Department of Health Services Research, University of Liverpool, 1-3 Brownlow Street, Liverpool, L69 3GL, UK.
Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK.
Syst Rev. 2021 Mar 27;10(1):84. doi: 10.1186/s13643-021-01634-4.
Homonymous visual field defects represent the most frequent type of visual field loss after stroke, affecting nearly 30% of individuals with unilateral post-chiasmal brain damage. This review aimed to gather the available evidence on the biomechanical changes to visual field loss following stroke.
A systematic review was conducted inclusive of randomised controlled trials, cohort studies, before-after studies and case-controlled studies. Studies including adult and paediatric participants that investigated eye, head, or body movements in post-stroke visual field loss during visual exploration tasks were included. Search terms included a range of MESH terms as well as alternative terms relating to stroke, visual field loss, hemianopia, visual functions and scanning behaviour. Articles were selected by two authors independently. Data were extracted by one author and verified by a second. All included articles were assessed for risk of bias using checklists appropriate to the study design.
Thirty-six articles (1123 participants) were included in the overall review (Kappa 0.863) and categorised into simulated or true visual field loss (typically hemianopia). Seven studies identified the biomechanical alterations to simulated hemianopia compared to normal performance. Twenty-nine studies detailed eye, head and body movement parameters in true hemianopia. Hemianopic participants and healthy adults with simulated hemianopia differed significantly from controls in various fixation and saccade parameters as indicated by increased number and duration of fixations, number and duration of saccades and scan path length with shorter mean saccadic amplitude. Under simulated hemianopia, participants were consistently biased towards the sighted visual field while gaze behaviour in true hemianopia was biased in the direction of the blind hemifield.
There is considerable evidence on the altered eye movements that occur in true hemianopia and in healthy adults with simulated hemianopia. Successful performance in naturalistic tasks of visual exploration appears to be related to compensatory mechanisms of visual exploratory behaviour, namely, an increase in the amplitude and peak velocity of saccades, widening horizontally the distribution of eye movements, and a shift of the overall distribution of saccades into the blind field. This review highlights the lack of studies reporting head and other body movement parameters in hemianopia. Further studies with robust methodology and large sample sizes involving participants with post-stroke visual field loss are needed.
PROSPERO CRD42020194403.
同视性视野缺损代表了卒中后最常见的视野丧失类型，约 30%的单侧视交叉后脑损伤患者会出现这种情况。本综述旨在收集有关卒中后视野丧失的生物力学变化的现有证据。
系统综述纳入了随机对照试验、队列研究、前后对照研究和病例对照研究。纳入的研究包括成年和儿童参与者，在视觉探索任务中，调查了卒中后视觉丧失时的眼部、头部或身体运动。检索词包括一系列 MESH 术语以及与卒中、视野丧失、偏盲、视觉功能和扫描行为相关的替代术语。由两位作者独立选择文章。一位作者提取数据，另一位作者验证。所有纳入的文章均使用适用于研究设计的检查表进行了偏倚风险评估。
总体综述纳入了 36 篇文章（1123 名参与者）（Kappa 值为 0.863），并分为模拟或真实视野丧失（通常为偏盲）。7 项研究确定了模拟偏盲与正常表现相比的生物力学变化。29 项研究详细描述了真偏盲患者的眼部、头部和身体运动参数。与对照组相比，偏盲参与者和模拟偏盲的健康成年人在各种注视和扫视参数上存在显著差异，表现为注视时间和持续时间增加、扫视次数和持续时间增加以及扫描路径长度增加，平均扫视幅度缩短。在模拟偏盲中，参与者始终偏向于有视力的视野，而真偏盲中的注视行为则偏向于无视力的视野。
有大量证据表明，在真偏盲和模拟偏盲的健康成年人中，眼球运动发生了改变。在自然视觉探索任务中的成功表现似乎与视觉探索行为的补偿机制有关，即扫视幅度和峰值速度增加，眼球运动的水平分布变宽，以及整体扫视分布向盲侧转移。本综述强调了缺乏报告偏盲患者头和其他身体运动参数的研究。需要进一步开展具有稳健方法学和大样本量的研究，纳入卒中后视野丧失的参与者。
PROSPERO CRD42020194403。
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