PROJECT SUMMARY Injuries to the optic nerve damage or sever the axons of retinal ganglion cells (RGCs), leading to vision loss that is currently irreversible. While optic nerve regeneration in a major research area, little is known about the early functional changes to RGCs that precede cell death. Strategies to restore vision, as well as improved diagnostics, require more detailed information about the time course of changes in RGC spike responses after optic nerve injury. I propose to address this knowledge gap by developing a new preparation of the intact mouse eye and its supporting vasculature. We are working to adapt an isolated, perfused eye preparation that has been published in larger eyes, into the mouse while simultaneously using high-density electrodes to record spikes from the optic nerve. Aim 1 will validate the successful functional identification of RGCs using opto-tagging. Aim 2 will measure the time course of dysfunction in identified RGCs following optic nerve cut while experimentally varying the location of the cut along the nerve. The successful completion of this project will establish a new preparation with advantages over existing preparations for studies of the earliest RGC dysfunction in retinal disease.