Abstract
Purpose :
Electroretinography (ERG) assesses retinal function and is useful in diagnosing hereditary retinal disorders. However its use is limited in children by cost, test availability, and general anesthesia (GA) risks. We prospectively evaluated a handheld ERG device (RETeval) as a screening tool and compared it to conventional ERG under GA in children.
Methods :
We enrolled 16 children undergoing full-field ERG under GA at an academic eye institute. Prior to GA, all patients underwent RETeval 30-Hz cone flicker ERG testing using skin electrodes, with a standard international stimulus (3 cd-s/m2 white flash, 30 cd/m2 white background, frequency 28.3 Hz). A standard full-field ERG using bipolar Burian-Allen contact lens electrodes with a handheld stimulus using a conventional ERG system (E3 Diagnosys) under GA was performed. Subsequently, RETeval 30-Hz flicker skin electrode testing was repeated. The amplitudes and implicit times of the three 30-Hz cone flicker recordings were compared using Bland-Altman plot analysis and Pearson correlation.
Results :
Of the 16 patients (mean age 4 years, 4 retinitis pigmentosa, 2 achromatopsia, 2 Leber congenital amaurosis, 1 on vigabatrin), 8 had normal range Diagnosys cone flicker responses. For all patients, the RETeval amplitudes were smaller when awake (mean -38.3 uV, SD 36.8, limit of agreement 95% CI -111.8 to 35.2, Pearson r=0.60) and under GA (-29.5 uV, SD 34.5, 95% CI -98.5 to 39.6, r=0.7) than the Diagnosys. For the 8 patients with normal Diagnosys responses, the RETeval responses were substantially lower. The RETeval implicit times were longer when awake (+1.2 ms, SD 7.7 ms, 95% CI -14.2 to 16.6 ms, r=0.3) and under GA (+2.3 ms, SD 6.0 ms, 95% CI -9.7 to 14.3 ms, r=0.5) than the Diagnosys. When comparing RETeval values prior to and under GA, amplitudes were lower under GA than awake (-3.4 uV, SD 6.5, 95% CI -16.4 to 9.6, r=0.61), and the implicit times were shorter when awake than under GA (-2.1 ms, SD 8.7 ms, 95% CI -19.4 to 15.3 ms, r=0.38).
Conclusions :
The 30-Hz cone flicker ERG screening test using the RETeval in children has smaller and prolonged responses than the conventional cone flicker ERG responses under GA. This is likely due to differences between skin and contact lens electrodes. When the responses of the RETeval cone flicker screening test are impaired, a conventional ERG using the full international protocol should be performed.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.