Relating retinal blood flow and vessel morphology in sickle cell retinopathy

Purpose The purpose of the current study was to determine associations between retinal blood flow and vessel morphology metrics in sickle cell retinopathy (SCR) and healthy normal control (NC) subjects. Methods Optical coherence tomography angiography (OCTA) and Doppler OCT imaging were performed in 12 SCR (15 eyes) and 19 NC (26 eyes) subjects. Vessel tortuosity was measured using a dedicated image analysis algorithm applied to OCTA images. Vessel density and spacing between vessels were determined from OCTA images by a fractal dimension analysis method. Retinal blood flow was quantified using a phase-resolved technique applied to en face Doppler OCT images. Results There was a significant association between increased retinal blood flow and increased vessel tortuosity ( P = 0.03). Furthermore, increased retinal blood flow was associated with increased vessel density ( P = 0.03) and decreased spacing between small vessels ( P = 0.01). There was no significant association between retinal blood flow and spacing between large vessels ( P = 0.11). Vessel tortuosity and blood flow were increased, whereas spacing between small vessels was decreased in SCR compared to NC group ( P ≤ 0.03). There were no significant differences in vessel density or spacing between large vessels between the SCR and NC groups ( P ≥ 0.31). Conclusions Associations between retinal hemodynamics and vessel morphology were reported, providing better understanding of retinal pathophysiology and insight into potential quantitative biomarkers to evaluate SCR.