PROJECT SUMMARY The oxygen-induced retinopathy (OIR) model has been a valuable preclinical model for understanding the pathophysiology of retinopathy of prematurity (ROP) and ischemic retinopathies in general. Through ex vivo histologic evaluation of the nonperfusion area (NPA) and neovascularization area (NVA), OIR provides a quantitative model for evaluating therapeutic interventions that modulate tissue response to ischemic injury and neovascularization, both of which are common to multiple retinal vascular diseases. Advances in visible-light OCT (vis-OCT) have recently demonstrated the potential to provide not only in vivo quantitative OCT angiography (OCTA), but also measurement of total retinal blood flow (TRBF) and oxygen saturation (sO2) oximetry in preclinical rat models. In this proposal, we will develop a new wide-field (WF) vis-OCT device optimized for the rat eye to evaluate the relationship between the traditional OIR biomarkers (NPA and NVA) ex vivo and WF-vis-OCT measured TRBF, arterial and venous sO2, and NPA and NVA. We will accomplish this through three specific aims. 1) Develop WF-vis-OCT. We will build a new vis-OCT system that can provide 5- µm transverse resolution over a 130-degree field of view, by integrating a wide-field imaging probe that includes a custom contact objective lens. 2) Develop deep-learning-aided quantitative OCT angiography and oximetry. We will develop an end-to-end network for segmenting 2D and 3D capillary vasculature on vis-OCTA, which will enable the quantification of NPA and NVA in the rat OIR model. The retinal vascular sO2 and TRBF obtained from the new device will be further validated with an oxygen challenge study on normal rat retinas in vivo andamicrofluidicchipinvitro.3)EvaluationofratOIRmodelusingWF-vis-OCTbiomarkers.Inacross- sectional study design, we will first compare vis-OCT biomarkers (TRBF, sO2, NPA, and NVA) with traditional histological markers in the OIR model (NPA and NVA). We will then longitudinally evaluate two therapeutic interventions in vivo using the newly established vis-OCT rat OIR model. First, based on the hypothesis that hypoxia is the driving pathologic mechanism for NV development in phase II of the disease, we will evaluate the effect of maintaining the rat in a high oxygen environment on TRBF, sO2, NPA, and NVA. Second, based on the known therapeutic benefit of anti-vascular endothelial growth factor (anti-VEGF) in phase I OIR, we will evaluate the effect of intravitreal anti-VEGF delivery on vis-OCT biomarkers. If successful, this work will lead to improving our understanding not only of ROP pathophysiology, but will provide a novel scientific methodology for in vivo assessment of therapeutic interventions for ischemic retinopathies such as diabetic retinopathy, which often use the OIR model for preclinical investigation.