Is the ‘Visual Fields Easy’ Application a Useful Tool to Identify Visual Field Defects in Patients Who Have Suffered a Stroke?

Abstract

Aims: To determine the level of agreement between the visual Fields easy application (VFE) for iPad and a standard clinical test for assessing peripheral vision in stroke survivors. Study Design: This was a prospective cross-sectional study comparing the VFE application to the Humphrey Field Analyser (HFA) SITA Fast c30-2 program in identifying and diagnosing visual field defects post-stroke. Place and Duration of Study: The ophthalmic department at Imperial College Healthcare NHS Trust. Data collection was undertaken between January 2016 and August 2016. Methodology: A total of 50 participants with a diagnosis of stroke and a suspected visual problem were recruited to the study. Normative data was collected from 50 participants with no history of stroke or visual loss. Analysis comprised of comparing the extent of the visual field loss detected by both the VFE and HFA, and clinically assessing the results for normality. Results: Bland-Altman analysis demonstrated that with more severe visual field loss, the agreement between both modalities was found to decrease. There was a higher proportion of false negatives with the VFE compared to the HVF.  The bias towards detecting more missed test locations with the VFE application compared to the HFA was 6% for the normal participants and 2% for the stroke participants. The limits of agreement between the two modalities were large; 20% and 40% for the normal and stroke participants respectively. The sensitivity of the VFE application to determine an abnormal visual field in comparison to HFA was 88% and specificity was 76% in the stroke cohort based upon a clinical impression of its findings. The majority of stroke participants (88%) found the VFE test more comfortable to perform. Conclusion: As a screening tool, the VFE application is quick and easy to administer, preferred by patients and has good sensitivity and specificity for detecting the presence of an abnormal visual field when compared to HFA. In patients with extensive visual field loss, the VFE may overestimate visual field reduction.