The goals of this study are:

• To determine whether the visual acuity improvement obtained with part-time (6 hours) patching is equivalent to the visual acuity improvement obtained with minimal patching (2 hours) for moderate amblyopia.
• To develop more precise estimates than currently available for the visual acuity improvement that occurs during treatment of amblyopia with patching.
• To identify factors that may be associated with successful treatment of amblyopia with patching.

Amblyopia is the most common cause of monocular visual impairment in both children and young and middle-aged adults. Patching has been the mainstay of amblyopia therapy. It is generally held that the response to treatment is best when it is instituted at an early age, particularly by age two or three, and is poor when attempted after eight years of age.

For moderate amblyopia, patching is the most commonly prescribed treatment although other modalities such as atropine penalization are also prescribed. There is no specific patching regimen that is widely accepted for treatment of moderate amblyopia and limited or no data available to favor the use of one specific regimen; both minimal occlusion (e.g., 2 hours per day) and six or more hours per day of patching are prescribed in clinical practice.

The study is a randomized trial comparing daily patching regimes for children with moderate amblyopia. It will consist of about 160 children. Patients in the moderate (20/40-20/80) group will patch part-time (6 hours) or minimal time (2 hours) of each day for the 4-month study period. There are at least two follow up visits during the 4-month period. Visual acuity is the major study outcome. It is assessed at the 4-month exam.

Inclusion Criteria:

• Patients must be less than 7 years of age with the original cause of amblyopia as strabismus or anisometropia.
• Visual Acuity in the amblyopic eye must be between 20/40 and 20/80.
• Visual acuity in the sound eye of 20/40 or better.
• There must be at least 3 lines of acuity difference between the two eyes.

Exclusion Criteria:

• Patching treatment (other than spectacles) within six months prior to enrollment and other amblyopia treatment of any type used within one month prior to enrollment.