Objective: To evaluate the effectiveness of refractive correction alone for the treatment of untreated anisometropic amblyopia in children 3 to <7 years old.

Design: Prospective, multicenter, noncomparative intervention.

Participants: Eighty-four children 3 to <7 years old with untreated anisometropic amblyopia ranging from 20/40 to 20/250.

Methods: Optimal refractive correction was provided, and visual acuity (VA) was measured with the new spectacle correction at baseline and at 5-week intervals until VA stabilized or amblyopia resolved.

Main outcome measures: Maximum improvement in best-corrected VA in the amblyopic eye and proportion of children whose amblyopia resolved (interocular difference of < or =1 line) with refractive correction alone.

Results: Amblyopia improved with optical correction by > or =2 lines in 77% of the patients and resolved in 27%. Improvement took up to 30 weeks for stabilization criteria to be met. After stabilization, additional improvement occurred with spectacles alone in 21 of 34 patients observed in a control group of a subsequent randomized trial, with amblyopia resolving in 6. Treatment outcome was not related to age, but was related to better baseline VA and lesser amounts of anisometropia.

Conclusion: Refractive correction alone improves VA in many cases and results in resolution of amblyopia in at least one third of 3- to <7-year-old children with untreated anisometropic amblyopia. Although most cases of resolution occur with moderate (20/40-20/100) amblyopia, the average 3-line improvement in VA resulting from treatment with spectacles may lessen the burden of subsequent amblyopia therapy for those with denser levels of amblyopia.