Sanz Diez Pablo, Gisbert Sandra, Bosco Annalisa, Arias Augusto, Fattori Patrizia, Wahl Siegfried
Carl Zeiss Vision International GmbH, Aalen, Germany.
Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany.
PLoS One. 2025 Sep 16;20(9):e0330223. doi: 10.1371/journal.pone.0330223. eCollection 2025.
Impairments of visual function abilities, such as visual acuity and contrast sensitivity, can negatively impact our ability to perform manual prehension tasks. Despite the clear link between visual input and motor output, there is still limited understanding of how visual function deficits affect hand motor behavior. This study aimed to explore the impact of different levels of visual function degradation, specifically in terms of visual acuity and contrast sensitivity, on the reach and grasp components of manual prehension. To this end, visual function degradation was induced in young participants with normal vision using five different densities of Bangerter occlusion foils. Participants were instructed to perform a natural and accurate reach-to-grasp task towards a cylindrical object with two different diameters (3.5 or 7 cm) and positioned at two distances (25 or 50 cm). The effects of visual function degradation, object size, and distance were evaluated by recording the position and trajectory of the right hand using an optoelectronic motion capture system. Three-dimensional kinematic analysis revealed that visual function degradation in normal-sighted individuals directly altered the reach and grasp components of prehension movements. These alterations included longer movement durations, lower velocity and acceleration profiles, slower deceleration phases, over-scaled hand grip apertures, and greater trajectory deviations. The effects were dependent on the level of visual degradation induced and the intrinsic (size) and extrinsic (distance) object properties. Reductions exceeding 70% in visual acuity and 55% in CS had the most pronounced impact on prehension components. However, subtle reductions greater than 30% in visual acuity and 15% in contrast sensitivity were sufficient to trigger compensatory mechanisms. These findings provide further understanding of how visual function degradation affects prehension movement strategies, highlighting the crucial relationship between visual feedback quality and object properties in the motor online control of the transport, manipulation and spatial components. Our results offer new insights into the implications of visual impairments on manual prehension movements.
视觉功能能力的损害，如视力和对比敏感度，会对我们执行手动抓握任务的能力产生负面影响。尽管视觉输入与运动输出之间存在明显联系，但对于视觉功能缺陷如何影响手部运动行为的理解仍然有限。本研究旨在探讨不同程度的视觉功能退化，特别是在视力和对比敏感度方面，对手动抓握的伸展和抓握部分的影响。为此，使用五种不同密度的班格特遮挡箔片，在视力正常的年轻参与者中诱导视觉功能退化。参与者被要求对两个不同直径（3.5或7厘米）、位于两个距离（25或50厘米）的圆柱形物体执行自然而准确的伸手抓握任务。通过使用光电运动捕捉系统记录右手的位置和轨迹，评估视觉功能退化、物体大小和距离的影响。三维运动学分析表明，视力正常个体的视觉功能退化直接改变了抓握动作的伸展和抓握部分。这些改变包括更长的运动持续时间、更低的速度和加速度曲线、更慢的减速阶段、过度缩放的手握孔径以及更大的轨迹偏差。这些影响取决于诱导的视觉退化程度以及物体的内在（大小）和外在（距离）属性。视力下降超过70%和对比敏感度下降超过55%对抓握部分的影响最为明显。然而，视力下降大于30%和对比敏感度下降大于15%的细微降低就足以触发补偿机制。这些发现进一步加深了我们对视觉功能退化如何影响抓握运动策略的理解，突出了视觉反馈质量与物体属性在运输、操作和空间组件的运动在线控制中的关键关系。我们的结果为视觉障碍对手动抓握运动的影响提供了新的见解。
