With the patient’s distance prescription in place (with an additional +1.00 D to compensate for the 1 meter working distance), the central 5 degrees of the visual field is focused onto the central 5 degrees of the fundus which corresponds to the macula. Action potentials are then generated by the ganglion cells which are transmitted through the visual pathway to the occipital lobe. Note that the central 5 degrees of the visual field (in orange and yellow) project onto about 50% of the occipital lobe! Hence, the VEP is a test of macula and macula projections measured at the level of the occipital lobe with surface electrodes. VEPs are often far more sensitive than visual fields to optic neuropathies affecting the papillo-macular bundle (PMB) but also in cases without any evidence of PMB compromise. Diopsys VEPs are far simpler to obtain than traditional VEPs.