Binocular versus standard therapy for amblyopia - effect on visual acuity, adherence, and patient or caregiver reported outcomes: protocol for a systematic review.

backgroundTraditionally, monocular interventions, like patching, have been the gold standard in amblyopia treatment. However, the current understanding that amblyopia is a binocular rather than monocular condition has inspired a surge in binocular treatments, which encourage the simultaneous use of both eyes.

objectivesThis systematic review aims to evaluate the effects of binocular treatment for amblyopia among children (9 years and younger) versus standard monocular interventions (patching or atropine eye drops) in terms of best corrected visual acuity (BCVA), treatment adherence, and patient/caregiver-reported outcomes. Secondary outcomes include change in other visual outcomes (stereoacuity and contrast sensitivity), reported barriers to treatment, reported side effects, and sustained improvement in BCVA on follow up.

methodsA comprehensive search will be conducted on three databases (PubMed, Embase, and CENTRAL) and two trial registries (ClinicalTrials.gov and WHO ICTRP). A previous search will be updated to include results since inception through March 2026. Two blinded, independent reviewers will screen titles and abstracts against predetermined criteria. Eligible studies will undergo full-text screening by two blinded, independent reviewers. Randomized controlled trials that compare binocular and monocular interventions for amblyopia among children younger than 9 years of age will be included. The quality of included studies will be evaluated using the Cochrane risk of bias tool for randomized trials (RoB-2). Data analysis will be carried out using Revman software. Continuous variables will be summarized using mean difference (MD) and 95% confidence intervals [CI]. Meta-analyses will be performed employing random-effects models. DISCUSSION: Although similar reviews exist, binocular therapy is a fairly novel and nuanced treatment. As such, new research continues to add to the growing body of evidence. Furthermore, existing reviews mainly focus on post-interventional visual outcomes, while this review will also shine light on outcomes like adherence, patient or caregiver reported outcomes, reported barriers and side effects, and sustained improvement after treatment cessation. These outcomes will be important to all stakeholders involved: patients, caregivers, healthcare providers, and policy makers, especially with such a pervasive condition that can affect multiple aspects of a child's life, in addition to their family's lives, with possible consequences carried into adulthood. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42024502274.