Visual perception in night vision is rod-mediated thus, delayed dark adaptation due to impaired rod photoreceptor homeostasis is often the earliest symptom of various retinal diseases, such as age-related macular degeneration (AMD) 7, diabetic retinopathy (DR) 8, and retinitis pigmentosa (RP) 9, the leading causes of irreversible vision loss. During dark adaptation, multiple processes simultaneously occur to maintain retinal homeostasis, including photoreceptor repolarization 2, photopigment regeneration 2, blood flow modulation 3, a redistribution of photoreceptor signaling proteins 4 and interphotoreceptor matrix proteins 5, and a reversal of metabolic energy flow 6. Functional OCT of dark adaptation kinetics promises an objective method for rapid ORG assessment of physiological integrity of retinal photoreceptors.ĭark adaptation refers to a systematic recovery of visual sensitivity in the dark following exposure to bright lights 1. A strong positive correlation between the outer retinal shortening and ISe intensity reduction was also confirmed. Functional OCT revealed a shortening of the outer retina, a rearrangement of the cone and rod photoreceptor interdigitation zone, and a reduction in intrinsic signal amplitude at the photoreceptor inner segment ellipsoid (ISe). Here we demonstrate functional optical coherence tomography (OCT) for in vivo intrinsic signal optoretinography (ORG) of dark adaptation kinetics in the C57BL/6J mouse retina. However, there is a lack of noninvasive methods capable of spatiotemporal monitoring of photoreceptor changes during dark adaptation. Objective measurement of dark adaptation can facilitate early diagnosis to enable prompt intervention to prevent vision loss. Delayed dark adaptation due to impaired rod photoreceptor homeostasis has been reported as the earliest symptom of eye diseases such as age-related macular degeneration, diabetic retinopathy, and retinitis pigmentosa.