Objective Assessment of Local Retinal Function by Focal Macular and Multifocal Electroretinograms

There are two clinically methods to record electroretinographic (ERG) responses from focal areas of the retina; the focal macular ERGs (fmERGs) (Hirose et al., 1977; Miyake et al., 1989a; Miyake 1998) and multifocal ERGs (mfERGs).(Sutter &Tran 1992;Sutter et al., 1999; Hood &Greenstein 2003) Each technique has advantages and disadvantages. For example, fmERGs can be used to assess the function of different layers of localized areas of the retina, while mfERGs can be used to assess the function of different localized areas of the macula. These two techniques have been extensively investigated to determine their abilities to detect and assess functional alterations in different retinal areas in different retinal diseases. The results of these studies combined with the morphological findings of the same retinas determined by optical coherence tomography (OCT) have led to significant advances in the diagnosis and treatment of macular diseases. This chapter reviews the findings made by these two techniques, and show how they have advanced the diagnosis and therapy of macular diseases.