Evidence-based Criteria for Assessment of Visual Field Reliability

Abstract

Purpose: Assess the impact of false-positives (FP), false-negatives (FN), fixation losses (FL), and test duration (TD) on visual field (VF) reliability at different stages of glaucoma severity.

Design: Retrospective.

Participants: A total of 10 262 VFs from 1538 eyes of 909 subjects with suspect or manifest glaucoma and ≥5 VF examinations.

Methods: Predicted mean deviation (MD) was calculated with multilevel modeling of longitudinal data. Differences between predicted and observed MD (ΔMD) were calculated as a reliability measure. The impact of FP, FN, FL, and TD on ΔMD was assessed using multilevel modeling.

Main outcome measures: ΔMD associated with a 10% increment in FP, FN, and FL, or a 1-minute increase in TD.

Results: FL had little impact on ΔMD (<0.2 decibels [dB] per 10% abnormal catch trials), and no level of FL produced ≥1 dB of ΔMD at any disease stage. FP yielded greater than expected MD, with a 10% increment in abnormal catch trials associated with a ΔMD = 0.42, 0.73, and 0.66 dB in mild (MD >-6 dB), moderate (-6 ≤MD <-12 dB), and severe (-12 ≤MD ≤-20 dB) disease, respectively, up to 20% abnormal catch trials, and a ΔMD = 1.57, 2.06, and 3.53 dB beyond 20% abnormal catch trials. FNs generally produced observed MDs below expected MDs. FN were minimally impactful up to 20% abnormal catch trials (ΔMD per 10% increment >-0.14 dB at all levels of severity). Beyond 20% abnormal catch trials, each 10% increment in abnormal catch trials was associated with a ΔMD = -1.27, -0.53, and -0.51 dB in mild, moderate, and severe disease, respectively. |ΔMD| ≥1 dB occurred with 22% FP and 26% FN in early, 14% FP and 34% FN in moderate, and 16% FP and 51% FN in severe disease. A 1-minute increment in TD produced ΔMDs between -0.35 and -0.40 dB.

Conclusions: FL have little impact on reliability in patients with established glaucoma. FP, and to a lesser extent FNs and TD, significantly affect reliability. The impact of FP and FN varies with disease severity and over the range of abnormal catch trials. On the basis of our findings, we present evidence-based, severity-specific standards for classifying VF reliability for clinical or research applications.

Conflict of interest statement

Conflict of Interest: No conflict of interest exists for any author

Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Schematic demonstrating how Δ MD (Delta Mean Deviation) was calculated. Predicted MD at each time point was calculated using a regression model whose predictors included the average performance based visual field (VF) tests, time since visual field testing commenced, severity of visual field loss, intraocular pressure (IOP) and surgical history. Δ MD was calculated by subtracting visual field MD measured at the given time point for the given patient from predicted MD at that time point.

Figure 2

Histogram of mean deviation (MD) of the first field of each eye in the visual field database.

Figure 3

Histogram of fixation losses false positives and false negatives in the visual field database

Figure 4

Effect of False positives, false negative and fixation losses on delta mean deviation (ΔMD).