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.
Highlights
Stroke is a common condition in the United Kingdom, estimated to occur in approximately 152,000 people per annum [1] and is a leading cause of adult disability [2]
A total of 51 patients were recruited into the study, one patient was able to complete the iPad assessment but not able to sit at the Humphrey Field Analyser (HFA) and was excluded at that point
The results suggest that the visual Fields easy application (VFE) is a promising screening tool for visual field assessment in stroke survivors but is not intended to replace standard perimetry
Summary
Stroke is a common condition in the United Kingdom, estimated to occur in approximately 152,000 people per annum [1] and is a leading cause of adult disability [2]. Any visual dysfunction following stroke can affect the overall rehabilitation of the patient and their overall quality of life [3,4,5,6]. 60% of patients suffer visual impairment immediately post-stroke [3,7,8]. The diagnostic accuracy of referrals by the multidisciplinary stroke team is lower when there are no visible ocular ‘signs’ of dysfunction such as with visual field loss [16]. It is acknowledged that many stroke patients are not referred for a visual assessment, as a problem is not suspected. 10% of stroke patients with a visual field defect are not subjectively aware of a problem [3]
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