A prospective evaluation of the repeatability and reliability of new steady-state pattern electroretinogram parameters

Purpose: The purpose of this study was to determine the repeatability and reproducibility of a new Pattern Electroretinography (PERG) device in healthy subjects. Methods: A total of 40 eyes of 20 healthy subjects (45.6 +/- 6.8 y, 70% female) were enrolled in this prospective study. Steady-state PERG were recorded using the Diopsys NOVA (Diopsys Inc., NJ) to obtain the Magnitude, MagnitudeD, MagnitudeD/Magnitude Ratio, and Signal to Noise Ratio. Subjects underwent 2 "contrast sensitivity" protocols with the same electrodes and 2 after changing electrodes, by a single examiner. Eyes were stimulated separately using high and low contrast patterns. The same examination was repeated by a different operator following the same protocol 6 months after the baseline measures. Repeatability and reproducibility of the readings were calculated using intraclass correlation coefficient (ICC). A Bland-Altman plot was used to analyze the agreement between measures. Results: ICC of Magnitude, MagnitudeD, MagnitudeD/Magnitude ratio, and SNR were 0.87, 0.81, 0.36, and 0.81, respectively between measures taken with the same electrodes (repeatability). After changing electrodes, ICC of the Magnitude, MagD, MagD/Mag ratio, and SNR were 0.79, 0.85, 0.51, and 0.83, respectively during the same session as baseline measures, and 0.87, 0.85, 0.40, and 0.76 when repeated after 6 months (reproducibility). The variability of MagD/Mag ratio increased with successive test repetitions. Conclusions: Mag, MagD, and SNR were repeatable and reproducible, whereas the MagD/Mag ratio was less repeatable and reproducible. These results suggest that the former parameters are sufficiently reliable to be used in clinical practice