Recovery from Amblyopia in Adulthood: A Meta-Analysis.

Purpose: The effectiveness of traditional amblyopia therapies is largely restricted to childhood. However, recovery in adulthood is possible following removal or vision-limiting disease of the fellow eye. Study of this phenomenon is currently limited to isolated case reports and a few case series, with reported incidence ranging from 19-77% . We set out to accomplish two distinct goals: (1) define the incidence of clinically meaningful recovery and (2) elucidate the clinical features associated with greater amblyopic eye gains.

Methods: A systematic review of 3 literature databases yielded 23 reports containing 109 cases of patients ≥18 years old with unilateral amblyopia and vision-limiting fellow eye pathology.

Results: Study 1 revealed 25/42 (59.5%) of adult patients gained ≥2 logMAR lines in the amblyopia eye after FE vision loss. The overall degree of improvement is clinically meaningful (median 2.6 logMAR lines). Study 2 showed that for cases with amblyopic eye visual acuity improvement, recovery occurs within 12 months of initial loss of fellow eye vision. Regression analysis revealed that younger age, worse baseline 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.