The influence of luminance on the multifocal ERG

To assess the efficacy of high luminance in increasing the amplitude of the multifocal electroretinogram (mfERG). We examined 5 male and 5 female volunteers in the age of 22-52 years (median 28 years). Three different stimulus luminance levels were applied: the bright areas of the stimulus pattern were set to 150, 300 and 500 cd/m(2). We recorded the potentials via DTL electrodes using the VERIS Science 4.4 system with 61 hexagons, pupils were dilated. Analysis was based on the 5 ring averages.

Across all hexagons and subjects, the response density (approximately amplitude) rose by 20% when increasing the luminance by a factor of 3.3. The peak times decreased slightly with higher luminance, by less then 1.5 ms.

Combining the present results with those from two previous studies, the gain (= relative amplitude increase for relative luminance increase) is close to 0.4 over a range of 56-700 cd/m(2). The stimulus luminance range suggested in the mfERG guidelines seems well chosen.