Owsley C, Ball K, Keeton D M
Department of Ophthalmology, School of Medicine/Eye Foundation Hospital, University of Alabama at Birmingham 35294-0009.
Vision Res. 1995 Feb;35(4):579-87. doi: 10.1016/0042-6989(94)00166-j.
Older adults commonly report problems in visual search tasks and experience a higher incidence of mobility problems (e.g. falls and vehicle crashes), which involve visual skills. We examined whether target localization problems in the elderly can be adequately explained by impairments in peripheral visual sensitivity, or whether deficits in higher order visual processing are also contributory. Fifty-nine older adults (59-88 yr) who exhibited varying degrees of visual field loss (none to severe) were asked to localize briefly-presented, high-contrast targets (3 x 5 deg) in the central 60 deg (diameter) of the visual field, while simultaneously performing a visual discrimination task at fixation. Visual sensitivity accounted for only 36% of the variance in localization performance across subjects, and this relationship grew weaker (13%) when the target was embedded in distracting stimuli, suggesting that impaired attentional skills also underlie older adults' localization problems. Not surprisingly, older adults with severe visual field loss were also poor at localizing targets. However, about half of those older patients with normal or near-normal visual fields also had severe localization problems. These results indicate that despite having good visual field sensitivity, many older adults have serious difficulty locating objects of interest in the environment. This study illustrates that clinical tests for identifying visual performance problems in the elderly must embody stimulus and task features which better reflect the visual demands of everyday life.
老年人通常表示在视觉搜索任务中存在问题，并且遭遇行动不便问题（如跌倒和车祸）的几率更高，而这些问题都涉及视觉技能。我们研究了老年人的目标定位问题能否完全由周边视觉敏感度受损来解释，或者高阶视觉处理缺陷是否也有影响。我们要求59名年龄在59至88岁之间、呈现出不同程度视野缺损（从无到严重）的老年人在视野中心60度（直径）范围内定位短暂呈现的高对比度目标（3×5度），同时在注视点进行视觉辨别任务。视觉敏感度仅占受试者间定位表现差异的36%，当目标嵌入干扰刺激中时，这种关系变得更弱（13%），这表明注意力技能受损也是老年人定位问题的潜在原因。不出所料，视野严重缺损的老年人在目标定位方面也很差。然而，那些视野正常或接近正常的老年患者中，约有一半也存在严重的定位问题。这些结果表明，尽管许多老年人具有良好的视野敏感度，但他们在定位环境中感兴趣的物体时仍存在严重困难。这项研究表明，用于识别老年人视觉表现问题的临床测试必须体现出能更好反映日常生活视觉需求的刺激和任务特征。
