Associations of Retinal Vascular Morphology and Inflammatory Bowel Disease: A cross-sectional analysis.

Abstract

Purpose : Inflammatory bowel disease is a systemic inflammatory disorder that is classified as Crohn’s disease (CD) or ulcerative colitis (UC). In addition to gastrointestinal manifestations, IBD can have extraintestinal paraphernalia including ocular involvement. Previous studies have alluded to links between IBD and abnormalities in retinal vasculature, including changes in the fractal dimension (FD). The aim of this study was to determine any associations between IBD and retinal vascular FD.

Methods : This was a cross-sectional analysis of data from the ‘AlzEye’ study, a retrospective cohort of 154,830 patients, aged ≥ 40 years, who had retinal imaging at Moorfields Eye Hospital, between 2008 and 2018. Retinal vascular FD were extracted from macula-centered color fundus photographs using ‘Automorph’, an in-house developed deep-learning algorithm. The data was curated based on image quality and missing features. Wilcoxon testing and linear regression modeling were used to assess the association between vascular indices and IBD.

Results : Within the AlzEye study, there were 736 patients with IBD and 90,355 control subjects (mean age 71.7 ± 11.4 years, 53.8% male). Overall, patients with IBD had a reduced mean FD of 1.466 (0.05 SD), while those without IBD had a mean FD of 1.472 (0.05 SD), p-value<0.001. Crohn’s (n=246) specifically had a mean FD value of 1.468 (0.05 SD) vs UC (n=523) which had a mean FD value of 1.463 (0.05 SD). When stratified for diabetes mellitus status, similar trends were observed for FD in patients without diabetes (p-value<0.001), but not in those with diabetes (p-value 0.13). Linear regression modeling to control for age, gender, ethnicity, diabetes and hypertension gave rise to an adjusted estimate of 0.00374 for FD in the IBD cohort (p-value<0.001).

Conclusions : This study sheds light on the association of IBD with reduced retinal vascular fractal dimension. In patients with concomitant diabetes, meaningful conclusions could not be drawn. Although our work illustrates quantifiable differences in retinal morphology in individuals with IBD, further research is warranted to determine the clinical significance and their potential utility as an adjunct outcome measure for disease progression and response to therapy.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1: Heat map depicting retinal morphology features associated with IBD. White triangles denote statistically significant results.