Morning Versus Evening Patching in Childhood Amblyopia

Overview

To determine whether the time of day at which daily occlusion (patching) is administered - morning (08:00-10:00) versus evening (17:00-19:00) - affects the amount of visual-acuity improvement in the amblyopic eye in children with unilateral amblyopia. Rationale: While occlusion therapy remains the mainstay for treatment of childhood amblyopia, existing trials have focused on patching duration, not on the timing of occlusion. Diurnal or chronobiological factors - such as fluctuations in neuroplasticity, attention, compliance, or visual demand during the day - may influence the efficacy of patching. Understanding whether timing matters could help optimize occlusion therapy, improve outcomes, and reduce treatment burden.

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: Daily occlusion of the non-amblyopic eye for 2 continuous hours, at assigned time window (Morning: 08:00-10:00; Evening: 17:00-19:00). During patching, child engages in near-vision tasks (reading, puzzles, coloring) for 20-30 min or more. Adherence monitored via parent diary/photos. Spectacle correction (if prescribed) maintained throughout. 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 improvement, adherence rate (% of days/patching sessions completed). 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 / Power (Summary): Target total enrollment \~100 children (≈ 50 per arm), to provide sufficient power to detect a clinically meaningful difference (≈ 1 line difference in BCVA) between morning and evening patching, while allowing for variability, drop-outs, and stratified analyses. 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.