OBJECTIVE: To assess central and peripheral retinal and choroidal diseases using ultra-widefield (UWF) fundus imaging in combination with navigated central and peripheral cross-sectional and three-dimensional (3D) swept source optical coherence tomography (SS-OCT) scans.
METHODS: Retrospective study involving 332 consecutive patients, with a nearly equal distribution of males and females. The mean age of patients was 52 years (range 18-92 years). Average refractive error was -3.80 D (range +7.75 to -20.75 D).
RESULTS: The observations in this study demonstrate the efficacy of peripheral navigated SS-OCT in assessing various ocular conditions. The technology provides high-quality images of the peripheral vitreous, vitreoretinal interface, retina, and choroid, enabling visualization of vitreous floaters and opacities, retinal holes and tears, pigmented lesions, and peripheral retinal degenerations. 3D OCT scans enhance the visualization of these abnormalities and improve diagnostic and therapeutic decisions.
CONCLUSIONS: Navigated central and peripheral cross-sectional and 3D SS-OCT scans offer significant complementary benefits in the assessment and management of retinal diseases. Their addition to UWF imaging provides a comprehensive view of central and peripheral ocular structures, aiding in early detection, precise anatomical measurements, and objective monitoring of disease progression. In addition, this technology serves as a valuable tool for patient education, a teaching tool for trainees, and documentation for medico-legal purposes.

OBJECTIVE: To utilize ultra-widefield multimodal imaging (Optos PLC) to describe novel findings in degenerative retinoschisis.
METHODS: This retrospective, non-comparative case series of degenerative retinoschisis received a waiver of consent from Advarra IRB, Protocol 00066379. Initial ultra-widefield pseudocolour, colour-separated, autofluorescence, and peripheral OCT imaging were analysed for characterizing features.
RESULTS: In total, 139 eyes were included. A hyporeflective reticular pattern associated with retinoschisis was seen on pseudocolour images in 39% of cases, but visible in 53% on green-separated images. Fine hyper-reflective foci were observed in 49%. In 27%, retinoschisis was confirmed with OCT.
CONCLUSIONS: Ultra-widefield pseudocolour and green-separated images are valuable for the diagnosis and characterization of degenerative retinoschisis. The findings described may prompt the evaluation of subtle retinoschisis with peripheral OCT.

Behavior differs across individuals, ranging from typical to atypical phenotypes.1 Understanding how differences in behavior relate to differences in neural activity is critical for developing treatments of neuropsychiatric and neurodevelopmental disorders. One hypothesis is that differences in behavior reflect individual differences in the dynamics of how information flows through the brain. In support of this, the correlation of neural activity between brain areas, termed \"functional connectivity,\" varies across individuals2 and is disrupted in autism,3 schizophrenia,4 and depression.5 However, the changes in neural activity that underlie altered behavior and functional connectivity remain unclear. Here, we show that individual differences in the expression of different patterns of cortical neural dynamics explain variability in both functional connectivity and behavior. Using mesoscale imaging, we recorded neural activity across the dorsal cortex of behaviorally \"typical\" and \"atypical\" mice. All mice shared the same recurring cortex-wide spatiotemporal motifs of neural activity, and these motifs explained the large majority of variance in cortical activity (>75%). However, individuals differed in how frequently different motifs were expressed. These differences in motif expression explained differences in functional connectivity and behavior across both typical and atypical mice. Our results suggest that differences in behavior and functional connectivity are due to changes in the processes that select which pattern of neural activity is expressed at each moment in time.

This review provides an overview of conventional and novel retinal imaging modalities for hydroxychloroquine (HCQ) retinopathy. HCQ retinopathy is a form of toxic retinopathy resulting from HCQ use for a variety of autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Each imaging modality detects a different aspect of HCQ retinopathy and shows a unique complement of structural changes. Conventionally, spectral-domain optical coherence tomography (SD-OCT), which shows loss or attenuation of the outer retina and/or retinal pigment epithelium-Bruch\'s membrane complex, and fundus autofluorescence (FAF), which shows parafoveal or pericentral abnormalities, are used to assess HCQ retinopathy. Additionally, several variations of OCT (retinal and choroidal thickness measurements, choroidal vascularity index, widefield OCT, en face imaging, minimum intensity analysis, and artificial intelligence techniques) and FAF techniques (quantitative FAF, near-infrared FAF, fluorescence lifetime imaging ophthalmoscopy, and widefield FAF) have been applied to assess HCQ retinopathy. Other novel retinal imaging techniques that are being studied for early detection of HCQ retinopathy include OCT angiography, multicolour imaging, adaptive optics, and retromode imaging, although further testing is required for validation.

OBJECTIVE: To assess the capillary non-perfusion in different concentric sectors on widefield optical coherence tomography angiography (WF-OCTA) and to correlate the ratio of non-perfusion (RNP) to the severity of sickle cell retinopathy (SCR).
METHODS: This retrospective, cross-sectional study included eyes of patients with various sickle cell disease (SCD) genotypes having undergone WF-OCTA and ultra-widefield color fundus photography (UWF-CFP). Eyes were grouped as no SCR, non-proliferative SCR or proliferative SCR. RNP was assessed on WF-OCTA montage in different field-of-view (FOV) sectors centered on the fovea: 0-10-degrees circle excluding the foveal avascular zone, the 10-30-degrees circle excluding the optic nerve, the 30-60-degrees circle, and the full 60-degrees circle.
RESULTS: Forty-two eyes of twenty-eight patients were included. Within each SCR group, mean RNP of the FOV 30-60 sector was higher than all other sectors (p < 0.05). Mean RNP of all sectors were significatively different between no SCR group and proliferative SCR group (p < 0.05). To distinguish no SCR versus non-proliferative SCR FOV 30-60 had a good sensitivity and specificity of 41.67% and 93.33%, respectively (cutoff RNP > 22.72%, AUC = 0.75, 95% CI 0.56-0.94, p = 0.028). To differentiate non-proliferative versus proliferative SCR, FOV 0-10 had good sensitivity and specificity of 33.33% and 91.67%, respectively (cutoff RNP > 18.09, AUC = 0.73, 95% CI 0.53 to 0.93, p = 0.041). To discern no SCR versus proliferative SCR, all sectors had optimal sensitivity and specificity (p < 0.05).
CONCLUSIONS: WF OCTA-based RNP provides non-invasive diagnostic information regarding the presence and severity of SCR, and correlates with disease stage in certain FOV sectors.

Advances in optical technology have revolutionized studies of brain function in freely behaving mice. Here, we describe an optical imaging and stimulation device for use in primates that easily attaches to an intracranial chamber. It consists of affordable commercially available or 3D-printed components: a monochromatic camera, a small standard lens, a wireless μLED stimulator powered by an induction coil, and an LED array for illumination. We show that the intrinsic imaging performance of this device is comparable to a standard benchtop system in revealing the functional organization of the visual cortex for awake macaques in a primate chair or under anesthesia. Imaging revealed neural modulatory effects of wireless focal optogenetic stimulation aimed at identified functional domains. With a 1 to 2 cm field of view, 100× larger than previously used in primates without head restraint, our device permits widefield optical imaging and optogenetic stimulation for ethological studies in primates.

Imaging is an integral part of the evaluation and management of retinal disorders. Each imaging modality has its own unique capabilities and can show a different aspect or perspective of disease. Multimodal retinal imaging provides a wealth of substantive and insightful information; however, the integration of all this complex data can be overwhelming. We discuss the applications and the strengths and limitations of the many different retinal imaging tools that are approved for clinical use. These modalities include color fundus photography, widefield imaging, fundus autofluorescence, near infrared reflectance, optical coherence tomography angiography, and en face optical coherence tomography. We also cover the advantages and disadvantages of a multimodal approach.

Spontaneous neuronal activity strongly impacts stimulus encoding and behavioral responses. We sought to determine the effects of neocortical prestimulus activity on stimulus detection. We trained mice in a selective whisker detection task, in which they learned to respond (lick) to target stimuli in one whisker field and ignore distractor stimuli in the contralateral whisker field. During expert task performance, we used widefield Ca2+ imaging to assess prestimulus and post-stimulus neuronal activity broadly across frontal and parietal cortices. We found that lower prestimulus activity correlated with enhanced stimulus detection: lower prestimulus activity predicted response versus no response outcomes and faster reaction times. The activity predictive of trial outcome was distributed through dorsal neocortex, rather than being restricted to whisker or licking regions. Using principal component analysis, we demonstrate that response trials are associated with a distinct and less variable prestimulus neuronal subspace. For single units, prestimulus choice probability was weak yet distributed broadly, with lower than chance choice probability correlating with stronger sensory and motor encoding. These findings support low amplitude and low variability as an optimal prestimulus cortical state for stimulus detection that presents globally and predicts response outcomes for both target and distractor stimuli.

Age-related macular degeneration (AMD) is a progressive neuro-retinal disease and the leading cause of central vision loss among elderly individuals in the developed countries. Modern ocular imaging technologies constitute an essential component of the evaluation of these patients and have contributed extensively to our understanding of the disease. A challenge with any review of ocular imaging technologies is the rapid pace of progress and evolution of these instruments. Nonetheless, for proper and optimal use of these technologies, it is essential for the user to understand the technical principles underlying the imaging modality and their role in assessing the disease in various settings. Indeed, AMD, like many other retinal diseases, benefits from a multimodal imaging approach to optimally characterize the disease. In this chapter, we will review the various imaging technologies currently used in the assessment and management of AMD.

Vagus nerve stimulation (VNS) is used for management of a variety of neurological conditions, although the therapeutic mechanisms are not fully understood. Accumulating evidence suggests that VNS may modulate cortical state and plasticity through activation of broadly projecting neuromodulatory systems. Using a mouse model, we compared arousal-linked behaviors with dorsal cortical activity obtained with widefield and two-photon GCaMP6s calcium imaging and electrophysiological recordings. We observed robust and reliable cortical and behavioral dose-dependent activation in waking mice to VNS, including pupil dilation and, frequently, whisker movements and locomotion. Widefield calcium imaging and multiunit recording during VNS revealed that this observed increase in arousal state is coupled with a rapid and widespread increase in excitatory activity, including, but not limited to, activation of somatosensory, visual, motor, retrosplenial, and auditory cortical regions. Two-photon GCaMP6s calcium imaging of cholinergic and noradrenergic cortical axons revealed that VNS strongly activates these neuromodulatory systems. Importantly, VNS-evoked activation of neuromodulatory axons and excitatory neurons in the cortex persisted in mice under light anesthesia, in the absence of overt movement. Arousal state changes were abolished by vagus nerve transection, confirming that observed VNS effects were specific to nerve stimulation and triggered widespread activity above that which can be explained by motor activity. Taken together, our results support a model of VNS in which activation of subcortical structures leads to widespread activation of cortex and an increase in arousal state, at least partially due to the activation of cholinergic and noradrenergic modulatory pathways.