5%) and combined causes (2.2%). No statistically significant difference was noted in the prevalence of amblyopia between rural (1.2%) and urban (0.9%) children (p = 0.5).
  
  
  CONCLUSIONS
  In this study, the prevalence of amblyopia was 1.1% of the school children. Ametropia and anisometropia were the most common causes of amblyopia. We did not find any significant difference in amblyopia prevalence between rural and urban school children.
authors.affiliation: Nayana Super Specialty Eye Hospital and Research Center, Davangere, Karnataka, India. drgsunil@yahoo.com
authors.forename: Sunil
authors.initials: S
authors.lastname: Ganekal
authors.forename: Vishal
authors.initials: V
authors.lastname: Jhanji
authors.forename: Yuanbo
authors.initials: Y
authors.lastname: Liang
authors.forename: Syril
authors.initials: S
authors.lastname: Dorairaj
mesh_terms: D000293:Adolescent; D000550:Amblyopia / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D015858:Anisometropia / Q000150:complications / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D012030:Refractive Errors / Q000150:complications / Q000453:epidemiology*; D012424:Rural Population / Q000706:statistics & numerical data; D017678:Sex Distribution; D014505:Urban Population / Q000706:statistics & numerical data; D015351:Vision Screening; D014792:Visual Acuity / Q000502:physiology