Saccade testing to distinguish between non-organic and organic visual-field restriction.

AIM The authors described and tested a simple bedside procedure to detect non-organic visual-field loss. METHODS Prospective comparative observational case series of 16 patients with non-organic visual-field loss and 15 patients with organic visual-field loss were examined. Saccade patterns provoked by a stimulus outside the claimed visual field were assessed by a masked observer. RESULTS Whereas, in organic visual-field defects, eye movements as noted by the observer were in small and erratic searching patterns towards the visual-field defect in all patients (15/15), most patients with non-organic visual-field loss (14/16) were able to jump directly to the presented red cap in one directional large saccade, although the stimulus was outside their stated visual field. The sensitivity of the saccade test in detection of non-organic visual-field loss by a masked observer was 87% (95% CI 60% to 97%) and the specificity was 100% (95% CI 75% to 100%). The positive predictive value for non-organic visual-field loss of the saccade test was 100%, and the negative predictive value was 90%. CONCLUSIONS The saccade test is a quick and reproducible examination to use and is largely independent of the patient's willingness for cooperation. The authors believe that the test will be of value to clinicians on bedside evaluation when non-organic visual-field loss is suspected.