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S. Viswanathan, A. W. Van Alstine, W. H. Swanson, L. J. Frishman, J. A. Grogg; Multifocal Photopic Negative Responses (mfPhNR) in Open Angle Glaucoma (OAG). Invest. Ophthalmol. Vis. Sci. 2010;51(13):3262.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether mfPhR of the slow sequence multifocal electroretinogram is reduced in OAG patients.
mfERGs (0.1-300Hz) were recorded from 25 OAG patients (51-86yrs) and 61 control subjects (22-79yrs) using the VERIS system. Stimuli consisted of 7 unstretched 12 deg hexagons presented with 30 frames per m-step, m-sequence exponent of 9 and flash strength 9.9 cd-s/m2. Perimetric testing was conducted using 24-2 test pattern, stimulus size III and SITA Standard algorithm with a Humphrey system. mfPhNR amplitude was studied as a function of perimetric sensitivity from the same test locations (dB values at four locations within each hexagon were converted to linear values and averaged). Retinal nerve fiber layer thickness (NFLT) for a ring around the optic nerve head was measured using spectral domain ocular coherence tomography (OCT) from Heidelberg. Averaged mfPhNR amplitude from the central and nasal retinal locations were compared to the NFLT of temporal segment around the disc. Bland-Altman analyses were used to assess dependence of test-retest versus mean of two repeat measures.
mfPhNR amplitudes measured at fixed times around 75 ms from OAG patients were significantly reduced at all test locations (p<0.0001), a- and b- wave amplitudes were normal (p>0.06). mfPhNR amplitude from control subjects and OAG patients showed low but significant correlations with perimetric sensitivity (r=0.44, p<0.001) as well as NFLT (r=0.45, p<0.0001) similar to the correlation between perimetric sensitivity and NFLT (r=0.33, p=0.002). The test-retest differences in mfPhNR amplitude and perimetric sensitivities were not correlated with mean amplitude or sensitivity for any of the test groups (r≤0.22,p≥0.09). The test-retest variabilities of the mfPhNR amplitude were similar for most test locations except the superior field where the variability appeared to be greater in OAG patients (F > 1.76, p<0.02). The test-retest variability of perimetric sensitivity was consistently lower in OAG patients (F>1.83, p<0.02).
mfPhNR was selectively reduced in OAG patients and its test-retest variability was quite similar to that of control eyes. mfPhNR holds promise as an objective test for simultaneous assessment of ganglion cell function from multiple retinal locations.
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