Documenta Ophthalmologica 92: 281-289, 1997. (~) 1997 Kluwer Academic Publishers. Printed in the Netherlands. 281 Comparison of repeatability of the multifocal electroretinogram and Humphrey perimeter STUART PARKS 1,2, DAVID KEATING 1'2, ALED L. EVANS 3, THOMAS H. WILLIAMSON l, JEFFREY L. JAY 1 & ALEX T. ELLIOTT 2 ITennent Institute of Ophthalmology, West Glasgow University NHS Trust, Glasgow, Scotland; 2Deparment of Clinical Physics and Bio-engineering, University of Glasgow; 3Department of Clinical Physics and Bio-engineering, Southern General Hospital, Glasgow, Scotland R~ceived 13 September 1996; accepted in revised form 18 April 1997 Key words: comparison, electroretinogram, focal, multifocal, perimetry, repeatability Abstract. Functional mapping of the retina by multifocal electroretinographic recordings is now possible. We compared the normal range, repeatability and response topography of this new technique with conventional static Humphrey perimetry to assess its suitability in clinical practice. The multifocal technique was performed on 60 age-matched controls. Measures of repeat~/bility and reproducibility were obtained. Results were then compared with those obtained from a customized perimetry test. In both tests the coefficients of repeatability were found to decrease with eccentricity. The inherent measurement variation between techniques was comparable. Overall system variation indicates that the technique could be a useful tool at the clinical level. Introduction The Visual Evoked Response Imaging System (VERIS) exploits the new technique of multifocal stimulation in the detection and monitoring of retinal disorders. The system's advantage over conventional electrophysiology is its sensitivity to localized retinal abnormalities. While this was possible with the focal electroretinogram (ERG), the multifocal technique enables concurrent stimulation, thus avoiding the spatially varying signal-to-noise ratios inherent in the focal ERG. Its ability to stimulate, simultaneously, large numbers of retinal areas has established the technique, and the VERIS system, as a useful research tool. However, its suitability for the routine clinical setting has not been fully addressed, and this work represents a thorough investigation and evaluation of the system in this context. To achieve this, it was necessary to answer a number of fundamental questions. First, to establish the normality or abnormality of any retinal area stimulated by the system, a normal age- matched range had to be defined for each area. Second, to establish whether any change in a measurement in a repeated test resulted from progression or