Materials and Methods: PERG recordings of 22 right eyes of 22 subjects were recorded three days apart. PERG recordings of the 64 eyes of 32 subjects were made for assessing inter-individual and inter-ocular variability. Inter-ocular variability was determined by the difference between right and left eye recordings and inter-individual variability was determined by using right eye recordings. Variability calculations were made with two different methods, ‘variability percentile’ and ‘coefficient of variability’. Variability percentile is the ratio of the absolute difference between two recordings to the first recording. Coefficient of variability is the ratio of standart deviation to mean.

Results: Regarding all evaluations, the highest variability ratios were determined for P50 amplitudes and the lowest ratios were determined for P50 latencies. While inter-session, inter-ocular and inter-individual variabilities for P50 amplitude were 37.1%, 39.2%and 28.2%in terms of ‘coefficient of variability’, these ratios were 11.0%, 13.6%and 6.4%for P50 latency.

Conclusion: The variability ratios that we found in this study necessitates regarding normal variability ranges of pattern electroretinogram, both in routine clinical applications and in electrophysiologic studies. Keywords : Pattern electroretinogram, reproducibility, variability