Abstract
Purpose :
Visual cortex plasticity is maximal during development, however some plasticity is retained also in adults. This short-term homeostatic plasticity is present also in amblyopic patients (Xhou et al 2013, Lunghi et al 2016) and is boosted by moderate levels of physical activity (Lunghi & Sale, 2015). Short-term inverse occlusion combined with moderate physical exercise promotes the recovery of visual acuity and stereopsis in adult anisometropic amblyopes (Lunghi et al, 2018 in press). It is still unknown whether this counter-intuitive therapeutic strategy could be efficient in children and for different amblyopia etiologies (e.g. strabismus).
We combined a monocular patching of the amblyopic eye and physical activity in amblyopic (both anisometropic and strabismic) children in order to evaluate visual function recovery
Methods :
In six amblyopic children (mean age 11.5 years; four with anisometropic and strabic amblyopia and two with anisometropic amblyopia) we patched the amblyopic eye (with a translucent patch) for two hours over three consecutive days, then once per week over the next three weeks. During the patching period patients were invited to watch a movie while intermittently cycling on a stationary bicycle. Before and after each patching session we measured the best corrected visual acuity (BCVA) using LogMAR charts, stereoacuity (TNO test) and the degree of binocular vision and the presence of suppression (Worth 4 dot test)
Results :
During the four weeks of testing BCVA improved in five of the six patients. After treatment, a statistically significant (p=0.012) increase was found (mean difference=0.13 LogMAR - 95% Confidence Interval from 0.04 to 0.21). In the two non-strabic anisometropic amblyopic children, stereopsis also increased. Surprisingly, the improvement in both visual acuity and stereopsis was preserved for at least 3 months after testing. No change was found in the binocular vision assessment at the Worth 4 dot test
Conclusions :
These results demonstrate that amblyopic eye vision in children can be improved by transiently depriving the weak rather than the strong eye, probably by activating homeostatic plasticity. Physical exercise may be crucial for the recovery by potentiating the plastic potential of the visual cortex as observed in animal models (Baroncelli et al, 2012) and in humans (Lunghi et al, in press)
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.