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Shresta Patangay, Zahra Derafshi, Jason C Park, Elham Ghahari, Thasarat S Vajaranant, J Jason McAnany, John R Hetling; Reversal rate dependence and nasal-temporal field differences in high-luminance peripheral pattern electroretinogram (ppERG) responses in healthy human eyes.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5765.
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© ARVO (1962-2015); The Authors (2016-present)
A high-luminance pattern stimulus source that probes the peripheral retina was previously described; in that study, the peripheral pattern electroretinogram (ppERG) demonstrated greater sensitivity to glaucomatous damage than conventional pERG (ISCEV protocol), motivating further characterization of the ppERG response. Here, the effect of reversal rate is examined, and nasal-temporal field differences are described, for ppERG responses in healthy eyes.
Responses were recorded from six normally-sighted subjects, ages 19-48 yrs. A three-dimensional pattern stimulus source filled the peripheral visual field, extending from 50o – 80o of visual angle in all directions. Mean luminance of ON-checks was 1670 ph cd m-2. Transient responses were recorded at 2.3, 4.6 and 9.2 reversals per second (RPS) using 10o checks. To evaluate temporal and nasal field responses (at 4.6 RPS), a 4x4 check pattern was presented to each field between 29o and 70o of visual angle, such that the nasal-field pattern was not obstructed by the bridge of the nose. Response waveforms were decomposed into low- and high-frequency components (1-57 Hz, 58-1000 Hz respectively), and peaks were evaluated for amplitude. The low-frequency positive component (P) was measured from baseline; the low-frequency negative component (N) was measured from P.
On average, with increasing reversal rate, P increased (r2 = 0.27) and N decreased (r2 = -0.23). The differences in amplitudes elicited with 2.3 and 9.6 RPS stimuli were significant for P (p = 0.02), and nearly so for N (p = 0.06). Because N was measured from P, the relatively large negative component at 2.3 RPS is masked by this analysis. The high-frequency components were nearly constant for all reversal rates. The mean amplitudes of both P and N were larger in the temporal field, but not significantly (p = 0.07, 0.17, respectively). The high-frequency component amplitudes were nearly constant in both fields.
ISCEV recommends 4 RPS for transient pERG, however a lower reversal rate elicited the largest negative contribution to the ppERG waveform, and should be investigated for correlation with structural measures in glaucoma. The nasal-temporal field differences in P and N amplitudes are consistent with asymmetry in ganglion cell population densities.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Peripheral pattern ERG stimulus source
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