Abstract: Purpose. We investigated how temporal processing within and between eye was affected in amblyopia by comparing temporal synchrony sensitivity at the binocular, monocular, and dichoptic viewing conditions.
Methods. Eight anisometropic amblyopia (23.68±2.86y) and 11 age-matched normal controls（24.33±2.14y）participated. Stimuli were generated using a Macintosh computer and displayed on a GOOVIS 3D goggles. The stimuli consisted of four Gaussian blobs each flickering at 1Hz, with two spots presented at the top and the other two spots at the bottom of the screen. Subjects were asked to determine which pair of spots (top or bottom) were flickering asynchronously. Constant stimuli method was used to measure the minimum degrees of asynchrony that allowed subjects to discriminate which pair of the blobs was flickering asynchronously in time (synchrony thresholds). Six synchrony thresholds were compared: (1) binocular viewing where the four spots were presented to both eyes; (2) monocular amblyopic viewing where the four spots were presented to amblyopic (non-dominant) eye; (3) monocular fellow eye viewing where the four spots were presented in the fellow (dominant) eye; (4) dichoptic amblyopic viewing where the two asynchrony spots were presented to amblyopic eye and the two synchrony spots were presented to fellow eye; (5) dichoptic fellow eye viewing where the two asynchrony spots were presented to fellow fixing eye; and (6) pure dichoptic viewing where the paired spots were presented to different eyes.
Results. Repeated-measure ANOVA showed that the synchrony threshold was significantly different among conditions (F(2.37,42.661) =7.228,p=0.001), and such difference was significantly different in different groups as the joint effect between condition and groups was significant (?F(2.37,42.661) =5.853,P=0.004). Post-hoc test further showed that synchrony thresholds were significantly higher for amblyopic subjects comparing to normal controls under monocular amblyopic viewing (P = 0.027) and pure dichoptic viewing condition (P = 0.049). The slope of the psychometric functions were not significantly different between groups (F(1,18) =2.033,p=0.171).
Conclusions. Our results suggest that there are within eye and between eye temporal synchrony deficits in amblyopia.