Fatigue effects in automated perimetry

Abstract

The influence of fatigue and related factors on automated perimetric testing was evaluated in both eyes of sixteen normal observers and sixteen patients with early-to-moderate visual field loss using a Digilab 750 automated perimeter and a customized test procedure. False positive rate, false negative rate, and detection sensitivity at 5,10,15, and 20 degrees eccentricity were measured in 1.5-rain intervals throughout a 21-min visual field examination. Half of the normal observers and patients with visual field loss were given a briefrest(1.5-min) midway through each visual field exam to determine whether this would reduce fatigue effects. Our findings revealed that patients displayed considerably higher average false positive and false negative rates than normal observers. However, neither the patients nor normal observers demonstrated any consistent changes in false positive rate or false negative rate as a function of testing duration. In contrast, both normal observers and patients showed an average decrease in sensitivity as a function of increasing test duration with the magnitude of the time-dependent sensitivity loss becoming greater with increasing stimulus eccentricity. Patients demonstrated a larger time-dependent sensitivity loss than normal observers, averaging ~4dB at 20 degrees eccentricity. The introduction of a brief pause midway through the test procedure appeared to reduce the time-dependent sensitivity loss for the second half of the test procedure, especially for greater eccentricities.

Psychophysics, reliability, and norm values for temporal contrast sensitivity implemented on the two alternative forced choice C-Quant device

“…35 Several (flicker) perimetry studies show systematical variation between measurements and it is suggested that these are learning and fatigue effects. [36][37][38][39] However, for single frequency temporal contrast measurements, it is mentioned that fatigue effects are small, due to the relative simplicity and short duration (a few minutes) of the measurement. 12 In addition, the 2AFC method applied in this study shows no learning effects, i.e., there is no systematical difference between subsequent measurements, as can be seen in Fig.…”

Comparison of Diagnostic Ability between a Fast Strategy, Tendency-Oriented Perimetry, and the Standard Bracketing Strategy

“…Some differences between fast and BR strategies have been described. Short strategies show lower mean defect (MD) results, since they are less influenced by the ‘fatigue effect’, which has its origins in the neuronal exhaustion that happens after being exposed to the uniform light of the perimeter for a long time [11,12,13]. Recent studies suggest a better reproducibility of short strategies, which may facilitate the detection of visual field changes [14, 15].…”

Comparison of Glaucomatous Visual Field Defects Using Standard Full Threshold and Swedish Interactive Threshold Algorithms

“…[4][5][6][7][8][9] However, the standard FT method for measuring the visual field is time-consuming for patients and is subject to fatigue effect, which has been shown to result in poorer results. [10][11][12] This effect is more pronounced in patients with glaucoma. 11,13 The Swedish interactive threshold algorithm (SITA) is a new computer program that was developed for the Field Analyzer II (Humphrey Systems, Dublin, Calif) that reduces test-taking time.…”