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Inna Tsirlin, Linda Colpa, Herb Goltz, Agnes Wong; Plasticity in adult amblyopia: a meta-review and analysis. Journal of Vision 2015;15(12):656. doi: 10.1167/15.12.656.
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Amblyopia is a neuro-developmental disorder involving a decrease in visual acuity that cannot be explained by ocular abnormalities. It affects 2-3% of the population and is the prevalent cause of monocular blindness. Patching of the amblyopic eye is a powerful treatment in early childhood but its effectiveness decreases with age, which has been attributed to decreased plasticity in the adult brain. In the last few decades new treatment methods including dichoptic training, perceptual learning and video games, were developed that improved visual acuity and/or stereoacuity in adult amblyopia. To understand the factors involved in adult plasticity in amblyopia, its clinical significance and to compare the treatments, we have used mean and individual participant data (IPD) meta-analyses on 19 studies with close to 200 individual scores. Our analysis showed that the average improvement in visual acuity (0.19 logMAR) was above mean test-retest reliability for acuity tests (0.14 logMAR) with 67% of subjects improving by more than this amount. Moreover, half of the subjects improved their stereo acuity by 2 octaves or more. The most important factor was the severity of amblyopia at the onset of treatment. Subjects with more severe amblyopia improved more on visual acuity and less on stereo sensitivity than those with the milder condition. Better binocularity was a predictor of improvements in stereo sensitivity. The different treatments, though employing very diverse strategies, yielded largely similar degrees of improvement on both measures. This suggests that any task involving sufficient engagement of the amblyopic eye could induce plasticity. We interpret this effect as the result of improvement in visual attention to the input from the amblyopic eye. Interocular suppression, which leads to amblyopia, could occur due to signal modulation by visual attention. Forcing visual attention to favor the amblyopic eye’s input might release those suppressive influences, thus improving visual function.
Meeting abstract presented at VSS 2015
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