Objective: To compare weekend atropine sulfate use augmented by a plano lens for the sound eye with weekend atropine use alone for moderate amblyopia in children aged 3 years to younger than 7 years.

Methods: In a multicenter clinical trial, 180 children with moderate amblyopia (visual acuities of 20/40-20/100) were randomized to weekend atropine use augmented by a plano lens or weekend atropine use alone.

Main outcome measure: Masked assessment of amblyopic eye visual acuity using the Amblyopia Treatment Study HOTV testing protocol at 18 weeks.

Results: At 18 weeks, amblyopic eye improvement averaged 2.8 lines in the group that received atropine plus a plano lens and 2.4 lines in the group that received atropine alone (mean difference between groups adjusted for baseline acuity, 0.3 line; 95% confidence interval, -0.2 to 0.8 line). Amblyopic eye visual acuity was 20/25 or better in 24 patients (29%) in the group that received atropine only and 35 patients (40%) in the group that received atropine plus a plano lens (P = .03). More patients in the group that received atropine plus a plano lens had reduced sound eye visual acuity at 18 weeks; however, there were no cases of persistent reverse amblyopia.

Conclusions: As an initial treatment for moderate amblyopia, the augmentation of weekend atropine use with a plano lens does not substantially improve amblyopic eye visual acuity when compared with weekend atropine use alone. Application to Clinical Practice Treatment of children with unilateral amblyopia.