Abnormal Monocular and Dichoptic Temporal Synchrony in Adults with Amblyopia

Abstract

Citation: Tao C, Wu Y, Gong L, et al. Abnormal monocular and dichoptic temporal synchrony in adults with amblyopia. Invest Ophthalmol Vis Sci. 2019;60:4858-4864. https://doi.org/ 10.1167/iovs.19-27893 PURPOSE. We investigate temporal synchrony within one eye and between both eyes in adults with amblyopia. (range, 19.88-27.81 years old; median, 22.86 years old) and 12 age-matched adults with normal vision (range, 21.2-50.30 years old; median, 23.78 years old) participated in the experiment. We showed two pairs of Gaussian blobs flickering at 1 Hz as visual stimuli, one pair with the same temporal phase modulation (i.e., the reference) and another pair with a distinct temporal phase (i.e., the signal). We employed the constant stimuli method to measure the minimum degree of temporal phase (temporal synchrony threshold), at which participants were able to discriminate the signal pair under binocular, monocular, and dichoptic viewing configurations. METHODS. Eight adult amblyopesRESULTS. The temporal synchrony threshold was different across the six configurations (P ¼ 0.001). There was also an interaction between the configuration and the group (P ¼ 0.004). The synchrony threshold was significantly higher in amblyopes than in controls under the configurations where two pairs of blobs were presented to the amblyopic eye (136.52 6 50.19 vs. 97.08 6 22.02 ms, P ¼ 0.027) and where the paired blobs were presented to different eyes (163.15 6 80.85 vs. 111.61 6 22.46 ms, P ¼ 0.049). The visual deficits in these two configurations were significantly correlated (r ¼ 0.824, P ¼ 0.012).CONCLUSIONS. The threshold for detecting temporal asynchrony increased when the stimuli were presented only to the amblyopic eye and when they were dichoptically presented to the amblyopic and fellow eyes.

Reduced Monocular Luminance Increases Monocular Temporal Synchrony Threshold in Human Adults

“…49,55 The abnormalities of connections linking neurons have been suggested to be the reason for reduced synchronization in amblyopic eyes. 56 The abnormal temporal synchrony in patients with amblyopia also has been observed recently by Tao et al 38 It is probable that neuronal connections might be disrupted at reduced luminance, thereby manifesting an increase in the threshold for temporal synchrony discrimination.…”

“…Similar to our previous study 38 using a similar synchrony paradigm, we assumed that the psychometric slopes were equal (i.e. reduced fitting model) in the six viewing configurations (i.e.…”

“…35 Both the monocular and binocular visual systems have been shown to be involved in processing temporal information by grouping common elements. 36,37 In our study, we used a psychophysical task, which was introduced by Tao et al, 38 to study the role of reduced luminance in one eye on the perception of monocular and dichoptic temporal synchrony in amblyopes. For the performance metric of observers, we estimated the threshold at which the observers could distinguish between asynchronous stimuli and synchronous stimuli.…”

Interocular Suppression as Revealed by Dichoptic Masking Is Orientation-Dependent and Imbalanced in Amblyopia

“…6,7 Amblyopes also suffer from reduced visual performance for stereopsis, 8 binocular combination, 9 face perception, 10 global motion perception, 11 global form perception, 12 and temporal synchrony detection. 13 Recent studies suggest that binocular vision deficits are more impactful than monocular vision deficits in amblyopes' daily life. 3,14 Interocular suppression plays a key role in the binocular visual deficits of amblyopes.…”

Two Patterns of Interocular Delay Revealed by Spontaneous Motion-in-Depth Pulfrich Phenomenon in Amblyopes with Stereopsis

“…Recently, Tao et al 51 showed that there are temporal synchrony deficits within the eye and between eyes in amblyopia. They found that the temporal synchrony thresholds of amblyopes under dichoptic viewing was significantly higher than that under monocular configuration.…”