A randomized trial of near versus distance activities while patching for amblyopia in children aged 3 to less than 7 years

Abstract

Purpose: To determine whether performing near activities while patching for amblyopia enhances improvement in visual acuity.

Design: Randomized clinical trial.

Participants: A total of 425 children, aged 3 to <7 years, with amblyopia (20/40-20/400) that was caused by anisometropia, strabismus, or both, and that persisted after treatment with spectacles.

Methods: Children were randomized to 2 hours of patching per day with near activities or 2 hours of patching per day with distance activities. Instruction sheets describing common near and distance activities were given to the parents. Study visits were scheduled at 2, 5, 8, and 17 weeks. In weeks without a visit, weekly telephone calls were made to the parent to monitor and encourage compliance during the first 8 weeks.

Main outcome measure: Masked assessment of visual acuity by isolated crowded HOTV optotypes at 8 weeks.

Results: At 8 weeks, improvement in amblyopic eye visual acuity averaged 2.6 lines in the distance activities group and 2.5 lines in the near activities group (mean difference in acuity between groups, adjusted for baseline acuity, 0.0 lines 95% confidence interval, -0.3 to 0.3). The 2 groups also appeared statistically similar at the 2-, 5-, and 17-week visits. At the 17-week examination, children with severe amblyopia improved a mean of 3.6 lines with 2 hours of daily patching.

Conclusions: Performing common near activities does not improve visual acuity outcome when treating anisometropic, strabismic, or combined amblyopia with 2 hours of daily patching. Children with severe amblyopia may respond to 2 hours of daily patching.

Figure 1. Visit Completion

Flow chart showing study completion in each treatment group.

Figure 2. Amblyopic Eye Visual Acuity in Each Group at Baseline, 2 Weeks, 5 Weeks, 8 Weeks, and 17 Weeks

Amblyopic eye visual acuity in each group at baseline, 2 weeks, 5 weeks, 8 weeks, and 17 weeks. Box-whisker plot demonstrating mean (dashed horizontal line), median (solid horizontal line), 25 – 75^th percentiles (extremes of the box), 10-90^th percentiles (whiskers), and 5-95^th percentiles (solid circles) of visual acuity at the visit. (logMAR = logarithm of minimum angle of resolution)

Figure 3. Cumulative Distribution of Amblyopic Eye Visual Acuity Scores at the 8-Week Outcome Examination According to Treatment Group

Cumulative distribution of amblyopic eye visual acuity scores at 8-week outcome exam according to treatment group and amblyopia severity group at baseline.

Figure 4. Amblyopic Eye Visual Acuity in Each Group at Baseline, 2 Weeks, 5 Weeks, 8 Weeks, and 17 Weeks By Severity

Amblyopic eye visual acuity in each treatment and amblyopia severity group at baseline, 2 weeks, 5 weeks, 8 weeks, and 17 weeks. Box-whisker plot demonstrating mean (dashed horizontal line), median (solid horizontal line), 25 – 75^th percentiles (extremes of the box), 10-90^th percentiles (whiskers), and 5-95^th percentiles (solid circles) of visual acuity at the visit. (logMAR = logarithm of minimum angle of resolution)

Figure 4. Amblyopic Eye Visual Acuity in Each Group at Baseline, 2 Weeks, 5 Weeks, 8 Weeks, and 17 Weeks By Severity

Amblyopic eye visual acuity in each treatment and amblyopia severity group at baseline, 2 weeks, 5 weeks, 8 weeks, and 17 weeks. Box-whisker plot demonstrating mean (dashed horizontal line), median (solid horizontal line), 25 – 75^th percentiles (extremes of the box), 10-90^th percentiles (whiskers), and 5-95^th percentiles (solid circles) of visual acuity at the visit. (logMAR = logarithm of minimum angle of resolution)