Preferential Sites of Retinal Capillary Occlusion in Sickle Cell Disease

Purpose: To assess the preferential sites of retinal capillary occlusion at the parafovea in patients with sickle cell disease (SCD) using optical coherence tomography angiography (OCT-A).

Methods: OCT-A scans from 107 patients with SCD and 51 race-matched unaffected controls were obtained using a commercial spectral domain-OCT system. At least eight sequential 3 × 3 mm scans centered at the fovea were acquired and averaged for image analysis. In each participant, foveal avascular zone (FAZ) metrics, perivascular, and quadrant-based capillary densities were measured on the averaged full vascular retinal OCT-A slab. Intermittent capillary perfusion at the FAZ border was also identified using sequential registered OCT-A scans.

Results: Perivascular and quadrant-based capillary densities were significantly lower in SCD groups (Kruskal-Wallis tests; P < 0.001) with preferential sites of capillary nonperfusion occurring along periarteriolar aspect of the vascular bed and at the temporal aspect of the fovea. FAZ perimeter and acircularity index were significantly higher in SCD groups (Kruskal-Wallis tests; P ≤ 0.05). However, no significant differences in FAZ area between unaffected control and SCD groups were observed (Kruskal-Wallis test; P = 0.08). The number of capillary segments with intermittent perfusion was higher in the SCD groups.

Conclusions: Our findings suggest that the periarteriolar aspect of the vascular bed is the preferential site of retinal capillary occlusion in patients with SCD with more involvement of the temporal aspect of the parafovea.