Inter-Session Reproducibility and Inter-Subject Variability of Pattern Visually Evoked Potentials: The Effect of Check Sizes on Reproducibility

Purpose: The aim of this study is to describe inter-session reproducibility and inter-subject variability of pattern visually evoked potentials and to assess the effect of check sizes on reproducibility.Materials and methods: Thirty-nine right eyes of 39 subjects with no known systemic and ocular disease were obtained in this study. PVEP recordings of these subjects were made one week after another. First, normative values and 95% confidence intervals belonging to the sessions were assessed. Inter-subject variabilities were assessed by means of minimum and maximum limits of 95% confidence interval belonging to the first session. Normative variability ranges and 95% confidence interval for these ranges belonging to the PVEP parameters were calculated by having absolute differences between sessions.Results: While the inter-subject variability of 100 latency was between %20-30, the inter-session variability of P100 amplitude was % 761 for 7'. Regarding inter-session variability, the highest variability percentiles were found for N135 amplitude (20%+/- 20%, for 2 degrees). The lowest variability percentiles were found for N751atencies (3.7%+/- 3.7%, for 2 degrees) and P100 latencies (4.8%+/- 4.7%, for 20). Mean P100 amplitude variability percentile for 2 degrees was 19%+/- 0%.Conclusion: Inter-session reproducibility of PVEP, especially for P100 amplitudes, was found low. Inter-subject variabilities for P100 amplitude are high. It was found that check sizes have no significant effects on inter-session reproducibility. We think that this high variability ranges should not be forgotten in clinical studies in which PVEP will be used as a reference test.