Figure 5.

Reduction in measurement error (between-test measurement variability) following home monitoring. (A) Estimated rate of change (in dB per half-year), as increasing numbers of Eyecatcher tests are added to a single (randomly selected) pair of Humphrey Field Analyzer (HFA) pre-/post-test results, made 6 months apart. As described in the main text, the true change in sensitivity is assumed to be 0, so any nonzero values represent measurement error. Ten of 40 eyes are shown here (same eyes as Figure 4). Results from the remaining 30 eyes are given in Supplemental Figures 7-9. Numbers above tests show mean absolute error (MAE), which would ideally be zero. (B) Mean (±95% confidence interval [CI₉₅]) MAE, averaged across all 40 eyes, as a function of N home-monitoring assessments (months). Filled circles correspond to the scenario in (A) and show how measurement error decreased as Eyecatcher data were added to a random pair of HFA_pre/HFA_post assessments (ie, “ancillary home-monitoring scenario”). Unfilled markers show measurement error if Eyecatcher data were considered in isolation, without any HFA data (ie, “exclusive home-monitoring scenario”). Error bars denote 95% confidence intervals, derived using bootstrapping (bias-corrected accelerated method, N = 20,000). The shaded region highlights the CI₉₅ (1.7-2.3 dB) given only a single random pair of HFA assessments (ie, the current clinical reality after 2 appointments). (C) Histograms showing the distributions of all 880 rate-of-change slopes (22 visual field locations × 2 eyes × 20 participants). Vertical dashed lines show the 5th and 95th percentiles.