Scoping Review of the Role of Accommodation and Binocular Coordination in Myopia Onset and Progression.

Background: The predominant theory, underlying most optical myopia control interventions, is that relative peripheral hyperopic defocus (RPHD) is a cause of myopia progression. However, interventions that reduce RPHD only slow myopia progression on average by ~50%, so other factors are likely to be involved. Objective: To explore the literature on accommodation and binocular coordination as possible factors in myopia development and progression. Methods: PubMed was searched for relevant keywords in September 2025. Non-human and non-English reports were excluded. Results: (1) Concerning myopia onset, the CLEERE study found changes in the interaction between accommodation and convergence (increasing AC/A ratio) from four years before myopia onset. This is thought to indicate compromised accommodation, supported by reduced positive relative accommodation before myopia onset in other longitudinal studies. (2) Regarding myopia progression, the magnitude of accommodative lag is not strongly correlated with rate of myopia progression. The validity of clinical measurements of accommodative lag has been questioned. Tests of eye alignment during near vision show a more convergent posture (esophoria) in some myopes around the time of myopia onset, probably secondary to increased AC/A ratio. If compromised accommodation and/or near esophoria are relevant to myopia progression, prescribing a near addition should be helpful. However, myopia control trials of bifocal and progressive addition lens spectacles show poor efficacy. Despite early indications of greater efficacy in cases with higher accommodative lag and/or near esophoria, poor treatment effects in this sub-group were subsequently found. Nonetheless, some individual cases with symptomatic convergence excess esophoria are likely to benefit from bifocal spectacles for symptomatic relief. Conclusion: Although accommodative dysfunction seems likely to play some role in myopia onset, accommodative and binocular factors are unlikely to be major causal factors in myopia progression. An additive risk factor risk-resilience model is presented and suggestions are made for further research.