Topographical Analysis of the Retina Using Visual Evoked Response Imaging System (Veris)

Abstract

The Visual Evoked Response Imaging System (VERIS) was introduced by Sutter and Tran (1992) and presents a new method of recording and analyzing the multifocal electroretinogram (ERG). Because it is new, several issues need to be addressed for the method to be useful in clinical application. The purpose of this thesis is to address some of these issues which include: i) type of electrodes used in the VERIS system, ii) effect of patient age on the multifocal electroretinogram, iii) sensitivity of the VERIS system in detecting abnormal retinal conditions. Four different electrode types were used to record the multifocal ERG and responses from different areas of the retinal field were compared. The areas were divided into a central area and five adjacent concentric rings around the centre. The JET contact lens electrode and the gold foil electrode produced the highest amplitude response densities for the central area and the 2nd concentric ring which were significantly higher than the amplitude densities for the DTL thread and carbon-glide electrodes. For the 1st concentric ring however the amplitude response density for the JET contact lens was higher than the amplitude densities of all the other electrodes. For all electrodes, no significant differences in amplitude densities obtained from the 3rd to 5th concentric rings were found.