Performance of the DTL electrode compared to the jet contact lens electrode in clinical testing

To compare the recording characteristics of the DTL fiber and Jet contact lens electrodes, ERG responses were recorded from 20 normal subjects using the ISCEV standard clinical protocol. In each subject, the DTL electrode was placed in the right eye and the Jet contact lens in the left eye after 30 min of dark-adaptation. After presenting standard dark- and light-adapted stimuli, each response was analyzed for a- and b-wave amplitude and implicit time. Each subject was then asked to rate the comfort of each electrode. Responses recorded with the DTL are larger and faster for the dark-adapted dim white and red flashes. In contrast, the Jet electrode records larger responses for the dark-adapted standard flash and light-adapted flashes. Of these differences, only the standard flash is statistically significant. However, overall the DTL electrode has greater variability than the Jet electrode across all recordings. The DTL and Jet electrodes cannot be used interchangeably as demonstrated by a Bland and Altman analysis of agreement. Thus, separate normative values need to be collected for each type of electrode to accurately assess retinal function. Based on the comfort assessment of the two electrodes, the subjects preferred the DTL electrode over the Jet electrode. Due to the superior comfort level of the DTL and its similarities to the Jet contact lens electrode in ERG recordings, the DTL electrode appears to be a good alternative to the Jet electrode in routine clinical testing when used with the appropriate normative values.