The multifocal ERG (mfERG) and the multifocal VEP (mfVEP) are two new tests for objective mapping of visual function. Both have already proven useful for the diagnosis and management of glaucoma and optic nerve disease. In these clinical applications, both techniques have their advantages and limitations. The mfVEP suffers from lower signal-to –noise ratio, larger inter-subject variability and local signal dropout due to the convoluted cortical anatomy. As the technique only provides amplitude and latency estimates, it does not always show where along the retino-cortical pathway a dysfunction is located. The mfERG, on the other hand, provides better coverage of the visual field and easily distinguishes between diseases affecting the distal retina and those affecting ganglion cell and optic nerve function. Most of the mfERG signal originates from retinal sources that are not affected in glaucoma and optic nerve disease and the response contribution from ganglion cells must be accurately estimated. The identification and extraction of a ERG component from ganglion cell axons near the optic nerve head (ONHC) has led to the development of promising mfERG protocols for glaucoma. An evaluation of these techniques is currently under way

To illustrate the differences between mfERG and mfVEP techniques, this presentation will cover a comparative evaluation on the same patients. Multifocal stimulation techniques for the enhancement of ganglion cell contribution to the mfERG and new mfVEP analysis techniques will be discussed.