Abstract
Purpose :
Normal binocular vision provides important input for effective performance of manipulation tasks that involve reaching and grasping. Previous studies have shown that people with abnormal binocular vision experience difficulties with grasping; however, performance was examined using a single prehension movement. Because most daily activities consist of more complex movement sequences that require precise temporal linking between the gaze behaviour and manual actions, it is important to examine the consequences of abnormal binocular vision on the performance of sequential movements, which is the goal of this study.
Methods :
Six adults with abnormal binocular vision due to amblyopia and strabismus, and 6 visually-normal adults were tested. Participants performed a sequential reaching, grasping and precision placement task while eye movements and limb movements were recorded with a video-based eyetracker and a motion capture camera. The task involved picking up a small bead, and placing it onto a vertical needle under binocular and monocular viewing conditions. Kinematic analysis focused on 4 phases of the movement: reach-to-bead, bead grasping, reach-to-needle, and bead placement on the needle. Kinematic outcome measures were analysed using mixed Analysis of Variance with 2 factors: Group and Viewing Condition.
Results :
As expected, visually-normal participants had significantly shorter movement time (p<0.05) in comparison to the patient group for grasping and placement, while there was no difference for the reach duration to the bead or the needle. Bead placement on the needle showed the largest decrement during monocular in comparison to binocular viewing in the control group (binocular: 506±18ms; monocular: 780±26ms) and the patient group (binocular: 805±26ms; dominant eye: 960±33ms; non-dominant eye: 1021±30ms). In contrast, binocular advantage was not significant for grasping in the control group (binocular: 472±22ms; monocular: 487±20ms) or the patient group (binocular: 723±24ms; dominant eye: 812±27ms; non-dominant eye: 787±25ms).
Conclusions :
Preliminary results indicate that the performance of a manipulation task that requires high precision and action sequencing is disrupted in people with abnormal binocular vision during all viewing conditions.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.