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Muneyoshi Kaneko, Shigeki Machida, Yuya Hoshi, Daijiro Kurosaka; Alteration of Photopic Negative Response of Multifocal Electroretinogram elicited by seven hexagons in Patients with Glaucoma. Invest. Ophthalmol. Vis. Sci. 2014;55(13):337.
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© ARVO (1962-2015); The Authors (2016-present)
We previously reported that patients with glaucomatous optic neuropathy (GON) have reduced photopic negative responses (PhNRs) of full-field light-adapted flash ERG and focal ERG as well as 5-element multifocal ERG (mfERG). Here we determine whether data on retinal localization of glaucomatous changes can be obtained with more detail by increasing the number of elements in mfERG recording from 5 used in a previous study to 7.
Eight patients with GON, all with glaucomatous visual field defect on static quantitative perimetry, were observed with 7-hexagon mfERG (center, C; temporal superior, TS; temporal inferior, TI; nasal superior, NS; nasal inferior, NI; temporal, T; nasal, N). The stimulus frequency was reduced to 6.25 Hz and the low- and high-cut filters set to 3 and 30 Hz, respectively, to record the slow waveforms.
The low-frequency stimuli elicited mfERG waveforms closely resembling those seen with full-field light-adapted flash ERG and focal ERG, consisting of an initial negative wave and a positive wave (N1 and P1), followed by a slow negative wave (N2, corresponding to the PhNR). We found no significant differences between the normal control and glaucomatous eyes in N1 and P1 response densities across all regions. Meanwhile, significant differences were noted in N2 response density in the TI, C, and T regions and in N2/N1 and N2/P1 response density ratios in the C and T regions (P < 0.05). No significant differences, however, were noted for any mfERG components in other regions, including TS, NS, NI, and N.
We previously reported that the 5-element mfERG responses showed significant reductions of the N2 response density and response density ratios of the N2/N1 and N2/P1 in the C region. In the preset study, the 7-element mfERG responses showed significant reductions of all these ERG parameters in both the C and T regions, suggesting that the temporal regions are also susceptible to glaucomatous damage. The results also indicate that increasing the number of elements in mfERG recording can potentially generate more detailed data on retinal localization of glaucomatous changes.
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