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Zidong Chen, Jinrong Li, Junpeng Yuan, Daming Deng, Minbin Yu; Effect of monocular perceptual learning on binocular combination in anisometropic amblyopia. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2192. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual learning of contrast detection can improve monocular visual function in adult amblyopes (Huang, 2008, PNAS). The effect of such training paradigm on binocular combination condition remains unknown. This study aimed to assess the binocular combination outcome after monocular perceptual learning in anisometropic amblyopes beyond critical period.
Ten young participants with anisometropic amblyopia (age: 8-20) performed 2AFC grating contrast detection task near cut-off spatial frequency in the amblyopic eye for 7-12 days. Contrast sensitivity function (CSF), binocular function measurement using (1) binocular phase combination, (2) global dichoptic motion coherence, visual acuity (VA), and randot stereo acuity were assessed before and after training. Another ten subjects with anisometropic amblyopia (age: 7-16) prescribed patching for 4h/d and followed up in 2 weeks served as control.
Monocular perceptual learning significantly improved visual acuity in the amblyopic eye (1.68±0.08 lines, P=0.0002) and contrast sensitivity (CS) at trained spatial frequency (8.83±3.04 dB, P=0.0001). Change of binocular combination was observed by measuring effective contrast ratio (ECR) in (1) binocular phase combination task at spatial frequency of 0.3 cycle per degree (P=0.015; N=10), and (2) dichoptic motion coherence task (P=0.013; N=8). Area under log CSF (AULCSF) was calculated. Improvement of AULCSF in the amblyopic eye was found to be correlated with the improvement of ECR in binocular phase combination task (R=0.733, P=0.016) and VA (R=0.71,P=0.021). Change of binocularly perceived phase after training was observed only when low contrast stimuli was presented to the non-amblyopic eye, but not when higher contrast stimuli was used. Patching group didn’t show significant improvement in either visual acuity or binocular combination in 2 weeks.
Monocular perceptual learning in anisometropic amblyopia could improve visual acuity in amblyopic eyes and change binocular combination condition. Improvement of CSF may be the underlying mechanism. However, such training paradigm was not sufficient to establish normal binocular vision in amblyopes when images of identical contrast were presented to both eyes.
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