Objectives and Rationale:
This study is addressing issues related to the treatment of amblyopia in children 3 to <7 years old with visual acuity 20/40 to 20/400. The study consists of two phases: (1) a Spectacle Phase in which patients are prescribed spectacles and followed until maximal improvement in visual acuity has occurred and (2) a Randomized Trial comparing a group using patching treatment (in addition to spectacle correction) with a control group using spectacle correction only.
The sample size for the primary analysis for the randomized trial has been estimated to be 134 patients. Patients will be enrolled into the Spectacle Phase until the recruitment goal for the Randomized Trial is reached.
Summary of Results:
84 children 3 to less than 7 years old were enrolled with untreated anisometropic amblyopia ranging from 20/40 to 20/250. Amblyopia improved with optical correction by 2 or more 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 followed in the control group of the subsequent randomized trial, with amblyopia resolving in 6.
In a randomized multi-center clinical trial, 180 children 3 to 7 years old with best-corrected amblyopic eye visual acuity of 20/40 to 20/400 were assigned to receive either 2 hours of daily patching with one hour of near visual activities or spectacles alone. The 5-week outcome visit was completed by 173 (96%) of the 180 patients. There were no deaths. The patients not completing the study either withdrew of were lost to follow up. Improvement in visual acuity of the amblyopic eye from baseline to 5 weeks averaged 1.1 lines in the patching group and 0.5 lines in the control group (P=0.006), and improvement from baseline to best measured visual acuity at any visit averaged 2.2 lines in the patching group and 1.3 lines in the control group (P<0.001).
Refractive correction alone improves visual acuity 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.
Following a period of treatment with spectacles, two hours of daily patching combined with one hour of near visual activities modestly improves moderate to severe amblyopia in children 3 to 7 years old.