Multifocal Electroretinography (mERG): Normative values and a new clinical analysis procedure

Abstract

 

The purpose of this study was to increase the detection sensitivity of mild pathological changes and age-related normal changes in multifocal electroretinography (mERG). These goals were achieved by measuring normative values for a wide age range and by creating a clinical analysis procedure for patients with mild pathological changes in their mERG-responses. The effect of age on the peak-to-peak amplitude and P1 implicit time of the mERG-responses was studied in 92 healthy subjects distributed about evenly across the adult age groups (minimum of 18 subjects in each age decade between the years of 20 and 68). For the purpose of clinical use, a new analysis program — mERGmark — was created. With this new analysis tool, peaks are detected either automatically or manually and comparisons to age-related normal values are color-coded and summarized according to the scaling method used in the Octopus 101 automated visual field perimeter. This new analysis tool allows us to directly compare the mERG maps and the measured visual fields together and to project them on subjects' digital retina photographs. This clinical analysis procedure was tested with a group of patients exhibiting mild to strong changes in their mERG-responses. Peak-to-peak P1 amplitude decreased and implicit time increased with the age. There were topographical differences in the amplitude decrease between age groups. Thus, there is a need for an age-related normative data bank if very mild pathological changes are studied.