Important Differences in Methodology and Reliability of the Electro-oculogram and the Electroretinogram in Psychiatric Research

See the paper

Marc Hébert, Michel Maziade

We appreciate the comments of Dr. Fountoulakis on our study of electroretinogram (ERG) response in young nonaffected offspring at high risk to develop a psychiatric disorder (). The comments give us an opportunity to discuss the important methodological differences between ERG and electro-oculogram (EOG) that we briefly summarized in the following paragraphs. Based on his experience in EOG, Dr. Fountoulakis argues that the amplitude measures from ERG we reported lack reliability and that we misinterpreted the observed ERG. Dr. Fountoulakis also suggests that the initial cause of our defective response observed with the ERG could originate at the level of the retinal pigment epithelium (RPE), which, in turn, could cause a secondary impact on photoreceptors.