June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
Morning vs. evening variation in peripheral pattern electroretinogram (pPERG) responses in normally-sighted subjects
Author Affiliations & Notes
  • Priyanka Roy
    Bioengineering, University of Illinois at Chicago, Wheaton, Illinois, United States
  • Shresta Patangay
    Bioengineering, University of Illinois at Chicago, Wheaton, Illinois, United States
  • John R Hetling
    Bioengineering, University of Illinois at Chicago, Wheaton, Illinois, United States
    Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
  • Footnotes
    Commercial Relationships   Priyanka Roy, None; Shresta Patangay, US 10,292,580 B2 (P); John Hetling, US 10,292,580 B2 (P)
  • Footnotes
    Support  BrightFocus Foundation Grant
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 2704. doi:
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      Priyanka Roy, Shresta Patangay, John R Hetling; Morning vs. evening variation in peripheral pattern electroretinogram (pPERG) responses in normally-sighted subjects. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2704.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The response of the retina to light can be modulated by melatonin, and melatonin levels vary with time of day. It is, therefore, possible that time of day can be a source of variability in ERG testing. To explore this in effect in peripheral pattern electroretinogram (pPERG) testing, a prospective observational study was performed to compare responses recorded in the morning and evening.

Methods : Monocular pPERG responses were recorded using corneal DTL electrodes, at 4.6 reversals per second, from five normally-sighted subjects, aged 21-52 years, at 8 AM and 8 PM on the same day for each subject. A reversing checkerboard pattern with 5o check size stimulated the peripheral visual field (22o – 50o). Mean ON-luminance was 1670 ph cd m-2. Raw waveforms were separated into low-frequency (LF, 1-50 Hz) and high-frequency (HF, 50-300 Hz) components prior to the evaluation of peak amplitudes and implicit times. The low-frequency components included one positive (P) and one negative (N) peak, the high-frequency components included three positive peaks (F1, F2, F3). The inter- and intra-subject peak amplitude differences (AD) and implicit time differences (ITD) were compared for morning and evening recording sessions.

Results : There were no statistically significant differences in amplitudes or implicit times for any of the peaks (P, N, F1, F2, F3) when comparing the morning and evening responses (p>0.05, paired t-test, n=5). The direction of change (increasing or decreasing amplitudes, longer or shorter implicit times) were not consistent across subjects. The difference between morning and evening responses for a given subject were of similar magnitude to the standard deviation across subjects.

Conclusions : A prior study examining photopic and scotopic flash responses (Lavoie et al., 2010, Doc Ophthalmol) demonstrated small differences in a-wave amplitude and implicit time between morning and evening recording (<10%). The present results, which reveal no time-of-day trend, suggest that pPERG responses are more consistent in the presence of changing melatonin levels, though a larger sample size may reveal a subtle effect.

This is a 2020 ARVO Annual Meeting abstract.

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