Abstract
To assess the RETeval (LKC Technologies, Gaithersburg, MD) handheld electroretingram (ERG) device as a screening tool for cone dysfunction in pediatric patients by comparing it to conventional ERG.
Patients scheduled for ERG under general anesthesia (GA) underwent three tests: (1) RETeval standard 30 Hz cone flicker ERG using skin electrodes prior to GA, (2) E3 Diagnosys (Diagnosys LLC, Lowell, MA) conventional complete standard protocol full-field ERG using bipolar contact lens electrodes and handheld stimulus under GA, and (3) repeat RETeval testing under GA. The 30 Hz cone flicker amplitudes and implicit times from the three methods were compared. Negative and positive predictive values were calculated by applying a previously established 5 μV amplitude cut-off.
Thirty patients ≤18 years of age were enrolled. Impaired conventional ERGs were found in 18 patients. Compared to conventional ERG under GA, RETeval cone flicker amplitudes were smaller before GA (mean difference, -42.2 ± 45.3 μV) and under GA (-37.1 ± 44.5 μV), likely due to skin electrode; and implicit times were shorter before GA (-1.06 ± 2.83 ms) and longer under GA (1.28 ± 4.12 ms), likely due to GA. Comparing RETeval responses before and under GA, the amplitudes were lower (-3.05 ± 6.82 μV), and implicit times were shorter (-2.25 ± 3.28 μV) before GA. Overall, the positive predictive value of the RETeval was 85%; the negative predictive value, 90%.
The unsedated handheld RETeval 30 Hz cone flicker ERG is a feasible screening test for detecting cone dysfunction in pediatric patients. Full-protocol ERG is needed when screening ERG is reduced, equivocal, or clinically warranted.
