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. 2022 Nov 11:16:3733-3740.
doi: 10.2147/OPTH.S382207. eCollection 2022.

Effect of Pupil Size on Fixed-Luminance Flicker Full-Field Electroretinogram Magnitude

Azadeh Mobasserian #  1 , Moosa Zaidi #  1 , Sohail Halim  1   2 , Jaclyn Joyce Hwang  1 , Jonathan Regenold  1 , Amir Akhavanrezayat  1 , Irmak Karaca  1   3 , Hassan Khojasteh Jafari  1 , Negin Yavari  1 , Wataru Matsumiya  1   4 , Cigdem Yasar  1   5 , Ngoc Tuong Trong Than  1 , Gunay Uludag  1 , Diana Do  1 , Hashem Ghoraba  1 , Quan Dong Nguyen  1
Affiliations

Effect of Pupil Size on Fixed-Luminance Flicker Full-Field Electroretinogram Magnitude

Azadeh Mobasserian et al. Clin Ophthalmol. .

Abstract

Purpose: Diopsys® NOVA fixed-luminance flicker full-field electroretinogram (ffERG) device is a potential adjunct to conventional flicker ffERG testing for assessing cone cell function. Magnitude of measured electrical response is known to vary with pupil size in conventional ffERG testing. The index study characterizes the relationship between magnitude of measured electrical activity and pupil size, both pupil diameter and pupil area, for this device.

Methods: Seventeen patients (34 eyes) with no known ocular diseases were enrolled in the study. Electrophysiologic function of cone cells was evaluated using fixed-luminance flicker ffERG before and after dilation. Linear regression models, with inter-eye correlations controlled as fixed-effects, were used to characterize the effect of pupil dilation on the magnitude of the measured responses.

Results: Mean age of study patients was 33.5 (standard deviation 7.4 years), and 35.3% of the subjects were female. Mean value of electrical response magnitude was 10.07±2.79µV before dilation and 15.30±4.08µV after dilation. The correlations of ERG magnitude with pupil diameter and with pupil area were not significant for either dilated or undilated eyes considered separately but were highly significant (p<0.001) for dilated and undilated eyes considered in aggregate. ERG magnitude tended to increase by 1.08 µV for every 1 mm increase in pupillary diameter.

Conclusion: An increase in pupil size, both pupil diameter and pupil area, is significantly associated with an increase in flicker ffERG magnitude recorded by the Diopsys device, suggesting that pupil size should be measured and considered when making clinical judgments based on the flicker ffERGs recorded by the device, and that pupil size-specific reference ranges could improve the clinical utility of the device.

Keywords: Diopsys; ERG; electroretinogram; flicker ERG; magnitude; pupil.

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Conflict of interest statement

The authors report no conflicts of interest in this work.

Figures

Figure 1
Figure 1
Comparison of the ERG magnitudes recorded in eyes before (blue) and after (orange) dilation. Means (±SDs) are labeled for each group.
Figure 2
Figure 2
Association between pupil diameter (mm) and ERG magnitude (µV) in eyes prior to dilation (A) and after dilation (B). The results of a fixed-effect linear regression model, with a per-subject fixed effect, are shown for both. These results include the pupil diameter coefficient and intercept (equation and red line), the p-value of the coefficient, and the adjusted R2 value of the model.
Figure 3
Figure 3
Association between pupil diameter (mm) and ERG magnitude (µV) with eyes before (blue) and after (orange) dilation considered together. The results of a fixed-effect linear regression model, with either a per-subject fixed effect (A) or a per-eye fixed effect (B) are shown. These results include the pupil diameter coefficient and intercept (equation and red line), the p-value of the coefficient, and the adjusted R2 value of the model.
Figure 4
Figure 4
Association between pupil area (mm2) and ERG magnitude (µV) with eyes before (blue) and after (orange) dilation considered together. The results of a fixed-effect linear regression model, with either a per-subject fixed effect (A) or a per-eye fixed effect (B) are shown. These results include the pupil area coefficient and intercept (equation and red line), the p-value of the coefficient, and the adjusted R2 value of the model.
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