Abstract
Research on interocular synchronicity in amblyopia has demonstrated a deficit in synchronization (i.e. a neural processing delay) between the two eyes. Current methods for assessing interocular delay are either costly or only effective for assessments in mild amblyopia. In this study, we adapted a novel protocol developed by Burge & Cormack (2020) based on continuous psychophysics to measure the interocular delay on a wide range of amblyopes. The purpose of the current study is to assess the efficacy and accessibility of this protocol and determine whether the measurements of interocular synchronicity it produces are correlated with visual acuity. This protocol is performed in both binocular and monocular viewing conditions and consists of following a target undergoing lateral Brownian motion as closely as possible with the mouse curser. The lag between the target and cursor is computed for each eye by determining the offset between the stimulus and mouse sequence at which the cross-correlation coefficient is maximal. This lag reflects the processing delay for a given eye. Additionally, assessment of the quality of the correlation indicates the accuracy at which the target was tracked. Our results show that all but the most severe amblyopes successfully performed this task and exhibited interocular delay ranging from 1.6ms to 125.3ms. For the majority of amblyopes, this delay was attributed to the amblyopic eye. The correlations used to determine delays were generally high in quality but were lower in quality for the amblyopic eye. The magnitude of the delay was positively correlated with larger differences in interocular visual acuity. These results demonstrate the efficacy of this new protocol and further support the link between interocular synchronicity and amblyopia. These results could lead to the development of a universal interocular assessment procedure for diagnostic purposes.