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Multicenter Comparison of the Toronto Portable Perimeter with the Humphrey Field Analyzer: A Pilot Study
Yusuf Ahmed1, Austin Pereira2, Sylvie Bowden1
1Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
Purpose:
To evaluate the agreement between glaucomatous 24-2 visual field (VF) testing performed with the Toronto Portable Perimeter (TPP; VEM Medical Technologies) and the Humphrey Field Analyzer (HFA; Carl Zeiss Meditec).
Design:
Multicenter prospective cohort analysis.
Participants:
Patients with suspected or confirmed glaucoma treated at Prism Eye Institute (Oakville, Canada), York Finch Eye Associates (North York, Canada), or the Ontario Mobile Medical Eye Care Unit (Cochrane, Canada) between March 2019 and March 2020.
Methods:
Patients underwent consecutive VF tests on the same eye using the HFA Swedish Interactive Threshold Algorithm Standard 24-2 test and TPP Standard 24-2 test in randomized order. Bland-Altman analysis and paired t tests were used to compare VF results obtained by the TPP and the HFA. Participants completed a 5-question validated questionnaire after completing both testing methods.
Main Outcome Measures:
Mean difference and degree of agreement in mean deviation (MD), pattern standard deviation (PSD), visual field index (VFI), and test duration between VF modalities.
Results:
One hundred fifty eyes from 91 patients were included in analysis. Average MD of the overall cohort using HFA and TPP VF testing was -4.32 ± 5.47 dB and -4.53 ± 5.22 dB, respectively (P = 0.74). Bland-Altman analysis showed good agreement between HFA and TPP tests. The mean differences (95% limits of agreement) between HFA and TPP for MD, PSD, VFI, and test duration were 0.21 dB (-4.25 to 4.67 dB), -0.13 dB (-3.72 to 3.47 dB), 0.66% (-10.94% to 12.26%), and 0.65 seconds (-97.51 to 98.81 seconds), respectively. No statistically significant mean difference was found between HFA and TPP tests for MD, PSD, VFI, or test duration. Mean deviation (R2 = 0.830) and VFI (R2 = 0.866) were correlated strongly with both modalities. Questionnaire results demonstrated that patients significantly preferred the TPP over the HFA for VF testing (P < 0.001).
Conclusions:
Mean deviation, PSD, and VFI outcomes measured by the TPP were statistically similar to corresponding parameters obtained with the HFA. Test time duration did not differ significantly between the TPP and HFA, and patients significantly preferred the TPP to the HFA examination experience. These pilot results suggest that the TPP may offer an accessible alternative to HFA VF testing.
