Figure 82-9 The electroretinogram (ERG) in central retinal arterial occlusion. The ERG is recorded under varying scotopic conditions. The ERG is shown before, during, and after ischemia, up to 7 days later. (From Roth S, Li B, Rosenbaum PS, et al: Preconditioning provides complete protection against retinal ischemic injury in rats. Invest Ophthalmol Vis Sci 39:777, 1998).