A new counter-intuitive therapy for adult amblyopia

Visual cortex plasticity is high during a critical period of early postnatal development, but rapidly diminishes with the transition to adulthood. Accordingly, visual disorders such as amblyopia (lazy eye), can be treated early in life by long-term occlusion of the non-amblyopic eye, but may become irreversible in adults, because of the decline in brain plasticity. Here we show that a novel counter-intuitive approach can promote the recovery of visual function in adult amblyopic patients: short-term occlusion of the amblyopic (not the fellow) eye, combined with physical exercise (cycling). After six brief (2h) training sessions, visual acuity improved in all ten patients (0.15±0.02 LogMar), and six of them also recovered stereopsis. The improvement was preserved for up to one year after training. A control experiment revealed that physical activity was crucial for the recovery of visual acuity and stereopsis. Thus, we propose a non-invasive therapeutic strategy for adult human amblyopia based an inverse-occlusion and physical exercise procedure.