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A new screening tool for visual perception difficulties after stroke that takes just 15 minutes to complete could help improve diagnosis of visual perception problems common in stroke survivors, new research suggested. 

The Oxford Visual Perception Screen (OxVPS) was developed at Durham and Oxford universities in the United Kingdom and contains 10 tasks including object and face recognition, item counting, and reading. Investigators said clinicians can use screening results to identify which in-depth follow-up assessments are needed and rehabilitation options.

The paper-and-pen based screen was designed to meet the need for a quick and easy-to-administer standardized assessment after stroke, lead author Kathleen Vancleef, PhD, associate professor, Department of Psychology, Durham University, Durham, the United Kingdom, told Medscape Medical News.

“There is certainly a place for the OxVPS because it will give more people access to screening for visual perception issues and will improve clinical practice compared to now, which is using more subjective assessments like observations or just asking stroke survivors if they have issues,” she said. “People aren’t always aware they have issues and in that way a lot of things are missed.”

A cross-sectional study of the OxVPS and case series were published online on February 27 in Clinical Rehabilitation.

Easy To Administer

Up to 75% of stroke survivors will have visual perception difficulties when screened with standardized assessments. However, a recent survey by the researchers showed that 94% of clinicians involved in visual perception deficit screening relied primarily on self-reports, which typically identify only about 20% of cases.

Standardized tests like the Rivermead Perceptual Assessment Battery and the Occupational Therapy Adult Perceptual Screening Test (OT-APST) are available, but Vancleef pointed out the Rivermead takes 45 minutes to 2 hours to complete. The OT-APST takes about 20 minutes to administer but relies on chunky testing materials like blocks.

To test the tool investigators conducted a cross-sectional study that included108 older adults (average age, 74.2 years; 66% women) with no history of neurological or psychiatric conditions that affect daily life. They were recruited through social media. The median time to complete the OxVPS was 20 minutes (interquartile range, 16-27 min).

Data available for 107 participants showed distributions of the scores for each task were highly skewed, with many healthy volunteers achieving the maximum score on each task.

For most tasks, the fifth centile scores can be used as the cut-off score and taken as indicative for visual perception impairment, Vancleef and colleagues said. The exceptions are the self-evaluation task and the strategy score of the figure copy task, which are evaluated qualitatively.

There was an effect of age on performance in the face recognition task (P = .003) and on reading speed in the reading task (P = .0007).

Visual acuity negatively affected performance in the global shape perception (P = .009) and the figure copy tasks (P < .001). Although visual acuity is known to decrease with age, the authors noted the correlation between the two was low, likely because visual acuity was measured with participants wearing their usual glasses or contacts.

The OxVPS was also tested in eight stroke patients, half of whom had sensory vision issues but did not have a brain injury and the other half who had a brain injury.

“What we wanted to illustrate was that our tool is sensitive to pick up brain-related visual issues, that you don’t get false positives with people who have a brain injury but might not have difficulty with seeing things because of their cataracts or their glaucoma,” said Vancleef. “The people with only cataracts or glaucoma might make a mistake or two, nothing too serious, while the people with a brain injury have clear difficulties with the tasks,” she added.

Next Steps for the OxVPS

The authors noted that the age range of the normative sample is reflective of stroke patients, nearly all participants were white, 73% had higher education, and that a strong understanding of English language was needed to complete the screening test.

A full validation study is underway in more than 200 stroke patients, with results expected later this year, Vancleef said. The OxVPS is currently available for free for publicly funded research and health care.

Individuals with basic training in therapy can learn to use the OxVPS by watching a 20-minute video, she added. “For interpretation, a stronger clinical background is required because you need to look at the results in the wider context of the patient.”

The study was funded by the National Institute for Health and Care Research and the Stroke Association through fellowships awarded to Vancleef and co-author Nele Demeyere. The authors reported no relevant conflicts of interest.