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Comparison of guinea pig electroretinograms measured with bipolar corneal and unipolar intravitreal electrodes

  • Weisinger, Harrison S.
  • Sinclair, Andrew J.1
  • Vingrys, Algis J.2
  • 1 University of Melbourne, Department of Optometry and Vision Sciences, Parkville, 3052, Victoria, Australia , Victoria
  • 2 Royal Melbourne Institute of Technology University, Department of Food Science, Melbourne, Victoria, 3001, Australia , Melbourne
Published Article
Documenta Ophthalmologica
Kluwer Academic Publishers
DOI: 10.1023/A:1001780529354
Springer Nature


This study considers the precision and accuracy of bipolar corneal electrodes compared with unipolar intravitreal methods in collecting electroretinographic (ERG) recordings from a small animal. Flash ERGs were obtained from 9 adult guinea pigs on three occasions. Corneal bipolar (Burian-Allen) electrodes were used to collect data on the first two occasions whereas unipolar intravitreal electrodes were used on the last. We identified the a-wave, b-wave, oscillatory potentials, PIII and PII responses. Intensity-response functions were fit using a Naka-Rushton relationship with a bootstrap estimating the 95% confidence limits. Discrepancy analysis was applied to determine the coefficient of agreement. We found significantly larger amplitudes with unipolar intravitreal electrodes (ANOVA; a-wave, p<0.002; b-wave, p<0.001; Oscillatory potentials (OPs), p<0.005) especially at high intensities. Implicit times showed little differences between electrodes for the a-wave, significantly faster (p<0.03) b-waves at some intensities, and significantly slower (p<0.005) OP implicit times across all intensities. The PIII amplitude (log μV), sensitivity and timing were not significantly different (p>0.05) if expressed in logarithmic units but PII amplitude (log μV) was significantly smaller with corneal electrodes. We suggest that a conversion factor (x1.35) should be applied to data collected with bipolar corneal electrodes to estimate the amplitudes of the modelled parameters accurately. The corneal electrode gave a precision of ± 39 μV which yields a statistical power of 0.90 for a sample size of 7 subjects. We conclude that bipolar corneal electrodes provide smaller electroretinogram amplitudes due to their location and reduced span of the retinal generators.

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