A randomized trial comparing Bangerter filters and patching for the treatment of moderate amblyopia in children

Abstract

Objective: To determine whether visual acuity improvement with Bangerter filters is similar to improvement with patching as initial therapy for children with moderate amblyopia.

Design: Randomized, clinical trial.

Participants: We enrolled 186 children, 3 to <10 years old, with moderate amblyopia (20/40-20/80).

Methods: Children were randomly assigned to receive either daily patching or to use a Bangerter filter on the spectacle lens in front of the fellow eye. Study visits were scheduled at 6, 12, 18, and 24 weeks.

Main outcome measures: Visual acuity in amblyopic eyes at 24 weeks.

Results: At 24 weeks, amblyopic eye improvement averaged 1.9 lines in the Bangerter group and 2.3 lines in the patching group (difference in mean visual acuities between groups adjusted for baseline acuity = 0.38 line). The upper limit of a 1-sided 95% confidence interval was 0.76 line, which slightly exceeded a prespecified noninferiority limit of <0.75 line. Similar percentages of subjects in each group improved > or =3 lines (Bangerter group 38% vs patching group 35%; P = 0.61) or had > or =20/25 amblyopic eye acuity (36% vs 31%, respectively; P = 0.86). There was a lower treatment burden in the Bangerter group as measured with the Amblyopia Treatment Index. With Bangerter filters, neither a fixation switch to the amblyopic eye nor induced blurring in the fellow eye to worse than that of the amblyopic eye was required for visual acuity improvement.

Conclusions: Because the average difference in visual acuity improvement between Bangerter filters and patching was less than half a line, and there was lower burden of treatment on the child and family, Bangerter filter treatment is a reasonable option to consider for initial treatment of moderate amblyopia.

Figure 1. Visit Completion by Treatment Group

Flow chart showing study completion in each treatment group.

Figure 2. Cumulative Distribution of Visual Acuity at 24-week Masked Exam

Cumulative distribution of amblyopic eye visual acuity scores at 24-week outcome exam according to treatment group.

Figure 3. Mean Visual Acuity in Amblyopic Eyes from Baseline to 24 Weeks

At each time point, the box on the left is the distribution of amblyopic eye visual acuity scores for the Bangerter group and the one on the right represents the patching group. The top and bottom of each box represents the 25^th and 75^th percentiles of the data and the line in the box is the median. The treatment group means are represented by a dot (Bangerter) or a square (patching) and are connected across the visits with lines. The bars extending above and below each box represent 1.5 times the interquartile range (difference between the 25^th and 75^th percentiles), and the open circles are outlier values.