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R.W. Li, K.G. Young, P. Hoenig, J. Nguyen, D.M. Levi; Perceptual Learning Improves Visual Performance in Children With Amblyopia . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5646.
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Purpose: To ask whether practicing a position discrimination task can improve visual performance in children with amblyopia. Methods: In this experiment, 4 children (ages 7 to 10, mean age: 8.7 years) with strabismic and/or anisometropic amblyopia (crowded visual acuity: 20/32 to <20/100) practiced a positional acuity task in which they had to judge which of three pairs of lines was misaligned. The stimulus was comprised of two segments with a 17 (2 m) or 34 (1 m) arcmin gap. Each segment consisted of eight discrete Gabor patches. Positional noise was produced by distributing the individual patches of each segment according to a Gaussian probability function. Observers were trained at three noise levels (including zero). Trial–by–trial feedback was provided. Each observer had given more than 4000 responses at the end of the experiment (10 sessions, 1.5 hours each, in about 5–8 weeks). Results: We found that 3 of the 4 observers showed significant improvements in positional acuity. For those three observers, on average position acuity with no noise improved by about 26%, and with high noise by about 21%. We used a position averaging model to parse the improvement into an increase in efficiency or a decrease in equivalent input noise. Two observers showed increased efficiency (51% and 117% improvement) with no significant change in equivalent input noise across sessions; and one observer showed both a decrease in equivalent input noise (18%) and an increase in efficiency (17%). Interestingly all four amblyopic observers showed substantial improvement in Snellen acuity (about 30% for both single letter and line acuities) following practice. Conclusions: Here we show that amblyopic children have a significant degree of plasticity. We were able to attribute the improvement to two important factors: decreased equivalent input noise and increased efficiency. We speculate that perceptual learning techniques may add an effective new method to the armamentarium of treatment for childhood amblyopia.
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