Slow flash multifocal electroretinogram in myopia

Purpose The purpose of this study was to investigate the characteristics of retinal function in myopes using a modified multifocal electroretinogram (mfERG) protocol, the slow flash (sf-mfERG) paradigm, which is thought to primarily reflect responses of ON- and OFF-bipolar cells and emphasize the late response components. Methods Twenty-eight subjects (10 emmetropes and 18 myopes) underwent mfERG testing using VERIS 5.1.5X. The sf-mfERG stimulus array consisted of 103-scaled hexagons and flickered according to a pseudorandom binary m-sequence (213-1). The stimulation sequence was slowed by inserting three dark frames such that each step in the m-sequence was four frames long (53.3 ms). The amplitude and implicit time of the major sf-mfERG waveform features (N1, P1, and N2) of the first-order kernel were analysed. Results Myopes had significantly reduced P1 and N2 amplitudes compared to the emmetropes (F1, 25 = 8.818, p = 0.007; F1, 25 = 6.723, p = 0.017). There were no significant differences in N1 amplitude or implicit time between the groups (F1, 25 = 1.506, p = 0.233; F1, 25 = 1.291, p = 0.269). Conclusions Late response components (P1 and N2) of the first-order sf-mfERG responses were preferentially affected in myopia, suggesting possible reduced ON- and OFF-bipolar cell activity. As bipolar cells form the first synapse of the visual system with the photoreceptors to initiate the ON- and OFF-pathways, future investigations of ON- and OFF-systems in myopia are of interest.