Comparison Between Dichoptic and Monocular Training Protocols for Treating Monocular Amblyopia: A Meta-Analysis and Systematic Review

To review the efficacy of dichoptic and monocular strategies for treating monocular amblyopia, and to examine the factors that determine the degree of recovery from amblyopia. Mean and individual participant data (IPD) from studies that used either monocular or dichoptic training methods to treat monocular amblyopic patients were analyzed. A mixed-effects model was used to analyze influential factors. Studies were searched using PubMed, OVID, Cochrane library, and EBM reviews. The mean improvements in visual acuity (VA) for dichoptic and monocular training were 0.153 logMAR and 0.162 logMAR, respectively. In the dichoptic training subgroup, the mean VA improvements were 0.201 logMAR, and 0.145 logMAR for strabismic and anisometropic amblyopia, respectively. In the monocular training subgroup, the mean VA improvements were 0.171 logMAR, and 0.143 logMAR for strabismic and anisometropic amblyopia, respectively. The mean improvements in stereopsis of dichoptic training and monocular training were 1.201 octaves and 1.661 octaves, respectively. Baseline visual acuity of the amblyopic eye and training duration were significant factors influencing visual gains. We found no significant impacts of age, astigmatism, and baseline stereopsis on visual acuity and stereopsis outcomes. This IPD meta-analysis provides evidence that both monocular and dichoptic training yield different visual acuity outcomes in treating unilateral amblyopia. Subgroup analysis suggests that strabismic amblyopia may respond differently to dichoptic training. Baseline visual acuity of the amblyopic eye and training duration are significant factors influencing visual gains. We believe that a more personalized training program could help restore binocularity in patients with monocular amblyopia.