Retinal Vascular Findings in Sickle Cell Retinopathy

Sickle cell disease (SCD) is a common inherited blood disease that develops due to hemoglobin (Hb) dot mutation that reduces the oxygen-carrying ability of erythrocytes. In hypoxia, this mutated abnormal Hb causes "sickling" of erythrocytes, and subsequent episodes of hypoxia, acidosis, inflammation, vaso-occlusive crises, and hemolysis cause progressive damage to many organs, including the brain, kidneys, lungs, bones, heart, and eyes. Systemic and ocular findings vary in SCD. Sickle Cell C Disease and Sickle beta-Thalassemia forms of SCD have mild systemic diseases; however, both cause severe ocular diseases. In the posterior segment of the eye, SCD can cause optic neuropathy, retinopathy, maculopathy, and choroidopathy. Retinal vascular findings include tortuosity in retinal vessels, “silver wire” arterioles, angioid streaks, arterial and venous occlusions, arteriovenous anastomoses, and retinal neovascularizations (NVs). Fundus fluorescein angiography (FFA), optical coherence tomography (OCT), and OCT angiography are used in the diagnosis. NVs and the enlargement and irregularity of foveal avascular zone (FAZ) in FFA, macular temporal retinal thinning in OCT, FAZ enlargement, and the reduction in densities of macular capillary in OCT angiography are the main findings. This article is aimed to review the retinal vascular findings encountered in Sickle Cell Retinopathy.