Development of V-FAST: a vision screening tool for ambulance staff

Background: About two-thirds of stroke survivors experience visual problems and most patients who have a stroke limited to the occipital lobe will have visual impairments only. Aim: The V-FAST screening tool, which assesses visual symptoms, eye movements, visual field and visual extinction, and a training package to improve diagnostic accuracy of identifying visual impairment in hyperacute strokes were developed and evaluated. Methods: The educational package was developed through focus groups. The pilot study screened patients with suspected strokes in prehospital settings; the V-FAST tool was used with 43 of these patients. Each participant was also assessed in hospital using the National Institutes of Health Stroke Scale (NIHSS) and the score compared to V-FAST screening results to determine sensitivity and specificity. Results: The education package includes detailed instructions with video. In the pilot study, V-FAST detected visual impairment in 75.9% of FAST-positive and 80% of FAST-negative strokes. Sensitivity and specificity compared to NIHSS were 85.7% and 42.1% respectively. Conclusion: V-FAST has good sensitivity to detect vision impairment when screening for possible strokes. The added education package facilitates greater knowledge and understanding of potential visual problems caused by stroke.