SCALab, University of Lille, National Center for Scientific Research, Lille, France.
Ophthalmology Department, Lille Catholic Hospitals, Catholic University of Lille, Lille, France.
Clin Exp Optom. 2020 Sep;103(5):648-655. doi: 10.1111/cxo.12982. Epub 2019 Nov 7.
Visual search, an activity that relies on central vision, is frequent in daily life. This study investigates the effect of spacing between items in an object search task in participants with central vision loss.
Patients with neovascular age-related macular degeneration (AMD), age-matched controls, and young controls were included. The stimuli were displays of four, six and nine objects randomly presented in a 'crowded' (spacing 1.5°) or 'uncrowded' (spacing 6°) condition. For each of 96 trials, participants were asked to search for a predefined target that remained on the screen until the response was recorded. Accuracy, search time, and eye movements (number of fixations and scan path ratio) were recorded.
Compared to older controls, accuracy decreased by 31 per cent and search time increased by 61 per cent in AMD participants. Ageing also affected performance with a lower accuracy by 13.5 per cent and longer search times by 46 per cent in older compared to younger controls. Increasing the spacing between elements increased accuracy by 21 per cent in AMD participants but it had no effect in older and younger controls. Performance was not related to visual acuity or to duration of neovascular AMD, but search time was correlated to the lesion size in the 'crowded' condition.
Object search is ubiquitous in daily life activities. When visual acuity is irrevocably reduced, increasing the spacing between elements can reliably improve object search performance in patients.
视觉搜索是一种依赖于中央视觉的活动，在日常生活中很常见。本研究调查了在中央视力丧失的参与者中，在目标搜索任务中项目之间的间隔对搜索表现的影响。
纳入了新生血管性年龄相关性黄斑变性（AMD）患者、年龄匹配的对照组和年轻对照组。刺激物是随机呈现的四个、六个和九个物体的显示，呈现条件为“拥挤”（间隔 1.5°）或“不拥挤”（间隔 6°）。对于 96 次试验中的每一次，要求参与者搜索预定义的目标，该目标会一直留在屏幕上，直到记录响应。记录准确性、搜索时间和眼动（注视次数和扫描路径比）。
与年龄匹配的对照组相比，AMD 患者的准确性降低了 31%，搜索时间增加了 61%。随着年龄的增长，老年人的表现也受到影响，准确性降低了 13.5%，搜索时间延长了 46%。与年龄匹配的和年轻的对照组相比，增加元素之间的间隔使 AMD 患者的准确性提高了 21%，但对老年人和年轻人对照组没有影响。表现与视力或新生血管性 AMD 的持续时间无关，但在“拥挤”条件下，搜索时间与病变大小相关。
目标搜索是日常生活活动中无处不在的。当视力不可逆转地下降时，增加元素之间的间隔可以可靠地提高患者的目标搜索表现。
