A new 15-minute screening tool, the Oxford Visual Perception Screen, has been developed to provide a quick and standardized assessment for visual perception impairments in stroke survivors. Researchers from Durham University and the University of Oxford validated the tool with normative data and a case series, aiming to address the limitations of existing assessments that are often lengthy and impractical in acute clinical settings.
“Tests like the Rivermead Perceptual Assessment Battery and the Occupational Therapy Adult Perception Screening Test have excellent psychometric properties,” wrote lead study author Kathleen Vancleef, of the Department of Experimental Psychology at the University of Oxford and the Department of Psychology at Durham University, with colleagues. "[However], they are not always feasible to complete with stroke survivors at the acute stage because of their length, because of reliance on verbal communication, or because cumbersome testing materials that make it difficult to complete at bedside,” they added.
The Oxford Visual Perception Screen (OxVPS) consists of 10 paper-and-pencil tasks that assess visual perception, including object and face recognition, reading, visuospatial neglect, and visuoconstructive skills. Tasks include picture naming, semantic matching, shape perception, item counting, line orientation judgment, face recognition, reading, figure copying, and a cancellation task. It is designed to accommodate common poststroke limitations such as hand weakness, fatigue, and communication difficulties. Patients can respond using pointing gestures and multiple-choice formats to minimize barriers.
The study that assessed the OxVPS included 107 neurologically healthy English-speaking older adults (mean age = 74.2 years, 45% were aged 80 years or older) to establish a standardized benchmark for normal performance and 5th percentile cut-off scores for each task. These scores served as indicators for potential visual perception impairments. Most of the participants performed near ceiling, but performance was influenced by age in the face recognition (Z = 3.61, P = .0001) and reading tasks (Z = –3.50, P = .0001). Other than the global shape perception (Z = 3.32, P = .0001) and figure copy (Z =6.57, P < .0001) tasks, there was no evidence for an effect of visual acuity on OxVPS. No significant effects were observed based on gender.
Eight patient case studies illustrated the application of OxVPS:
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Patients with severe ocular conditions such as macular degeneration failed some tasks, but their impairments couldn't be specifically screened for with the OxVPS.
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Patients with mild ocular issues or good acuity performed well across tasks.
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Three stroke survivors showed distinct profiles of impairment:
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One patient showed signs of cortical blindness despite no subjective complaints.
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Another showed evidence of prosopagnosia, alexia, visuoconstructive deficits, neglect dyslexia, akinetopsia, and achromatopsia.
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A third was indicative of optic aphasia, alexia, and neglect dyslexia.
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Among its limitations, the tool required patients to have at least 0.7 logMAR near visual acuity and a basic level of literacy for some tasks. Most normative participants were White and highly educated, which could have limited generalizability. Further research is needed to validate diagnostic accuracy, test-retest reliability, and inter-rater reliability.
In their discussion, the researchers stressed that the screening tool cannot comprehensively diagnose visual perception problems, but it can point to perceptual difficulties to support comprehensive assessment referrals and rehabilitation.
They concluded: “Following future validation research, the [OxVPS] has the potential to improve the detection of visual perception difficulties after stroke and support the planning of subsequent in-depth assessment and decisions on interim rehabilitation advice until a diagnosis is confirmed.”
A full list of disclosures can be found in the published research.
Source:
Clinical Rehabilitation
