title: Does partial occlusion promote normal binocular function?
abstract: OBJECTIVE
  There is growing evidence that abnormal binocular interactions play a key role in the amblyopia syndrome and represent a viable target for treatment interventions. In this context the use of partial occlusion using optical devices such as Bangerter filters as an alternative to complete occlusion is of particular interest. The aims of this study were to understand why Bangerter filters do not result in improved binocular outcomes compared to complete occlusion, and to compare the effects of Bangerter filters, optical blur and neutral density (ND) filters on normal binocular function.
  
  
  METHODS
  The effects of four strengths of Bangerter filters (0.8, 0.6, 0.4, 0.2) on letter and vernier acuity, contrast sensitivity, stereoacuity, and interocular suppression were measured in 21 observers with normal vision. In a subset of 14 observers, the partial occlusion effects of Bangerter filters, ND filters and plus lenses on stereopsis and interocular suppression were compared.
  
  
  RESULTS
  Bangerter filters did not have graded effect on vision and induced significant disruption to binocular function. This disruption was greater than that of monocular defocus but weaker than that of ND filters. The effect of the Bangerter filters on stereopsis was more pronounced than their effect on monocular acuity, and the induced monocular acuity deficits did not predict the induced deficits in stereopsis.
  
  
  CONCLUSIONS
  Bangerter filters appear to be particularly disruptive to binocular function. Other interventions, such as optical defocus and those employing computer generated dichoptic stimulus presentation, may be more appropriate than partial occlusion for targeting binocular function during amblyopia treatment.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Jingrong
authors.initials: J
authors.lastname: Li
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thompson
authors.forename: Zhaofeng
authors.initials: Z
authors.lastname: Ding
authors.forename: Lily Y L
authors.initials: LY
authors.lastname: Chan
authors.forename: Xiang
authors.initials: X
authors.lastname: Chen
authors.forename: Minbin
authors.initials: M
authors.lastname: Yu
authors.forename: Daming
authors.initials: D
authors.lastname: Deng
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hess
mesh_terms: D000550:Amblyopia / Q000503:physiopathology / Q000628:therapy*; D015350:Contrast Sensitivity; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012016:Reference Values; D012683:Sensory Deprivation; D015348:Vision, Binocular / Q000502:physiology*; D055815:Young Adult