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Advanced Vision Analyzer-Virtual Reality Perimeter: Device Validation, Functional Correlation and Comparison with
Priya Narang1, Amar Agarwal2, Maheswari Srinivasan2
1Refractive & Glaucoma Services, Narang Eye Care & Laser Centre, Ahmedabad, India.
Purpose:
To evaluate the Advanced Vision Analyzer (AVA; Elisar Vision Technology) and to compare pointwise threshold sensitivity and functional correlation of Elisar Standard Algorithm (ESA) with the Swedish Interactive Threshold Algorithm (SITA) of the Humphrey Field Analyzer (HFA; Carl Zeiss Meditec, Inc).
Design:
Prospective, cross-sectional, observational case series.
Participants:
One hundred sixty eyes (85 control participants, 75 glaucoma patients) for functional assessment, 15 eyes for test-retest variability (TRV), 107 eyes for blind spot trial (45 normal eyes, 62 glaucoma eyes) were recruited consecutively. A separate group of participants was chosen for each assessment.
Methods:
All participants underwent ESA and SITA Standard 24-2 testing, and 1 eye of each participant was selected randomly. Intraclass correlation coefficient (ICC), Bland-Altman, linear regression, mean bias (MB), and proportional bias analyses were quantified and assessed. Threshold measurements, TRV, and blind spot location accuracy were compared with those of the HFA.
Main Outcome Measures:
Pointwise threshold sensitivity, sectoral mean sensitivity (MS), mean deviation (MD), pattern standard deviation (PSD), TRV, blind spot location, average test time were computed, and data were correlated.
Results:
The mean time required to perform a field test with the AVA was 7.08 ± 1.55 minutes and with HFA was 6.26 ± 0.54 minutes (P = 0.228). The MS difference between AVA and HFA was -2.2 ± 2.3 dB in healthy participants (P < 0.001) and -2.6 ± 3.5 dB in participants with glaucoma (P < 0.001). The correlation coefficients for pointwise threshold values were moderately to strongly correlated for both the devices (r = 0.68-0.89). For MS, the overall ICC value was 0.893 (P < 0.001) with MB of 2.48 dB and a limits of agreement (LOA) of 10.90 (range, 7.93 to -2.97). For TRV, response variability decreased with an increase in sensitivity and increased with eccentricity. Blind spot location was accurate, and global indices of testing methods correlated well.
Conclusions:
The AVA effectively captures threshold values for each point in the visual field. Adequate functional correlation suggests substantial equivalence between the AVA (ESA) and HFA (SITA Standard), implying that AVA may allow accurate assessment of visual field.
