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Y. Shimada; Clinical Usefulness of 18.75 Hz–Multifocal Electroretinogram Compared With 75 Hz . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4554.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Many recent studies have used 18.75 Hz–mfERGs or even slower base rates because of the richness of the oscillatory components and resemblance to single flash ERGs. The purpose of this study was to determine the clinical usefulness of a slow base rate (18.75 Hz) of stimulation to elicit multifocal electroretinograms (mfERGs) compared with the standard 75 Hz base rate. Methods: Six control subjects and 8 cases with different retinal diseases including macular hole, diabetic retinopathy, and AZOOR had mfERG recordings with both 18.75 Hz and 75 Hz base rate of stimulation. The stimulus consisted of 37 hexagons with a stimulus intensity of 2.67 cds/m2 and a net recording time of 3'38". Results: The mfERGs elicited by 18.75 Hz and 75 Hz demonstrated known retinal lesions, e.g., the markedly reduced amplitudes in the case of AZOOR. The peak–to–peak amplitude of the 18.75 Hz–mfERG (bandpass 10–300 Hz) was 148% and 205% (100–300 Hz) of that at 75 Hz. The noise level calculated as RMS of a vacant channel was also 198% higher. The higher order kernels of the 18.75 Hz–mfERGs were smaller and were not large enough to analyze local changes. The effect of stray light as detected responses from a case with an enlarged optic disc was greater. Conclusions: Compared with the 75 Hz–mfERGs, the 18.75 Hz–mfERG has important disadvantages, viz., poorer signal–to–noise ratio, more stray light effects, and reduced higher order kernels making detailed analyses more difficult.
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