Optical coherence tomography angiography as a tool for diagnosis and monitoring of sickle cell related eye disease: a systematic review and meta-analysis.

Sickle cell retinopathy (SCR) is an ocular manifestation of sickle cell disease (SCD). In SCR abnormal sickling of erythrocytes is associated with sight-threatening complications such as neovascularisation, vitreous haemorrhage, maculopathy and retinal detachment. Optical coherence tomography angiography (OCTA) is a novel imaging modality enabling non-invasive assessment of retinal vasculature. This systematic review provides an up-to-date evaluation of the role of OCTA in SCR diagnosis and management. We searched MEDLINE/PubMed, Cumulated Index to Nursing and Allied Health Literature (CINAHL), SCOPUS and Cochrane Central Register of Controlled Trials (CENTRAL) electronic databases. The methodological quality of included studies was evaluated according to the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) recommendations. 31 studies met the inclusion criteria, and 26 suitably complied with the STROBE recommendations. Participant characteristics, including haemoglobin genotype, Goldberg staging, and visual acuity, were reported in twenty-eight (93%), twenty-six (86.6%), and fifteen (50%) studies, respectively. There was no consistent association between OCTA findings and haemoglobin genotype, Goldberg staging or visual acuity. Meta-analysis revealed that foveal avascular zone (FAZ) size and mean vessel density of the superficial and deep capillary plexi were significantly altered in patients with SCR compared to healthy controls. The mean vessel density of the superficial and deep capillary plexus was significantly lower in patients with SCR. OCTA can quantitatively detect retinal vascular remodelling in patients with SCR. Further research should focus on the clinical utility of OCTA for predicting SCR progression and its role in automating SCR staging using machine learning techniques.