Comparison of Humphrey Field Analyzer and imo visual field test results in patients with glaucoma and pseudo-fixation loss

The aim of this cross-sectional study was to evaluate the results of a visual field (VF) test for patients with glaucoma and pseudo-fixation loss. These patients exhibit fixation loss (FL) rates >20% with the Humphrey Field Analyzer (HFA); however, actual fixation stabilizes when a head-mounted perimeter (imo) is used. This device is able to adjust the stimulus presentation point by tracking eye movements. We subjected 54 eyes of 54 patients with glaucoma and pseudo-FL to the HFA 30–2 or 24–2 Swedish Interactive Threshold Algorithm -Standard protocol. All patients also underwent the imo 30–2 or 24–2 Ambient Interactive Zipper Estimated Sequential Testing protocol after HFA measurement. We compared HFA and imo reliability indices [including false-positive (FP) responses, false-negative (FN) responses, and FL rate], global indices [including mean deviation (MD), visual field index (VFI), and pattern standard deviation (PSD)], and retinal sensitivity for each test point. There were no significant differences in MD, VFI, and PSD between HFA and imo, and these measures were strongly correlated (r > 0.96, p < 0.01). There were no significant differences in FP and FN between both devices, while FL measured with HFA (27.5%) was significantly reduced when measured with imo (13.2%) (p < 0.01). There was no correlation in FL and FN between both devices, and a weak correlation for FP (r = 0.29, p = 0.04). At each test point, retinal sensitivity averaged 1.7 dB higher with HFA, compared with imo (p < 0.01). There was no significant variability in global indices in patients with pseudo-FL. The FP response rate might have influenced measures of FL in patients with glaucoma and pseudo-FL.