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Azadeh Mobasserian, Muhammad Sohail Halim, Jacklyn Joyce Hwang, Jonathan Regenold, Amir Akhavanrezayat, Hashem Ghoraba, Wataru Matsumiya, Negin Yavari, Irmak Karaca, Cigdem Yasar, Sherin Lajevardi, Brandon Huy Pham, Diana V Do, Quan Dong Nguyen; Effect of pupil size on fixed-luminance flicker full-field electroretinogram magnitude. Invest. Ophthalmol. Vis. Sci. 2021;62(8):607.
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Diopsys® NOVA fixed-luminance flicker full-field electroretinogram (ffERG) is a potential alternative to classic ffERG testing for measuring the electrical activity of cone cells . Pupil size has been shown to effect electrical response. The index study aims to quantify the relationship between pupil size and ffERG magnitude using this device.
12 patients (24 eyes) with no known ocular diseases were enrolled in the study. Retinal activity was examined using Diopsys® ffERG before and after dilation. Eyes were initially anesthetized with proparacaine hydrochloride 0.5 % ophthalmic solution and then dilated with tropicamide 1% and phenylephrine 2.5% ophthalmic solutions. Eyes were dilated to a minimum of 5 mm before Diopsys® measurements were made. Paired t-test and robust linear regression were performed on the data set.
Mean age was 34.9±8.4 years and 25% were female. Mean value of pupil diameter and magnitude before and after the dilation was 2.54 ± 0.38 mm/7.01 ± 0.90 mm and 10.45 ± 2.92 µV /16.56 ± 4.1 µV , respectively. There was a statistically significant difference in magnitude of response before and after dilation (p: <0.0001). In dilated eyes, linear regression analysis demonstrated an increase in magnitude with each millimeter increase of pupil size (r2: 0.44; Coeff.: 2.99; p: <0.0001) (figure1). It also demonstrated a 12% increase in change of magnitude with each millimeter unit increase in pupil size (r2: 0.15; Coeff.: 1.12; p: 0.07) (figure2).
Pupil size affects electrophysiologic response of the retina and should be measured and documented. Physicians should take pupil size into consideration when making clinical judgments based on Diopsys® ffERG. The normative values for ffERG devices should include pupil size variability to ensure better clinical judgments.
This is a 2021 ARVO Annual Meeting abstract.
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