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M. T. Barboni, G. Pangeni, D. F. Ventura, J. Kremers; Phase Changes in the Chromaticity and Luminance Driven Flicker Electroretinograms (ERGs) of Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3264.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the chromatic and luminance channels in glaucoma patients by measuring heterochromatic flicker ERGs and to compare the responses between normal, perimetric and preperimetric glaucoma eyes.
Flicker ERGs were recorded with a DTL fiber electrode from one dilated eye of 32 patients (20 perimetric, 12 preperimetric, mean age = 61 ± 11 years old; 15 males and 17 females) from the "Erlangen Glaucoma Registry" and the control group comprised 20 healthy volunteers (mean age = 41 ± 10 years old; 12 males and 8 females). Red and green LEDs were modulated in counterphase on a Ganzfeld stimulator with a mean luminance of each LED of 100 cd/m² and a yellow mean chromaticity. The flicker ERGs were previously found to reflect red-green chromatic activity at 12 Hz temporal frequency and of the luminance channel at 36 Hz. The recordings were Fourier analyzed and the responses were defined as amplitudes (in microvolts) and phases (in degrees) of the first and second harmonic components.
There was no amplitude difference between glaucoma patients and controls in the chromatic and luminance channels. The phases of the first and second harmonic components showed response delays in the perimetric patients in both chromatic and luminance channels. In addition, the preperimetric patients displayed phase changes at 36 Hz (luminance channel).
These preliminary data suggest that there are phase changes in both chromatic and luminance channels, but there seems to be an earlier phase change in the luminance channel (M pathway). These results may be important to establish retinal changes at a stage prior to perimetrically detectable visual losses.
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