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Jeffrey Hunter, Reed Jost, Cynthia Beauchamp, Lori Dao, Becky Luu, Ewa Niechwiej-Szwedo, Krista R Kelly; Intact hand kinematics in anisometropic children during visually-guided reaching. Invest. Ophthalmol. Vis. Sci. 2021;62(8):158.
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Coordination between eye and hand movements is essential for a child’s interaction with the environment. We previously reported longer reach times in strabismic children, and in children with impaired binocularity, compared with controls (Kelly et al, ARVO, 2019, 2020). Anisometropia results in reduced binocularity, but to a lesser extent than strabismus. Thus, reaching in anisometropic children may not be disrupted. Here, we evaluate hand kinematics during visually-guided reaching in children with anisometropia.
Results from 21 children (age 7-12 years) diagnosed with anisometropia (visual acuity, 20/16−20/630; stereoacuity, 40”–nil) were compared to 20 age-similar controls. Hand movements were recorded using the LEAP motion device. Children reached and touched a small dot that appeared in 1 of 4 positions (±5° or ±10° horizontally displaced from fixation). Kinematic measures were time-to-reach onset, reach duration, peak velocity, duration of acceleration, and duration of deceleration. Sensory factors were amblyopia (present n=15 vs not present n=5) and stereoacuity (nil n=6 vs measurable n=14).
Anisometropic children did not differ on any hand kinematic measure compared with controls (time to reach onset, 333±73 vs 334±61 ms, p=0.98; reach duration, 516±66 vs 526±47 ms, p=0.50; peak velocity, 1.35±0.24 vs 1.35±0.16 m/sec, p=0.91; duration of acceleration 187±26 vs 189±24 ms, p=0.85; duration of deceleration 324±48 vs 334±37 ms, p=0.43). Hand kinematics did not differ with sensory factors (amblyopia, stereoacuity).
Despite decorrelated binocular experience during a critical period of visuomotor development, we found no significant impact of anisometropia on hand kinematics during visually-guided reaching in children. This finding may be due to better binocularity outcomes found in anisometropic children compared with strabismic children. Children, regardless of visual deficit, may increase their speed of reaching, but pay a price with precision. Children with normal vision may improve precision and accuracy with experience, but those with abnormal vision may compensate and adapt movements (increased duration of acceleration, reduced peak velocity) to reach normal levels of accuracy and precision, as seen in adults with anisometropic amblyopia (Niechwiej-Szwedo et al, 2011). However, spatial accuracy and precision cannot be measured reliably with the LEAP device.
This is a 2021 ARVO Annual Meeting abstract.
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