Purpose: To investigate the appropriate stimulus luminance for recording the same response as under mydriasis even without mydriasis in the multifocal electroretinogram (mfERG).
Subjects and methods: The subjects were 10 eyes of 10 healthy adults. The mfERG was recorded using pseudo-random stimuli with 37 elements and 75 Hz, and skin-electrodes were used. The mfERG was recorded under non-mydriasis at five different stimulus luminance levels of 200, 500, 1,000, 1,250 and 1,500 cd/m². The retinal response density in each group waveforms (ring 1-4) were compared with the results of the same subjects between under mydriasis and non-mydriasis. Pupil diameter was measured during recording, and the effective retinal illuminance was calculated taking into account the Stiles-Crawford effect (SCE).
Results: The mean pupil diameter during recording without mydriasis was 3.43 mm at 200 cd/m², but decreased to 2.52 mm at 1,500 cd/m². The effective retinal illuminance considering SCE was found to be most similar to the value at mydriasis when a stimulus luminance of 1,000 cd/m² was used without mydriasis. The P1 amplitude was increased with increasing stimulus luminance, reaching a maximum at 1,250 cd/m². The distribution of retinal response amplitude from central to periphery without mydriasis was similar to that of under mydriasis when 500 cd/m² and 1,000 cd/m² stimuli were used.
Conclusions: In the multifocal ERG recording, it was possible to record the same response as under mydriasis even without mydriasis by adjusting the stimulus luminance. The stimulus luminance for recording mfERG without mydriasis was considered appropriate at 1,000 cd/m², which is five times higher than that for mydriasis.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 127: 19-25, 2023.