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A. Berezovsky, A. G. Fernandes, J. M. Pereira, P. Y. Sacai, S. E. S. Watanabe, S. R. Salomao; Comparison of Ergs Recorded With Skin, Microfiber and Contact Lens Electrodes in Patients With Retinal Dystrophy. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4521.
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© ARVO (1962-2015); The Authors (2016-present)
Compare electroretinogram (ERG) responses to full-field stimuli recorded with skin, microfiber and contact lens electrodes in patients with retinal dystrophy.
ERG responses (ISCEV standard full-field protocol) were recorded from both eyes in 15 patients with retinal dystrophy using three types of electrodes in three consecutive visits in the same week. Subjects were aged 12-53 years (31.7±14 years, 9 males). ERG outcomes were analyzed by Kruskal-Wallis test and multiple comparison procedures by Dunnett’s method. Retinal dystrophy type was classified on the basis of standard clinical criteria as retinitis pigmentosa, cone dystrophy and Stargardt’s disease. ERG responses were compared with normative data from our own lab.
The specific type of ERG abnormality was consistent with clinical findings in all tested patients. ERG amplitudes recorded with skin electrode were statistically smaller for all ISCEV responses. Scotopic ERG amplitude median values using skin, microfiber and contact lens electrode were, respectively, 37.2µV; 103.4µV and 203.7µV. Under photopic conditions skin, microfiber and contact lens electrode median amplitudes were, respectively, 11.6µV; 19.3µV and 43.1µV. The waveform morphology of rod and cone skin electrode responses was similar to those obtained with either contact lens or microfiber electrodes. Contact lens electrodes provided ERG amplitudes 4 to 5 times larger than skin electrodes for all responses. Microfiber amplitude was smaller than contact lens electrode for scotopic combined cone-rod stimulation and for cone and flicker response. Implicit time was statistically faster for rod (p=0.007) and maximal (p=0.035) response for skin recorded. Scotopic ERG b-wave implicit time median values using skin, microfiber and contact lens electrode were, respectively 31.5ms; 35.0ms and 38.5ms. Under photopic conditions skin, microfiber and contact lens electrode median values b-wave implicit time were respectively 25ms; 26.5ms and 28.2ms. No statistical differences were found for implicit time between microfiber and contact lens electrodes for all ISCEV responses.
ERGs were successfully recorded using these three types of electrodes in patients with retinal dystrophies. Despite of providing lower amplitude responses, skin electrodes might be a feasible choice for ERG recordings especially in children, patients with abnormalities in the ocular surface and uncooperative/sensitive patients. Separate normative values need to be collected for each type of electrode to accurately assess retinal function.
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