A schematic of the imaging instrument is shown in Fig. 1(a). The animal was secured in a stereotaxis to eliminate motion, and mineral oil was placed on the surface of the cornea to prevent dryness. The endoscope (5-mm diameter, 11.5-cm length, Karl Storz 67260AA, Tuttlingen, Germany), depicted from different angles in Figs. 1(c) and 1(d), was then placed directly in contact with the mineral oil, carefully avoid pressuring the corneal surface. A laser diode (785 nm, Thorlabs, Newton, New Jersey) connected to the fiber-optic input was used to deliver light through the endoscope onto the eye using a ring-shaped illumination pattern. We would not expect the light to affect the optical properties or the physiology of the eye. The scattered laser light was captured by the CMOS camera (Basler 602f, , Basler, Ahrensburg, Germany) connected to the endoscope using a custom lens adapter (SN# OY620143-A). For green-light reflectance images, the laser diode was replaced with a green LED and delivered using a fiber-optic guide. Images from the camera were collected at a rate of 70 frames per second and an exposure time of 5 ms using custom written software. During functional activation, a slightly altered setup was used, as shown in Fig. 1(b). The 530-nm light from a green LED was combined with the laser diode output using a dual-branch light guide (Edmund Optics, Barrington, New Jersey). Figure 1(e) shows a photograph of the system in use.