Full-time Bangerter Filters Versus Part-time Daily Patching for Moderate Amblyopia in Children
Condition: Amblyopia
MeSH terms: Amblyopia
Study type: Interventional
Phase: Phase 3

Summary: 
      This study is a randomized clinical trial designed to evaluate the non-inferiority of
      Bangerter filters compared to 2 hours of daily patching as a primary treatment for moderate
      amblyopia (20/40 to 20/80) in children ages 3 to < 10 years.

      Secondary objectives of this study are (1) to determine the time course of visual improvement
      with Bangerter filter treatment, (2) to compare patient quality of life, measured by a
      modified Amblyopia Treatment Index, between patients treated with patching vs. Bangerter
      filters, (3) to determine whether blurring the sound eye to a visual acuity worse than the
      amblyopic eye predicts improvement in acuity, and (4) to determine whether a change in
      fixation to the amblyopic eye is predictive of improvement in visual acuity.

      The primary outcome assessment is visual acuity at 24 weeks for both the amblyopic and sound
      eyes.

      The primary analytic approach for the amblyopic eye acuity will involve construction of a
      one-sided 95% confidence interval to assess non-inferiority based on a treatment group
      comparison of logMAR visual acuity scores adjusted for baseline visual acuity scores in an
      analysis of covariance (ANCOVA) model.

      Sound eye acuity data will be reported for each treatment regimen at the 24-week visit as
      mean change (logMAR lines) from baseline and as the distribution of the number of lines of
      change from baseline.
    

Detailed description: 
      Amblyopia is the most common cause of monocular visual impairment in children, estimated to
      affect as many as 3.6% of the childhood population. The natural history of amblyopia is
      relatively unknown although it has been reported that visual acuity may deteriorate further
      without treatment.

      Although occlusion or patching of the sound eye has been the mainstay for amblyopia therapy,
      alternative treatment such as pharmacological or optical penalization may be as effective. In
      a randomized, controlled clinical trial of 419 children, 3 years to less than 7 years old
      with moderate amblyopia, patching was compared to atropine. Although improvement with
      atropine was initially slower, both treatments produced similar improvement after 6 months.

      Although both patching and atropine have been proven effective for treating amblyopia,
      neither treatment is without adverse side effects. Patching is associated with compliance
      difficulties, the need for continuous monitoring, and social stigma. Negative side effects
      observed in children treated with atropine include light sensitivity, facial flushing, and
      fever. In a randomized clinical trial comparing patching to atropine as a treatment for
      amblyopia, a questionnaire to assess the impact of patching and atropine treatment on the
      child and family indicated that both treatments were well tolerated overall, however,
      patching had lower compliance and higher social stigma than atropine.

      Bangerter filters, also known as Bangerter foils, have been used mainly as secondary
      amblyopia therapy following patching or atropine to either further improve or maintain the
      visual gain. One advantage of Bangerter filters compared to patching is that the lower
      density filters are not readily apparent and therefore would be expected to increase patient
      compliance due to reduced social stigma. Another advantage of Bangerter filters is that there
      is no opportunity for skin irritation from bandage adhesive, a commonly-reported side effect
      of patching. In addition, there is a theoretical advantage that Bangerter filters are less
      disruptive to binocular function during treatment compared to other modalities such as
      patching.

      Few data are available comparing Bangerter filters with patching for the treatment of
      amblyopia. Bonsall randomized 14 patients, 3 to 10 years old, with previously untreated
      strabismic/anisometropic amblyopia to either 6 hours of daily patching or full-time Bangerter
      filters. Baseline amblyopic eye acuity was 20/30 to 20/400 for the patching group and 20/30
      to 20/200 for the Bangerter group. The Bangerter filter prescribed was the minimum density
      foil needed to elicit a switch in fixation from the sound eye to the amblyopic eye. Visual
      acuity was measured every 6-8 weeks until the amblyopic eye visual acuity was equal to that
      of the sound eye, an improvement that was achieved in 5 of the 14 at the time the study was
      stopped. The average time to achieve equal vision between the amblyopic and sound eyes was
      about 4.5 months (142 days) for the foil group versus about 9 months (272 days) for the
      patching group. Both forms of therapy were equally tolerated. Despite good preliminary data,
      a large randomized clinical trial comparing the effectiveness of Bangerter filters to
      patching for the treatment of amblyopia has yet to be conducted.
    

Intervention name(s): Bangerter filters; Patching; Near activities
Intervention type(s): Device; Device; Procedure
Intervention description(s): Bangerter filter worn on sound eye spectacle lens full time; 2 hours daily patching of the sound eye; one hour near visual activities
Other intervention name(s): Coverlet, 3M Opticlude, Ortopad®
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Amblyopia; Patching; Bangerter filters