Motion-in-depth Perception and Static Stereopsis of Patients with Strabismics

Objective To determine the role of motion-in-depth perception and static stereopsis in strabismics, and factors associated with the perception of motion-in-depth. Methods A total of 84 strabismic patients (including 57 intermittent exotropes, 12 constant exotropes and 15 esotropes) and 16 normal controls were recruited. Binocular fusion ability, static stereopsis and motion-in-depth perception were tested using the computer-generated stereoscopic stimuli. The correlations between these tests were analyzed. Results There was a significant correlation between motion-in-depth perception and static stereopsis in strabismics. Only patients with static stereopsis demonstrated the perception of motion-in-depth. A positive correlation was found between motion-in-depth perception thresholds and static stereopsis in intermittent exotropes. All participants in the control group had motion-in-depth perception and static stereopsis. The participants with stereopsis had significantly lower thresholds than those with strabismus (P<0.01). The perception of motion-in-depth varied with the type of strabismus: 87.7% of the intermittent exotropes exhibited motion-in-depth perception, whereas none of the constant strabismics were able to pass the motion-in-depth perception tests. The perception of motion-in-depth was correlated with the presence of binocular fusion. Conclusions Motion-in-depth perception is correlated with static stereopsis in strabismics. The perception of motion-in-depth varies with the type of strabismus: only intermittent exotropes have the perception of motion-in-depth.