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Sabrina Hou, Yu Yan Zhang, Lisa Christian, Ewa Niechwiej-Szwedo, Deborah Giaschi; Evaluating visuomotor coordination in children with amblyopia. Journal of Vision 2021;21(9):1999. doi: https://doi.org/10.1167/jov.21.9.1999.
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© ARVO (1962-2015); The Authors (2016-present)
Amblyopia is a visual developmental disorder characterized by poor visual acuity in one eye that cannot be immediately corrected with lenses. Amblyopia is associated with deficits attributed to vulnerability in the dorsal visual stream, including stereoscopic depth perception, motion perception, visuomotor coordination, and reading. Adults with amblyopia show deficits on reaching and grasping tasks, but less is known about visuomotor deficits in children, specifically, for complex tasks that require movement sequencing. Our aim was to assess hand-movement kinematics for a precision reaching and grasping task in children with amblyopia or strabismus. Visual acuity, stereoacuity, and fine motor coordination were assessed in 276 children ages 5-14 (21 with amblyopia or strabismus; 256 age-matched controls). A bead-threading task was conducted under binocular viewing and involved 30 trials of a sequence of 4 movements: reach‐to‐bead, grasp bead, reach‐to‐needle, thread onto needle. A Leap Motion tracker recorded hand movement. The main outcome measures were reach duration, peak velocity, acceleration and deceleration intervals of each movement, grasp and thread duration, as well as total movement time. The amblyopia group showed significantly longer durations than the control group on the grasp (z-score 0.77 vs. 0.00), thread (0.48 vs. -0.01), and total movement (0.56 vs. 0.00) parameters. Based on the maturation age for these parameters in the control children, the groups were then split into immature (ages 5-9) and mature groups (ages 10-14). Grasp duration was longer in both mature and immature amblyopia groups; thread and total movement durations were longer in the mature amblyopia group only. Stereoacuity, but not visual acuity, was significantly correlated with grasp, thread, acceleration and total movement durations for the full participant group. Grasp duration was the most disrupted kinematic parameter in children with amblyopia, regardless of age. Binocular vision rather than depth of amblyopia may determine the severity of visuomotor deficits.
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