Recovery from Amblyopia in Adulthood: A Meta-Analysis

Abstract

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.

Comments on: Partial Recovery of Amblyopia After Fellow Eye Ischemic Optic Neuropathy: Response

“…Since publishing this article, we have extended our examination of this phenomenon to all published cases to identify clinical factors that facilitate recovery from amblyopia. 1 As Dr. Örnek points out, there are several potential mechanisms at play as we have outlined in a recent review. 2 We are committed to elucidating these mechanisms which hold translational potential for visual recovery beyond amblyopia.…”

“…In our meta-analysis of 101 reported cases with AEVA improvement after FE vision loss (which included this ION data set), multiple regression analysis revealed that FEVA nadir was independently associated with greater grains AEVA. 1 We did not examine durability of AEVA because follow-up duration is highly variable across the few reports that include this information. Data from animal models demonstrate that the functional and structural consequences of amblyopia can be reversed at older ages with temporary FE inactivation with durability even after FE responses have returned to baseline.…”