Abstract
BackgroundHomonymous 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.MethodsA 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.ResultsThirty-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.ConclusionsThere 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.Systematic review registrationPROSPERO CRD42020194403
Highlights
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
A narrative summary of the data is presented in relation to included studies to highlight how visual field loss impacted on eye, head or body movements across the included studies
Results are split into simulated homonymous hemianopia (HH) and true Visual field defect (VFD) and discussed by type of movement analysis
Summary
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. As stroke is more common with older age, and the UK population is one of many countries with an ageing population, stroke is likely to be an ongoing health concern. A common problem post-stoke is visual impairment, with an estimated 65% of stroke survivors having visual impairment in the immediate aftermath of stroke [2]. Visual field defect (VFD) encompasses hemianopia, quadrantanopia, temporal crescent defect and scotoma, among others, with the most common defect being homonymous hemianopia (HH). HH involves vision loss on the same side of the visual field in both eyes and is associated with a worse prognosis for successful rehabilitation [5, 6], especially when combined with visual neglect [7]. 30% of stroke survivors have this visual field loss acutely while approximately 8–10% of stroke survivors have a permanent HH [8]
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