Abstract
Purpose: :
To improve the signal-to-noise ratio in multifocal ERG recordings, an as long as possible examination duration (using a long M-sequence or by repeating short M-sequences) is desirable. Purpose of this study was to test, how long an examination duration is sufficient to obtain an acceptable recording quality.
Methods: :
16 healthy subjects underwent repeated multifocal ERG testing (Roland Consult, Wiesbaden, Germany) with a resolution of 61 hexagons using short M-sequences with 512 steps of 47 s duration for stimulation. The retest-repeatability of examinations with 1 up to 8 averages of 47-s-sequences were calculated using coefficients of variation.
Results: :
The retest-repeatability improved with increasing number of averages expressed by decreasing coefficients of variation from 1 up to 8 averages: 0.36, 0.22, 0.2, 0.18, 0.14, 0.15, 0.13 and 0.13. Whereas the difference of the repeatability between 1, 2, 3 and 4 averages on the one hand and 8 averages on the other were significant, no significant difference could be noticed after the fifth average compared to 8 averages.
Conclusions: :
Our study shows that in multifocal ERG recordings using short M-sequences with a resolution of 61 hexagons more than 5 averages of 47-s-sequences do not improve the repeatability of the results. Thereby examination time and exposure of the patient can be limited by restricting to 5 averages without losing recording quality.
Keywords: electroretinography: clinical