 A variety of studies demonstrate that ocular blood flow is altered in glaucoma. Various animal and human studies have shown an increase in retinal and optic nerve head blood flow in response to diffuse luminance flicker. Based on studies with ERG, this effect has been attributed to augmented activity in the retinal ganglion cells and associated axons indicating a coupling mechanism between neuronal activity and retinal blood flow. Whereas a variety of studies have confirmed these effects, the knowledge about this coupling in the retina of patients with glaucoma is sparse. 