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Jun-Yun Zhang, Yu-Xiang Yang, Stanley Klein, Dennis Levi, Cong Yu; Push-pull training suppresses the interocular suppression in amblyopic vision. Journal of Vision 2013;13(9):1092. doi: 10.1167/13.9.1092.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Amblyopia is characterized by poor visual acuity in the amblyopic eye (AE) and degraded stereoacuity. Perceptual learning, in which observers practice visual discrimination with their AEs, improves these visual functions to some degree. Here we asked whether a push-pull training method would reduce interocular suppression, in order to further improve visual acuity and stereoacuity in amblyopes who have previously participated in many hours of perceptual learning experiments. Methods: In push-pull training, AE practiced contrast discrimination with two 45° Gabors (SF=1/2 cutoff frequency) whose contrasts differed by 1.5 times threshold while non-amblyopic eye (NAE) was presented with bandpass noise (centered at 1/2 cutoff frequency). A staircase measured the tolerable noise contrast in NAE to allow successful contrast discrimination in AE during push-pull training. In pre- and post-tests, AE and NAE stimuli were switched to measure the tolerable noise contrast in AE. Interocular suppression was defined by the difference between AE and NAE tolerable noise contrasts. Results: After 10-days (20-hrs) training, interocular suppression was reduced by 57.3% (p<0.001). This reduction was specific to the trained orientation (12.9% improvement with 135° Gabors, p=0.36) and task (0.3% improvement in tumbling-E orientation judgment, p=0.43), but the tolerable noise contrast in NAE was reduced by 49.3% (p=0.015) with a new bandpass noise at a 2-octave lower center frequency. Stereoacuity was improved by 25.2% (p=0.001), on top of the 54.7% improvement after perceptual learning, but AE visual acuity was not further improved (by 1.5%, p=0.33). Conclusion: Our results show that push-pull training can suppress interocular suppression in an orientation and task specific manner in amblyopes even after many hours of previous perceptual learning experiments. Push-pull training further improves stereoacuity, but has no extra impact on AE visual acuity.
Meeting abstract presented at VSS 2013
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