A randomized trial of adding a plano lens to atropine for amblyopia

Background: Some children have residual amblyopia after treatment with atropine eyedrops for amblyopia due to strabismus and/or anisometropia. We conducted a randomized clinical trial to evaluate the effectiveness of augmenting the effect of atropine by changing the lens over the fellow eye to plano in children with residual amblyopia.

Methods: A total of 73 children 3 to <8 years of age (mean, 5.8 years) with stable residual amblyopia (range, 20/32 to 20/160, mean 20/63(+1)) were enrolled after at least 12 weeks of atropine treatment of the fellow eye. Participants were randomly assigned to continuing weekend atropine alone or wearing a plano lens over the fellow eye (while continuing atropine). The primary outcome was assessed at 10 weeks, and participants were followed until improvement ceased.

Results: At the 10-week primary outcome visit, amblyopic-eye visual acuity had improved an average of 1.1 lines with the plano lens and 0.6 lines with atropine only (difference adjusted for baseline visual acuity = + 0.5 line; 95% CI, -0.1 to +1.2). At the primary outcome or later visit when the best-measured visual acuity was observed, the mean amblyopic-eye improvement from baseline was 1.9 lines with the plano lens and 0.8 lines with atropine only.

Conclusions: When amblyopic-eye visual acuity stops improving with atropine treatment, there may be a small benefit to augmenting atropine therapy with a plano lens over the fellow eye. However, the effect was not statistically significant, and the large confidence interval raises the possibility of no benefit or a benefit larger than we observed. A larger study would be necessary to get a more precise estimate of the treatment effect.