Morning Versus Evening Patching in Childhood Amblyopia

Study Type: Prospective, randomized, parallel-group clinical trial.

Participants: Children aged 4-8 years with unilateral amblyopia; amblyopic-eye BCVA between 0.17-0.67 decimal (≈ 6/36-6/9); fellow-eye BCVA ≥ 0.80 decimal; refractive-dominant or strabismic/mixed amblyopia. Parental/guardian consent required.

Randomization & Stratification: Participants randomized 1:1 to "Morning patching" vs "Evening patching" arms. Stratified by age (4-<6 vs >=6-8), baseline visual acuity or amblyopia severity (moderate 6/36-<6/12 vs mild 6/12-6/9), and amblyopia type (refractive-dominant vs strabismic/mixed) - to ensure balance across key prognostic variables.

Intervention: Participants received daily occlusion of the fellow eye for 2 hours within the assigned treatment window: 07:00-10:00 for the morning group and 17:00-20:00 for the evening group. Near-vision activities, such as reading, puzzles, or coloring, were encouraged during patching but were not formally quantified. Caregivers recorded the start time, end time, and duration of each patching session in a daily diary. Missed weekday patching could be made up on weekends according to the study protocol. Spectacle correction, when prescribed, was maintained throughout the study.

Follow-up / Assessments:

Baseline exam (BCVA both eyes, refraction, ocular alignment/strabismus assessment, anterior and posterior segment exam, stereoacuity, instructions on patching/adherence, randomization).

Midpoint follow-up at 3 months (BCVA, adherence, adverse events. Telehealth acceptable if in-person not possible.).

Final follow-up at 6 months (BCVA (primary endpoint), stereoacuity, ocular alignment/strabismus assessment, anterior segment exam, adherence data review, adverse events, patching compliance summary.).

Primary Outcome: Change in best-corrected visual acuity (BCVA) of the amblyopic eye from baseline to month 6.

Secondary Outcomes: Stereoacuity, caregiver-reported patching adherence within the assigned treatment window, and the proportion of participants achieving at least a 0.20 logMAR improvement from baseline to Month 6.

Statistical Approach: Analysis of covariance (ANCOVA) comparing mean change in BCVA between arms, adjusting for baseline VA and stratification factors. Subgroup analyses by amblyopia type, baseline severity, age group.

Sample Size and Power: Assuming a clinically meaningful between-group difference of 0.12 logMAR, a common standard deviation of 0.18 logMAR, a two-sided alpha of 0.05, and 80% power, 37 evaluable participants per group were required. The target enrollment was increased to 42 participants per group, for a total of 84, to allow for attrition or unavailable Month-6 outcomes.

Duration & Timeline:

Each participant will be followed for 6 months of daily patching. The total study duration (from first enrollment to last follow-up) will depend on recruitment rate; estimated duration ~ 7-9 months including recruitment, follow-up, data cleaning, and analysis.

Significance & Expected Impact:

If timing of occlusion influences visual outcome, this could refine occlusion therapy recommendations - potentially improving efficacy, adherence, and convenience for patients and families. The trial may identify a more effective or practical patching schedule, thereby contributing to evidence-based amblyopia management.

Inclusion criteria

• Age: 4-8 years.
• Unilateral amblyopia.
• Amblyopic-eye BCVA decimal 0.17-0.67 (≈ 6/36-6/9).
• Fellow-eye BCVA ≥ 0.80 decimal (≈ 6/7.5 or better).
• Amblyopia type: refractive-dominant or strabismic/mixed.
• Parent/guardian consent obtained.

Exclusion criteria

• Bilateral amblyopia.
• Sensory-deprivation amblyopia (e.g., due to congenital cataract, ptosis, corneal opacity).
• Ocular surgery within the past 6 months, or planned surgery during study.
• Likely poor adherence (e.g., due to social, logistic, or family constraints).