title: The effect of Bangerter filters on binocular function in observers with amblyopia.
abstract: OBJECTIVE
  We assessed whether partial occlusion of the nonamblyopic eye with Bangerter filters can immediately reduce suppression and promote binocular summation of contrast in observers with amblyopia.
  
  
  METHODS
  In Experiment 1, suppression was measured for 22 observers (mean age, 20 years; range, 14-32 years; 10 females) with strabismic or anisometropic amblyopia and 10 controls using our previously established "balance point" protocol. Measurements were made at baseline and with 0.6-, 0.4-, and 0.2-strength Bangerter filters placed over the nonamblyopic/dominant eye. In Experiment 2, psychophysical measurements of contrast sensitivity were made under binocular and monocular viewing conditions for 25 observers with anisometropic amblyopia (mean age, 17 years; range, 11-28 years; 14 females) and 22 controls (mean age, 24 years; range, 22-27; 12 female). Measurements were made at baseline, and with 0.4- and 0.2-strength Bangerter filters placed over the nonamblyopic/dominant eye. Binocular summation ratios (BSRs) were calculated at baseline and with Bangerter filters in place.
  
  
  RESULTS
  Experiment 1: Bangerter filters reduced suppression in observers with amblyopia and induced suppression in controls (P = 0.025). The 0.2-strength filter eliminated suppression in observers with amblyopia and this was not a visual acuity effect. Experiment 2: Bangerter filters were able to induce normal levels of binocular contrast summation in the group of observers with anisometropic amblyopia for a stimulus with a spatial frequency of 3 cycles per degree (cpd, P = 0.006). The filters reduced binocular summation in controls.
  
  
  CONCLUSIONS
  Bangerter filters can immediately reduce suppression and promote binocular summation for mid/low spatial frequencies in observers with amblyopia.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Zidong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Jinrong
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada Department of Optometry and Vision Science, Faculty of Science, The University of Auckland, Auckland, New Zealand.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thompson
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Daming
authors.initials: D
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Junpeng
authors.initials: J
authors.lastname: Yuan
authors.affiliation: School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China.
authors.forename: Lily
authors.initials: L
authors.lastname: Chan
authors.affiliation: Department of Ophthalmology, McGill University, Montreal, Canada.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hess
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Minbin
authors.initials: M
authors.lastname: Yu
mesh_terms: D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000503:physiopathology / Q000628:therapy*; D002648:Child; D004867:Equipment Design; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D011601:Psychophysics / Q000379:methods*; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity; D055815:Young Adult
keywords: amblyopia; binocular vision; contrast sensitivity; psychophysics