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Krista R Kelly, Reed M Jost, Eileen E Birch, Sophia G Collado, Cynthia L Beauchamp, James Y Tung, Ewa Niechwiej-Szwedo; Hand kinematics in strabismic children during visually-guided reaching. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1773. doi: https://doi.org/.
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Coordination between eye and hand movements is an essential element of a child’s interaction with their environment. Decorrelated binocular experience as a result of childhood strabismus disrupts fixation and vergence stability, even when viewing binocularly (Kelly et al, Exp Eye Res, 2018), which may disrupt the maturation of eye-hand coordination. We tested the hypothesis that strabismic children would demonstrate slower hand kinematics during visually-guided reaching than controls. Clinical and sensory factors associated with reaching in strabismic children were also evaluated.
20 children (age 7-12 years) with esotropia were tested and their performance was compared to 12 age-similar controls. Strabismic children were aligned with surgery and/or glasses within 6 pd. Visual acuity and stereoacuity were tested. Medical records were reviewed for etiology and treatment history. On each trial, children binocularly viewed a fixation cross that disappeared and a 0.3° dot appeared in one of four positions (±5° or ±10° horizontally displaced from fixation) at a viewing distance of 35 cm. Children were instructed to reach out and touch the dot with the tip of their index finger as quickly and accurately as possible. Hand movements were recorded using the LEAP motion capture device. Kinematic measures were time to reach onset, reach duration, peak velocity, duration of acceleration phase (time from reach onset to peak velocity), and duration of deceleration phase (time from peak velocity to reach end).
Compared with controls (n=12, mean±SD=511±30 ms), there was a trend for reach duration to be longer in strabismic children (n=20, 540±56 ms, t30=1.91, p=0.066). For strabismic children, reach duration was longer in those with prior surgery (n=10, 552±63 ms, t20=2.01, p=0.029) compared to controls, and was due to longer duration of deceleration (surgery, 369±55 ms vs controls, 318±50 ms; t20=2.24, p=0.037). Strabismic children with no prior surgery did not have longer reach duration than controls (n=10, 527±47 ms, t20=1.00, p=0.33). In this initial analysis, we were unable to confidently identify any association between kinematic measures and non-preferred eye visual acuity or stereoacuity (all p’s≥0.21).
Decorrelated binocular experience due to childhood strabismus, especially forms that require surgery, impacts the development of eye-hand kinematics in children.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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