Optometry Research Today is a free monthly online journal that collates and summarizes the latest research about Optometry, including details on myopia, optometric practice, therapy. | ||||||||
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Slow flash multifocal electroretinogram in myopia.Chen JC, Brown B, Schmid KL School of Optometry, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. jc.chen@qut.edu.ca 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 (2(13)-1). The stimulation sequence was slowed by inserting three dark frames such that each step in the m-sequence was four frames long (53.3ms). 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 (F(1,25)=8.818, p=0.007; F(1,25)=6.723, p=0.017). There were no significant differences in N1 amplitude or implicit time between the groups (F(1,25)=1.506, p=0.233; F(1,25)=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. Published 3 July 2006 in Vision Res, 46(18): 2869-76.
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