Purchase this article with an account.
Muneyoshi Kaneko, Shigeki Machida, Takeshi Sugawara, Koji Otaka, Daijiro Kurosaka; Alternation of Photopic Negative Response of Multifocal Electroretinogram in Patients with Optic Nerve Atrophy. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5700.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We previously demonstrated that the photopic negative responses (PhNRs) in patients with optic nerve atrophy (ONA) showed deterioration not only in the full-field cone electroretinograms (ERGs) but also in focal macular ERGs (Gotoh et al., 2004; Tamada et al., 2009), indicating that the neural activity of retinal ganglion cells (RGCs) contributes to the shape of the PhNR in both full-field and focal ERGs. The present study aimed to clarify the contribution of RGC activity to the shape of the PhNR in the multifocal ERG (mfERG).
Four patients with unilateral ONA (20-59 years old) were included. All patients had central scotoma in either eye as determined by visual field testing. We lowered the stimulus frequency to 6.25 Hz. Low- and high-cut filters of the amplifier were set at 3 and 30 Hz, respectively, to record slow waves. The mfERG was elicited by a 15° circular stimulus centered on the fovea (Center, C). The mfERG was also elicited by a quarter of an annulus placed around the macula (Temporal Superior, TS; Temporal Inferior, TI; Nasal Superior, NS; Nasal Inferior, NI). The diameter of the inner border of the annulus was 15° and that of the outer border was 30°. We measured the nerve fiber layer thickness (RNFLT) around the optic nerve head using optical coherence tomography.
MfERG waveforms obtained using a low-frequency stimulus mimicked those of full-field cone and focal macular ERGs, which consisted first of negative- and positive-going waves (N1 and P1) followed by a slow negative-going wave (N2: corresponding to the PhNR). There were no significant differences between the affected and unaffected eyes in N1 and P1 amplitudes in any areas. All patients showed reduced amplitudes of N2 in the C area of the affected eyes compared to those of the unaffected eyes. A significant difference was found in the N2/N1 and N2/P1 amplitude ratios in this area (P<0.05). However, in other stimulus areas, including TS, TI, NS and NI, there were no differences for any components of the mfERG. RNFLT was thinner in the temporal areas of the optic nerve head in the affected eyes than in the unaffected control eyes.
The present results suggest that the N2 (PhNR) of the mfERG obtained using low-frequency stimuli reflects RGC activity in patients with ONA. In the future, the mfERG could facilitate regional assessment of RGC function.
This PDF is available to Subscribers Only