Effect of a patient educational video on visual field test reliability

Abstract

Purpose: Standard automated perimetry (SAP) is the gold standard for detecting and monitoring visual field (VF) defects in glaucoma, but frequent re-testing due to unreliable results increase the burden on this frequently used service. This study aims to assess the reliability of the Humphrey visual field (HVF) test in glaucoma-suspect patients with no previous SAP experience and to determine the effect of a VF test educational video on reliability.
Study design: The study was conducted as a full cycle audit.
Methods: The audit cycle was carried out in four phases: pre-intervention audit, intervention, monitoring, and post-intervention audit. The pre-intervention audit was carried out from January 2020 to May 2020 and the post-intervention audit was carried out from September 2020 to December 2020. The intervention was in the form of a VF test educational video. A post-video assessment pertaining to the contents of the video was given to patients in the intervention group to complete after they watched the video. The results were then tabulated and analysed.
Results: The pre-intervention audit showed that only 66.7% of glaucoma-suspect patients with no previous SAP experience had reliable HVF tests. Post-intervention, HVF reliability improved to 87.5% of patients. Based on the reliability parameters, the main reason for the HVF test being classified as unreliable in both the pre- and post-intervention was fixation loss greater than 20% in 36 (90%) and 11 (73.3%) patients, respectively. There were 76.9% of patients with unreliable fields who had < 4 correct answers on the post-video assessment; all patients who had > 4 correct answers had reliable HVF results.
Conclusion: HVF reliability performance in glaucoma-suspect patients improved with the introduction of a pre-test educational video. It is a simple and inexpensive method which may reduce the need for repeat HVF tests for those with unreliable tests.