Evaluation of scotopic and photopic function using a mydriasis-free, portable system for recording electroretinograms

Abstract

Purpose : The full-field electroretinogram (ERG) is widely used clinically to evaluate retinal function by recording electrical potentials generated by retinal cells in response to flash stimuli. Conventional ERG recordings require mydriatics and are not easily obtained in young children who may require sedation or in those with developmental disability. The purpose of this prospective, cross sectional study was to determine the intra-visit reliability and diagnostic capability of a hand-held, mydriasis-free ERG, RETeval, in comparison to the clinical full-field ERG by measuring responses recommended by ISCEV.

Methods : Thirty-four patients (median age= 13 years, range: 6 months–59 years) who had undergone ISCEV Standard ERG were recruited at SickKids. For RETeval, pupils were undilated and sensor strip electrodes were placed under the inferior orbital rim. Stimulus settings on RETeval were equivalent to those used in the Standard ISCEV ERG. Forty-three control participants (median age= 22 years, range: 9–65 years) with no known retinal disease were recruited from the general population to establish standard values for comparison; for those aged 3 years and under, age matched lab data formed ERG standard control values. Amplitudes <5th centile, or implicit times >95th centile of normal relative to control data were classified as abnormal in patients.

Results : The RETeval system demonstrated a high degree of within-visit reliability with an intraclass correlation coefficient (ICC) of 0.91 for amplitudes and 0.58 for implicit times. Cohen’s Kappa analysis revealed a substantial level of agreement between the diagnostic capability of RETval in comparison to clinical full-field ERG (k = 0.822), with a sensitivity and specificity of 0.93 and 0.89 respectively. Pearson’s correlations for clinical full-field ERG versus RETeval demonstrated a strong positive correlation for amplitudes of both the rod (r = 0.87) and cone (r = 0.81) responses.

Conclusions : The present study demonstrated that RETeval flash ERG is a reliable tool with reasonable accuracy in comparison to the clinical standard. The avoidance of sedation and pupillary dilation enhances patient comfort and cooperation, while the portable nature of the RETeval system enables its incorporation not only at SickKids but also centres that do not have established visual electrophysiology units and resource limited areas of the world.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.