Table 2 Overview of electrophysiological recording parameters.
From: Effect of nystagmus on VEP-based objective visual acuity estimates
VEP-based VA | |
|---|---|
Recording Device | EP 2000 Evoked potentials system 22 |
Monitor | Monochrome CRT monitor (MDG403, Philips; P45 phosphor; 75 Hz) |
Stimulus | Checkerboard |
Ambient light | Dimly lit room |
Mean luminance | 50 cd/m2; 40% contrast |
Size of stimulus | For BCVA < 0.3 [logMAR]: Six logarithmically equidistant steps from 0.048° to 0.385° For BCVA values > 0.3 [logMAR]: A different sequence of check sizes was utilized: 0.09—0.8° |
Stimulation | steady-state brief onset pattern stimulation (7.5-Hz, 40 ms on, 93 ms off) |
Electrode placement | Laplace montage 23: Gold-cup electrodes at Oz, LO and RO, referenced to FPz (according to the international 10–20 System) |
Recording setting | Signals amplified 100 K times the VEP signals & band pass filtered them (0.3, 70 Hz) |
Artefact rejection | ± 90 µV threshold |
Eye | Monocular recording |
Viewing distance | 114 cm |
Repetitions | A-B-B-A* |
Fixation control | Random digits from 0–9 in the center of the screen & verbal feedback by participants |
Processing | Responses digitally filter with low-pass cutoff of 40 Hz |
Reporting | Decimal VEP-based BCVA 8 |
