A Comparative Study Between Dissociative Treatment and Binocular Interactive Treatment in Amblyopia
Condition: Amblyopia
MeSH terms: Amblyopia
Study type: Interventional

Summary: 
      Amblyopia is a unilateral or, infrequently, a bilateral reduction of best corrected visual
      acuity which cannot be attributed to coexisting eye or visual pathway disease. Amblyopia can
      be due to eye-crossing occurring in early childhood or due to error of refraction whether a
      high difference between the two eyes or very high bilateral refractive errors.Another cause
      could be visual deprivation like the presence of congenital cataract.

      The prevalence of amblyopia worldwide is approximately 1%-5% .In Egypt, a study that was held
      in Upper Egypt, found that the prevalence of amblyopia was 1.49%, which is higher in rural
      areas than in urban areas.

      Several modalities of treatment for amblyopia are available, yet occlusion treatment is the
      gold standard involving covering the good eye with a patch for a prescribed period of time
      ranging from 10 minutes daily to all waking hours. However, its effectiveness decreases in
      older children and adults.

      Disadvantages include prolonged treatment leading to poor compliance, patching related
      distress, relationship strain and stigma. In extreme cases, non-compliance with patching
      results in a costly hospital admission to supervise the patching treatment. In addition,
      wearing a patch eliminates any advantage of binocularity. Not to mention that not all
      patients respond to patching and of those who do, many have residual amblyopia after
      treatment is stopped regardless of compliance. More importantly, binocular vision is not
      automatically restored once the vision in the amblyopic eye has been improved. In fact, once
      the patch is removed after therapy, the amblyopic eye could be suppressed by the better
      seeing eye and can lose some of the gains achieved as a result of therapy.

      Another modality of treatment is atropine eye drops and optical penalisation which are
      usually secondary treatments to failed patching but carrying the same disadvantages as the
      ordinary patching.

      Advances in amblyopia treatment include dichoptic training, perceptual learning, and video
      gaming. These depend on the fact that the adult brain has been shown to be much more plastic
      than it was once believed to be and hence have the advantage of expanding the age of response
      in adults.

      Perceptual learning approaches have the advantage of being a dichoptic (binocular treatment
      using both eyes) approach which is independent of age and type of amblyopia.

      A step further to conventional treatment is the use of a home-based approach allowing remote
      internet monitoring of treatment between office visits and hence better compliance. In
      addition a video game version of the treatment is developed to make it more enjoyable for
      improving compliance.

      Our goal is to compare the outcome between the gold standard occlusion therapy and one of the
      dichoptic treatments.
    

Detailed description: 
      Introduction Amblyopia is a unilateral or, infrequently, a bilateral reduction of best
      corrected visual acuity which cannot be attributed to coexisting eye or visual pathway
      disease. Amblyopic eyes may have decreased contrast sensitivity and accommodation deficit.
      The fellow eye is not often normal but has subtle deficits.This can be explained by
      interocular suppression, or inhibition of the amblyopic eye by the strong eye, with
      psychophysical and physiological evidence.

      Amblyopia can be classified as follows: 1) Strabismic occurring in early childhood 2)
      Refractive: a) Anisometropic b) High bilateral refractive errors 3) Visual deprivation.

      The prevalence of amblyopia worldwide is approximately 1%-5%. In Egypt, a study that was held
      in Upper Egypt, found that the prevalence of amblyopia was 1.49%, which is higher in rural
      areas than in urban areas.

      Several modalities of treatment for amblyopia are available, yet occlusion treatment is the
      gold standard involving covering the good eye with a patch for a prescribed period of time
      ranging from 10 minutes daily to all waking hours. However, its effectiveness decreases in
      older children and adults.

      Disadvantages include prolonged treatment leading to poor compliance, patching related
      distress, relationship strain and stigma. In extreme cases, non-compliance with patching
      results in a costly hospital admission to supervise the patching treatment. In addition,
      wearing a patch eliminates any advantage of binocularity. Not to mention that not all
      patients respond to patching and of those who do, many have residual amblyopia after
      treatment is stopped regardless of compliance. More importantly, binocular vision is not
      automatically restored once the vision in the amblyopic eye has been improved. In fact, once
      the patch is removed after therapy, the amblyopic eye could be suppressed by the better
      seeing eye and can lose some of the gains achieved as a result of therapy.

      Another modality of treatment is atropine eye drops and optical penalisation which are
      usually secondary treatments to failed patching but carrying the same disadvantages as the
      ordinary patching.

      Advances in amblyopia treatment include dichoptic training, perceptual learning, and video
      gaming. These depend on the fact that the adult brain has been shown to be much more plastic
      than it was once believed to be and hence have the advantage of expanding the age of response
      in adults.

      Perceptual learning approaches have the advantage of being a dichoptic (binocular treatment)
      approach which is independent of age and type of amblyopia. Furthermore, it has been shown
      recently that therapy promotes binocular vision by strengthening stereopsis and reducing
      suppression.

      A step further to conventional treatment is the use of a home-based approach allowing remote
      internet monitoring of treatment between office visits and hence better compliance. In
      addition a video game version of the treatment is developed to make it more enjoyable for
      improving compliance.

      Aim of the work:

      To compare the gold standard occlusion therapy alone with dichoptic therapy

      Patients and Methods:

      Design:

      The study will be a prospective experimental controlled study.

      Patients of the study:

      From the vicinity of the ophthalmology outpatient clinic of Ain Shams University Hospital,
      100 patients of both sexes with amblyopia will be enrolled to this study. Informed consents
      will be obtained from adult patients and children's parents.

      Patients will be assigned randomly into two groups:

      Group A: 50 patients will receive the gold standard occlusion therapy

      Group B: 50 patients will receive dichoptic treatment in the form of playing a video game
      (Lazy Eye Blocks ®) while wearing a red/green goggle.

      Each group will be subdivided according to age:

        1. From 4 to 7 years.

        2. From above 7 to 12 years.

        3. From above 12 to 30 years.

      Hours of occlusion will be classified according to the degree of amblyopia:

        -  Mild to moderate amblyopia (Best corrected visual acuity (BCVA)< 0.2): 2-4 hours
           occlusion

        -  Severe (BCVA> 0.2): 4-6 hours occlusion

      Hours of dichoptic treatment in group B will be classified according to the degree of
      amblyopia:

        -  Mild to moderate amblyopia (BCVA< 0.2): 2-4 hours of treatment

        -  Severe (BCVA> 0.2): 4-6 hours of treatment

      Methods

      All patients will undergo the following:

        1. Full medical and ophthalmic history

        2. Examination:

      A) External Appearance:

      Anomalous Head Position, globes (e.g., proptosis), lids (e.g. ptosis).

      B) Refraction:

      With and without cyclopegia

      C) Visual acuity:

      With and without correction using Snellen acuity chart and preferential looking test for
      non-verbal patients.

      D) Motility:

      Ductions and versions (9 positions of gaze) E) Angle of deviation if any

      F) Fixation :

      Fixation behavior (fixation preference) will be tested via base down 10 prism diopter
      fixation preference test.

      G) Quantitative Binocular vision assessment H) Anterior segment examination. I) Posterior
      segment examination using indirect ophthalmoscopy with a 20 diopter lens through a dilated
      pupil.

      All patients in Group A will receive the gold standard occlusion therapy. All patients in
      Group B will receive dichoptic treatment
    

Intervention name(s): eye patch; dichoptic treatment
Intervention type(s): Device; Device
Intervention description(s): Occluding the better seeing eye for a given number of hours daily; dichoptic treatment in the form of playing a video game (Lazy Eye Blocks ®) while wearing a red/green goggle.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Patients of the study will be recruited from the ophthalmology outpatient clinic of Ain Shams University Hospital.100 patients of both sexes with amblyopia will be enrolled. Informed consents will be obtained from adult patients and children's parents.
Patients will be assigned randomly:
Group A:50 patients will receive the gold standard occlusion therapy while playing a video game (Lazy Eye Tetris games such as Lazy Eye Blocks ®).Group B:50 patients will receive dichoptic treatment in the form of playing a video game (Lazy Eye Tetris games such as Lazy Eye Blocks ®) while wearing a red/green goggle.Each group will be subdivided according to age:
1)4 to 7 years. 2)>7 to 12 years. 3)>12 to 30 years.
Hours of occlusion /dichoptic treatment will be classified according to the degree of amblyopia:
Mild to moderate amblyopia (Best corrected visual acuity (BCVA)< 0.2) : 2-4 hours
Severe (BCVA> 0.2) : 4-6 hours
All patients will undergo full ophthalmological examination
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Amblyopia; Interactive Binocular Treatment; Dissociative Treatment; Occlusion; Patching