Accuracy and results of photopic flash electroretinogram performed with skin electrodes in infants

Abstract

Purpose As it is not always possible to use corneal electrodes for recording electroretinograms (ERG) in children, it is necessary to check the feasibility of performing ERG with skin electrodes and to try to establish normative data. Methods Fifty-one healthy children (aged 7-11 years) were recruited. Cone ERG and 30-Hz flicker ERG were recorded with one active skin electrode positioned over the lower eyelid and a reference electrode at the outer canthus of the eye. Responses were recorded to full-field stimuli. Correlations between results of both eyes were studied. Results were compared to normative data obtained with corneal electrodes. Results Cone ERG response was obtained in 100/102 eyes. Flicker ERG was obtained in 88/102 eyes. No correlation between eyes was found for the a-wave latency, the a-wave amplitude, and the latency of the flicker. Mean b-wave implicit time of the cone ERG was 38.71±1.6 ms; the median of its amplitude was 10.0 µV. The median of the amplitude of the flicker ERG was 12.55 µV. Conclusions Amplitudes are significantly reduced, with a scaling factor of 8.75 for the b-wave amplitude of the cone ERG compared to corneal electrodes (9.6 for the a-wave amplitude and 8.87 for the flicker amplitude). Our study contributes to the establishment of normative data for skin electrode ERG. It emphasizes the feasibility and accuracy of this method. It is very useful to assess the normality of the ERG in many clinical situations, such as nystagmus and suspicion of delayed visual maturation.