Introduction to mfERGs
The typical stimulus for multifocal electroretinogram (mfERG) is shown in the left image above. Usually, 103 hexagons pattern reverse from white to black and black to white in a pseudo- random sequence. The resultant response from the retina is a topographically accurate ERG from 103 different locations. The total field size often chosen is one that grossly corresponds to the standard 24-2 visual field (which is 54 degrees horizontal and 48 degrees vertical). The amplitude of the mfERG components are color coded for rapid interpretation. The traditional color coding is employed: Bright colors correspond to high amplitude areas whereas dark colors represent low amplitude zones. White and red are hence large amplitude responses, light green is normal but blue is reduced.