Abstract
Purpose :
Standard automated perimetry (SAP) is a method for estimating the sensitivity of the retina at different locations. However, at locations where sensitivity has been reduced due to glaucoma, the frequency-of-seeing curve has a shallow slope. This means that it is possible to use the fraction of stimuli seen for a fixed-contrast, suprathreshold stimulus as an alternative measure of visual sensitivity at these locations (Backus et al, ARVO 2020; Greenfield et al, Ophth Sci 2022). To evaluate the effectiveness of this fixed-contrast testing procedure for measuring loss, we analyzed data from a cross-sectional study of patients with glaucoma who performed visual field tests at home.
Methods :
Data of Chia et al (ARVO 2022) were reanalyzed. 21 patients with glaucoma from the UCSF Glaucoma Clinic (mean age, 62.2 years) performed 10 visual field tests at home using a novel testing procedure on mobile virtual reality headsets (Vivid Vision Perimetry, VVP, San Francisco, CA). The stimulus was black-on-white, 0.43 deg in diameter, blurred, and 0.30 s in duration. Each eye was tested at 54 retinal locations using the Humphrey Field Analyzer (HFA) 24-2 test pattern, with 4 stimuli presented at each location. Fraction-seen was correlated with HFA sensitivity. Test-retest variability for VVP was estimated from the SE across tests and for HFA it was estimated to be 1 dB (Chauhan et al, IOVS 2008). Spearman correlation compared VVP fraction seen to HFA mean deviation (MD) across eyes.
Results :
20 patients completed the home testing schedule, yielding 35 eyes for analysis. 40 stimuli were presented at each location over 10 sessions. Fraction-seen varied nearly linearly with HFA sensitivity from 5 to 25 dB, both within and across eyes. Comparing fixed-contrast to HFA, test-retest variability was lower by a factor of 4 where sensitivity was between 10 and 20 dB, and by a factor of 2.5 for the entire field, in this patient group. For the 16 eyes that had MD of -6 dB or worse, fraction-seen and mean sensitivity correlated very well (r = 0.88, 95% CI [0.66, 0.99], P < 0.001).
Conclusions :
VF testing with a suprathreshold, fixed-intensity stimulus is a valid approach for monitoring field loss that is roughly as efficient as the varied-contrast approach. If patients find fixed-contrast tests easier to perform, this test may be used to monitor visual field status at home.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.