Quantitative Analysis of Retinal and Choroidal Microvascular Changes in Adult IBD Patients: Insights into the Gut–Retina Axis

SOYUTPurpose To quantitatively evaluate retinal and choroidal microvascular alterations in patients with inflammatory bowel disease using optical coherence tomography angiography and to investigate the potential of these parameters as non-invasive biomarkers for the “gut-retina axis.”Methods This prospective, case-control study included 88 patients with inflammatory bowel disease (56 with Crohn’s disease and 32 with ulcerative colitis) and 88 age- and sex-matched healthy controls. All participants underwent 6 × 6 mm macular and 4.5 × 4.5 mm optic disc scans using spectral-domain optical coherence tomography angiography (AngioVue). Key parameters analyzed included vessel density in the superficial and deep capillary plexus, choriocapillaris blood flow area, foveal avascular zone area, and peripapillary retinal nerve fiber layer thickness. Statistical comparisons were performed using independent samples t-tests, Mann-Whitney U, ANOVA, or Kruskal-Wallis tests as appropriate.Results The IBD group exhibited significantly higher parafoveal VD in the SCP (52.85 ± 4.66 vs. 51.57 ± 3.68, p = 0.003) and DCP (56.56 ± 4.26 vs. 52.84 ± 4.07, p < 0.001) compared to controls. CBFA was also significantly increased in IBD patients (p < 0.001). UC patients had higher superficial foveal density than controls and CD patients (p = 0.017). Conversely, CD patients demonstrated a significantly larger FAZ area than UC patients (0.318 vs. 0.234 mm2, p = 0.004). CMT and peripapillary parameters showed no significant differences between groups.Conclusions IBD patients demonstrate increased retinal VD and choroidal flow areas on OCTA, potentially reflecting systemic inflammatory vasodilation. The structural differences between CD and UC suggest OCTA may help explore the gut-retina axis. However, future longitudinal studies adjusting for disease activity and treatments are needed to validate these metrics as clinical biomarkers.