Spontaneous recovery from amblyopia following fellow eye vision loss: a systematic review and narrative synthesis.

Background: The effectiveness of traditional amblyopia therapies is largely restricted to childhood. However, spontaneous recovery in adulthood is possible following vision loss in the fellow eye due to enucleation, injury, or disease. The twofold purpose of this study was (1) to define the incidence of recovery and (2) to elucidate the clinical features associated with greater amblyopic eye gains.

Methods: A systematic review of three databases yielded 24 reports containing 110 cases of patients ≥18 years old with unilateral amblyopia and vision-limiting fellow eye pathology.

Results: Our analysis revealed that 25 of 42 of adult patients (59.5%) gained ≥2 logMAR lines in the amblyopic eye after fellow eye vision loss. The degree of improvement is clinically meaningful (median, 2.6 logMAR lines). Recovery occurs within 12 months of initial loss of fellow eye vision. Regression analysis demonstrated that younger age, worse baseline visual acuity in the amblyopic eye, and worse vision in the fellow eye independently conferred greater gains in amblyopic eye visual acuity. Recovery occurs across amblyopia types and fellow eye pathologies, although disease entities affecting fellow eye retinal ganglion cells demonstrate shorter latencies to recovery.

Conclusions: Amblyopia recovery after fellow eye injury demonstrates that the adult brain harbors the neuroplastic capacity for clinically meaningful recovery, which could potentially be harnessed by novel approaches to treat adults with amblyopia.