B41-37 The Impact of Idiopathic Pulmonary Fibrosis on Choroidal Vascular Bed Structure

Abstract Rationale To examine the effect of idiopathic pulmonary fibrosis (IPF) on the peripheral vascular bed using spectral-domain optical coherence tomography (SD-OCT) imaging of choroidal vascularization. Methods Using ImageJ/FIJI software, the anatomical features of choroidal thickness and vascular metrics were quantified in 54 participants for Haller’s and non-Haller’s layers in both nasal and temporal regions, 1500 µm central, 5000 µm total and 3500 µm peripheral regions. The analyzed parameters included total choroidal area, choroidal vascularity index (CVI), luminal-to-stromal ratio (LSR), and the relative area and thickness proportions of choroidal sublayers. Statistical evaluations were conducted using t-test, receiver operating characteristic (ROC) analysis, and logistic regression to identify intergroup differences and assess the diagnostic significance of choroidal structural changes. Results We included 27 patients with IPF and 27 age- and gender-matched healthy controls. Among these patients, the mean age at diagnosis of IPF was 71 ± 12 years, with 48% being female. Patients with IPF showed mild impairment in forced vital capacity (median 79% predicted, IQR: 64.00-90.00) and moderate impairment in diffusion capacity for carbon monoxide (median 59.7% predicted, IQR: 54.25-67.78). Haller CVI values in patients with IPF were significantly lower compared to controls in both the 5000 µm total region (60.60 vs. 62.56, p = 0.009) and the 3500 µm peripheral region (60.39 vs. 62.86, p < 0.001). Similarly, Haller LSR values were significantly reduced in patients with IPF in both the 5000 µm total (1.54 vs. 1.69, p < 0.001) and the 3500 µm peripheral (1.53 vs. 1.70, p < 0.001) regions. In contrast, no significant differences were observed between IPF and control groups in the 1500 µm central region for either Haller CVI (62.68 vs. 62.78, p = 0.927) or Haller LSR (1.73 vs. 1.70, p = 0.748). Conclusion This study demonstrates that IPF is associated with distinct alterations in the peripheral choroidal vascular bed, particularly affecting the large vessel (Haller’s) layer. Despite preserved central choroidal structure, patients with IPF exhibited significantly reduced CVI and LSR in the peripheral and total choroidal regions, indicating a loss of vascular component relative to stromal tissue. These findings suggest that systemic microvascular dysfunction in IPF extends beyond the pulmonary circulation, manifesting as peripheral choroidal vascular remodeling. Peripheral SD-OCT-based choroidal metrics, especially Haller’s CVI and LSR, may thus serve as potential noninvasive biomarkers for evaluating systemic vascular alterations in IPF. This abstract is funded by: None