Elevated energy requirement of cone photoreceptors

Significance From recent measurements of mammalian cone physiology, we have calculated cone ATP utilization in darkness and in the light. We show that single cones consume ATP at a much higher rate than single rods, a difference that is greatly increased during the day. This high metabolic rate is especially prominent in the primate fovea, which may make this part of the human eye particularly sensitive to decreases in glucose uptake or other metabolic alterations.