Retinal Intermittent Perfusion and its Associations with Hemolysis in Sickle Cell Disease

Abstract

Purpose : Sickle cell disease (SCD) is characterized by intermittent perfusion and hemolysis, both of which lead to organ damage. This study explores the associations between retinal intermittent perfusion index (IPI) and hemolysis score (HS) in SCD patients.

Methods : 78 SCD patients (19 HbSC, 50 HbSS, 9 HbS) and 45 unaffected controls of race and age matched controls were imaged at two sessions with 1 hour follow-up using a clinical OCT angiography (OCTA) device (Avanti RTVue-XR; Optovue). Ten 3x3mm full vascular layer OCTA scans were obtained at the parafoveal and temporal retina at each session (Figure A & B). Between-session retinal IPI in SCD patients was evaluated using a normative database generated from the unaffected controls (Figure C) (PMID: 34123506). A complete blood count and liver function tests were performed ± 1 week of the date of OCTA imaging for each patient. HS was then derived from standardized log10 of AST, LDH3, total bilirubin, and reticulocyte count.

Results : Median ± interquartile range for HS were -.77±1.06; .33±1.30; and -.81±.95 for HbSC, HbSS, and HbS respectively. Median ± interquartile range for parafoveal IPI (P-IPI) were .28±.41; .71±.95; and .46±.57 for HbSC, HbSS, and HbS respectively. P-IPI, temporal IPI (T- IPI), and the sum of IPIs (S-IPI) all exhibited a positive moderate correlation with HS (Spearman correlation r=.513, r=.512, and r=.568, respectively; p-values<.0001). HS was able to differentiate between SCD genotypes (Kruskal-Wallis p<.0001). Pairwise Comparison HbSC – HbSS p<.0001, HbS – HbSS p=.007

Conclusions : This study sheds light on the correlation between retinal vascular dynamics and hemolytic status in SCD. Higher HS scores are positively correlated with all IPIs, and HS can differentiate between SCD genotypes. This suggests that IPI might be a useful functional indicator of SCD severity.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.