Using a near-infrared (NIR) light flood-illumination imager equipped with a high-speed (120Hz) CCD camera, we demonstrated optical imaging of stimulus-evoked retinal activity in isolated, but intact, frog eye. Both fast and slow transient intrinsic optical signals (IOSs) were observed. Fast optical response occurred immediately after the stimulus onset, could reach peak magnitude within 100ms, and correlated tightly with ON and OFF edges of the visible light stimulus; while slow optical response lasted a relatively long time (many seconds). High-resolution images revealed both positive (increasing) and negative (decreasing) IOSs, and dynamic optical change at individual CCD pixels could often exceed 10% of the background light intensity. Our experiment on isolated eye suggests that further development of fast, high (sub-cellular) resolution fundus imager will allow robust detection of fast IOSs in vivo, and thus allow noninvasive, three-dimensional evaluation of retinal neural function.