Saccades orchestrate intraocular glucose dynamics to shape visual responses in birds

Birds exhibit remarkable vision despite lacking the classical retinal vasculature, raising an enigmatic question about how avascular retinas fulfill energy demands necessary for sight. Avian saccades couple rapid gaze shifts with cyclotorsional oscillations. In pigeons, we show that these saccades orchestrate intraocular metabolic dynamics and visual processing. Using combined measurements of eye movements, intraocular glucose, and neuronal activity in retinorecipient brain regions, we found that saccades induce intraocular glucose fluctuations that are closely linked to changes in visual responses over seconds to minutes. Pharmacologically manipulating glucose availability or eliminating saccadic oscillations produced corresponding changes in neuronal responses, demonstrating causality. Thus, stimulus-driven saccades not only serve visual exploration but also propel retinal metabolism, facilitating neuronal visual responses in the absence of retinal vasculature. These findings underscore an intrinsic interplay among eye movements, metabolic regulation, and visual function, offering insight into how oculomotor behavior supports retinal health and visual performance across species. How do avian eyes fulfill the intense metabolic activity of thick, high-acuity retinas in the absence of direct vascular support? The study finds that birds’ rapid, oscillating saccadic eye movements pump glucose from the pecten to the avascular retina, sustaining nutrient supply and boosting visual responses in the brain; especially when driven by dynamic visual stimuli.