Abstract
Purpose::
Many parameters take direct influence on the results of conducting retinal responses with the multifocal electroretinogram. Two important of them are luminance and contrast of the stimulus array. This study targets to assess the effects of different levels of stimulus luminance on mfERG responses.
Methods::
Multifocal electroretinograms were obtained from 15 healthy subjects aged 16 to 41 years (Median 23,0). Luminance of the stimulating hexagons were either 100, 200, 300, 400, 500 or 600 cd/m². Contrast resulted from 96.08 (100 cd/m²) to 99.34 (600 cd/m²).
Results::
Implicit times of N1 and P1 decreased with increasing luminance of the stimulating hexagons. Large differences were found when recordings with 100 cd/m² and higher luminance levels with 400, 500 and 600 cd/m² were compared to each other. Response amplitudes of N1 and P1 both increased from 100 to 300 cd/m² significantly, but reaching a quite stable plateau at 300 cd/m² with no significant changes in comparision to higher luminance levels.
Conclusions::
Both implicit times and response amplitudes depend directly on the chosen stimulus luminance, particularly evident when lower luminance levels were used. Standardised mferg setups, accurate calibration and verification of constant luminance levels at the beginning of each recording are important for reproducible and comprehensible results, particularly when follow-up recordings have to be compared to exclude a progression of a disease.
Keywords: electroretinography: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)