Niechwiej-Szwedo Ewa, Goltz Herbert C, Chandrakumar Manokaraananthan, Wong Agnes M F
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada University of Toronto, Toronto, Ontario, Canada.
Invest Ophthalmol Vis Sci. 2014 Nov 11;55(12):7831-8. doi: 10.1167/iovs.14-15507.
To examine the effects of strabismic amblyopia and strabismus only, without amblyopia, on the temporal patterns of eye-hand coordination during both the planning and execution stages of visually-guided reaching.
Forty-six adults (16 with strabismic amblyopia, 14 with strabismus only, and 16 visually normal) executed reach-to-touch movements toward targets presented randomly 5° or 10° to the left or right of central fixation. Viewing conditions were binocular, monocular viewing with the amblyopic eye, and monocular viewing with the fellow eye (dominant and nondominant viewing for participants without amblyopia). Temporal coordination between eye and hand movements was examined during reach planning (interval between the initiation of saccade and reaching, i.e., saccade-to-reach planning interval) and reach execution (interval between the initiation of saccade and reach peak velocity [PV], i.e., saccade-to-reach PV interval). The frequency and dynamics of secondary reach-related saccades were also examined.
The temporal patterns of eye-hand coordination prior to reach initiation were comparable among participants with strabismic amblyopia, strabismus only, and visually normal adults. However, the reach acceleration phase of participants with strabismic amblyopia and those with strabismus only were longer following target fixation (saccade-to-reach PV interval) than that of visually normal participants (P < 0.05). This effect was evident under all viewing conditions. The saccade-to-reach planning interval and the saccade-to-reach PV interval were not significantly different among participants with amblyopia with different levels of acuity and stereo acuity loss. Participants with strabismic amblyopia and strabismus only initiated secondary reach-related saccades significantly more frequently than visually normal participants. The amplitude and peak velocity of these saccades were significantly greater during amblyopic eye viewing in participants with amblyopia who also had negative stereopsis.
Adults with strabismic amblyopia and strabismus only showed an altered pattern of temporal eye-hand coordination during the reach acceleration phase, which might affect their ability to modify reach trajectory using early online control. Secondary reach-related saccades may provide a compensatory mechanism with which to facilitate the late online control process in order to ensure relatively good reaching performance during binocular and fellow eye viewing.
研究仅患有斜视性弱视以及仅患有斜视（无弱视）对视觉引导伸手动作的计划和执行阶段中眼手协调时间模式的影响。
46名成年人（16名患有斜视性弱视，14名仅患有斜视，16名视力正常）向随机出现在中央注视点左侧或右侧5°或10°的目标执行伸手触摸动作。观察条件包括双眼观察、用弱视眼单眼观察以及用对侧眼单眼观察（对于无弱视的参与者为优势眼和非优势眼观察）。在伸手计划阶段（扫视开始与伸手之间的间隔，即扫视至伸手计划间隔）和伸手执行阶段（扫视开始与伸手峰值速度[PV]之间的间隔，即扫视至伸手PV间隔）检查眼动和手动之间的时间协调性。还检查了与伸手相关的二次扫视的频率和动态。
患有斜视性弱视、仅患有斜视的参与者以及视力正常的成年人在伸手开始前的眼手协调时间模式相当。然而，患有斜视性弱视和仅患有斜视的参与者在目标固定后（扫视至伸手PV间隔）的伸手加速阶段比视力正常的参与者更长（P<0.05）。在所有观察条件下这种效应均明显。在不同视力和立体视敏锐度丧失水平的弱视参与者中，扫视至伸手计划间隔和扫视至伸手PV间隔无显著差异。患有斜视性弱视和仅患有斜视的参与者比视力正常的参与者发起与伸手相关的二次扫视的频率明显更高。在同时具有负立体视的弱视参与者中，在用弱视眼观察期间这些扫视的幅度和峰值速度明显更大。
仅患有斜视性弱视和斜视的成年人在伸手加速阶段表现出时间性眼手协调模式改变，这可能会影响他们使用早期在线控制来修改伸手轨迹的能力。与伸手相关的二次扫视可能提供一种补偿机制，以促进后期在线控制过程，从而在双眼和对侧眼观察期间确保相对良好的伸手表现。
