SCD REVIVE - Retina to Evaluate Vaso occlusion In the Vasculature of the Eye

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Sickle Cell Disease (SCD) is a high-morbidity, beta-globin blood disorder that causes hemolysis and vaso- occlusion, leading to pain, organ damage and premature death. A key barrier to progress is that current disease-monitoring biomarkers correlate weakly with clinical outcomes because they do not directly measure the mechanisms that cause clinical pathology. The transparent media of the eye presents the opportunity to directly visualize the retinal microvasculature, as an indirect representation of the microvascular status of other organ systems and to quantify transient interruptions in blood flow (a major cause of SCD pathology). Our group found that new approaches to quantifying retinal perfusion abnormalities, such as mapping variably perfused areas and comparing them over minutes to hours, can produce reliable metrics of retinal perfusion that predict SCD severity and mortality better than any currently available clinical biomarker. Using Optical coherence tomography angiography (OCTA) and adaptive optics scanning light ophthalmoscopy (AOSLO) we hypothesize that innovations in retinal imaging may be leveraged to create new biomarkers to guide disease monitoring and improve mechanistic understanding of disease. In our preliminary work, we developed several highly-reliable retinal perfusion metrics, identified 4 mechanisms of small-vessel occlusion in SCD, and showed that one novel perfusion metric, between-session intermittent flow index (IFI), outperformed all current biomarkers as a measure of disease severity and predictor of mortality. We propose to conduct a prospective cohort study using serial retinal imaging and clinical data collection to 1) develop reliable metrics of retinal perfusion (as determined by coefficients of variation and indexes of individuality), 2) validate perfusion metrics as objective indicators of disease severity, treatment response and mortality risk, and 3) compare the mechanisms that cause microvascular occlusion among the 5 major SCD phenotypes. To ensure maximum generalizability and potential for harmonization with other data sources, clinical data will be collected using tools developed from the NHLBI Sickle Cell Implementation Consortium Clinical Data Registry. To accomplish these important goals, the proposed project brings together expertise in ophthalmology, retinal imaging, high- efficiency study design and analyses for rare diseases, stakeholder engagement and SCD.