title: Prevalence of non-strabismic anomalies of binocular vision in Tamil Nadu: report 2 of BAND study.
abstract: BACKGROUND
  Population-based studies on the prevalence of non-strabismic anomalies of binocular vision in ethnic Indians are more than two decades old. Based on indigenous normative data, the BAND (Binocular Vision Anomalies and Normative Data) study aims to report the prevalence of non-strabismic anomalies of binocular vision among school children in rural and urban Tamil Nadu.
  
  
  METHODS
  This population-based, cross-sectional study was designed to estimate the prevalence of non-strabismic anomalies of binocular vision in the rural and urban population of Tamil Nadu. In four schools, two each in rural and urban arms, 920 children in the age range of seven to 17 years were included in the study. Comprehensive binocular vision assessment was done for all children including evaluation of vergence and accommodative systems. In the first phase of the study, normative data of parameters of binocular vision were assessed followed by prevalence estimates of non-strabismic anomalies of binocular vision.
  
  
  RESULTS
  The mean and standard deviation of the age of the sample were 12.7 ± 2.7 years. The prevalence of non-strabismic anomalies of binocular vision in the urban and rural arms was found to be 31.5 and 29.6 per cent, respectively. Convergence insufficiency was the most prevalent (16.5 and 17.6 per cent in the urban and rural arms, respectively) among all the types of non-strabismic anomalies of binocular vision. There was no gender predilection and no statistically significant differences were observed between the rural and urban arms in the prevalence of non-strabismic anomalies of binocular vision (Z-test, p > 0.05). The prevalence of non-strabismic anomalies of binocular vision was found to be higher in the 13 to 17 years age group (36.2 per cent) compared to seven to 12 years (25.1 per cent) (Z-test, p < 0.05).
  
  
  CONCLUSIONS
  Non-strabismic binocular vision anomalies are highly prevalent among school children and the prevalence increases with age. With increasing near visual demands in the higher grades, these anomalies could significantly impact the reading efficiency of children. Thus, it is recommended that screening for anomalies of binocular vision should be integrated into the conventional vision screening protocol.
authors.affiliation: Srimathi Sundari Subramanian Department of Visual Psychophysics, Elite School of Optometry (in collaboration with Birla Institute of Technology & Science, Pilani), Unit of Medical Research Foundation, Thomas Mount, Chennai, India.|Sankara Nethraralya - ORBIS Pediatric Ophthalmology Learning and Training Center, Sankara Nethralaya, Nungambakkam, Chennai, India.
authors.forename: Jameel Rizwana
authors.initials: JR
authors.lastname: Hussaindeen
authors.affiliation: Srimathi Sundari Subramanian Department of Visual Psychophysics, Elite School of Optometry (in collaboration with Birla Institute of Technology & Science, Pilani), Unit of Medical Research Foundation, Thomas Mount, Chennai, India.|Sankara Nethraralya - ORBIS Pediatric Ophthalmology Learning and Training Center, Sankara Nethralaya, Nungambakkam, Chennai, India.
authors.forename: Archayeeta
authors.initials: A
authors.lastname: Rakshit
authors.affiliation: Srimathi Sundari Subramanian Department of Visual Psychophysics, Elite School of Optometry (in collaboration with Birla Institute of Technology & Science, Pilani), Unit of Medical Research Foundation, Thomas Mount, Chennai, India.|Sankara Nethraralya - ORBIS Pediatric Ophthalmology Learning and Training Center, Sankara Nethralaya, Nungambakkam, Chennai, India.
authors.forename: Neeraj Kumar
authors.initials: NK
authors.lastname: Singh
authors.affiliation: Glaucoma Services, Sankara Nethralaya, Nungambakkam, Chennai, India.
authors.forename: Ronnie
authors.initials: R
authors.lastname: George
authors.affiliation: Sankara Nethraralya - ORBIS Pediatric Ophthalmology Learning and Training Center, Sankara Nethralaya, Nungambakkam, Chennai, India.
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Swaminathan
authors.affiliation: Birla Institute of Technology & Science, Pilani, Hyderabad, India.
authors.forename: Suman
authors.initials: S
authors.lastname: Kapur
authors.affiliation: Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania, USA.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Scheiman
authors.affiliation: Srimathi Sundari Subramanian Department of Visual Psychophysics, Elite School of Optometry (in collaboration with Birla Institute of Technology & Science, Pilani), Unit of Medical Research Foundation, Thomas Mount, Chennai, India.
authors.forename: Krishna Kumar
authors.initials: KK
authors.lastname: Ramani
mesh_terms: D000065:Accommodation, Ocular; D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D015835:Ocular Motility Disorders / Q000453:epidemiology*; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data; D013285:Strabismus / Q000453:epidemiology; D014505:Urban Population / Q000706:statistics & numerical data; D014786:Vision Disorders / Q000453:epidemiology*; D015348:Vision, Binocular; D014792:Visual Acuity
keywords: accommodation; accommodative infacility; binocular vision; convergence; convergence insufficiency; non-strabismic binocular vision anomalies; normative data; school screening