Dynamic OCT Angiographic Visualization and Quantification of Choriocapillaris Perfusion Fluctuations in Sickle Cell Disease

Abstract

Purpose : Transient vaso-occlusive events play a pivotal role in the progressive manifestation of retinopathy and systemic end-organ complications in sickle cell disease (SCD). This study aims to visualize and measure choriocapillaris (CC) intermittent perfusion in SCD patients using dynamic OCT angiography (OCTA).

Methods : 76 SCD patients (19 HbSC, 48 HbSS and 9 Hb S-Other) and 17 race and age matched unaffected controls were imaged at baseline and 1-hour apart using a clinical SD-OCTA device (Avanti RTVue-XR; Optovue). Ten macula 3x3mm² (304x304pixel²) OCTA scans were obtained and averaged at each session (PMID: 32574351). A 3µm CC OCTA slab located at 27µm below the Bruch’s membrane was extracted (Fig. A & B). Difference of the two CC OCTAs was computed after the correction of image brightness. Percent area of CC intermittent perfusion was defined as any regions with ≥9 pixels on the difference image segmented using Analyze Particles plugin on ImageJ (PMID: 22930834).

Results : Choriocapillaris intermittent perfusion was visualized in all SCD genotypes. Median ± interquartile ranges for intermittent perfusion percent area were .0140±.106; .045±.123; .014±.072; .000±.023 for Hb SC, Hb SS, and Hb S-Other, and unaffected controls, respectively. Statistically significant differences were observed among study groups (Kruskal-Wallis test, p=0.029). Pairwise comparisons showed a statistically significant difference between controls and SCD with HbSS genotype only (p=0.024).

Conclusions : This study demonstrates the novel visualization and quantification of CC intermittent perfusion using clinical OCTA. Our findings of higher percent area in HbSS patients (Fig. C) suggest that monitoring CC intermittent perfusion could be used as a non-invasive indicator of SCD severity and activity.

This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.

 

Averaged choriocapillaris OCTA centered at the fovea in a SCD patient with HbSS genotype. Choriocapillaris OCTA obtained at (A) baseline and (B) 1 hour follow-up. (C) Red (baseline) green (1 hour follow-up) overlay of the two choriocapillaris OCTA images indicates non-perfusion in red and re-perfusion in green.