Abstract
PURPOSE: Precapillary pulmonary hypertension (PPH) is associated with systemic microvascular remodeling, but the outer retina-choroid relationship remains poorly defined. The aim of this study was to evaluate macular retinal thickness and choroidal structure and to investigate the outer retina-choroid association in patients with catheter-confirmed PPH and healthy controls. METHODS: In this single-center cross-sectional study, 29 patients with PPH defined according to European Society of Cardiology criteria and 37 age- and sex-matched controls underwent enhanced depth imaging spectral-domain optical coherence tomography. Retinal layers were automatically segmented (with manual correction when needed). The Early Treatment Diabetic Retinopathy Study (ETDRS) grid was applied to define measurement subfields. Thickness and volume of the total retina, inner retina, outer nuclear layer (ONL), outer retinal layer (ORL), retinal pigment epithelium (RPE), and choroidal thickness were quantified. Binarized subfoveal scans were used to determine total, luminal, and stromal choroidal areas, and the macular choroidal vascularity index (mCVI). Group comparisons, correlation analyses, ROC curves, and univariate regression models were performed. RESULTS: Compared with controls, patients with PPH demonstrated reduced total macular thickness, ORL thickness, RPE thickness, and central macular choroidal thickness, whereas ONL thickness and mCVI did not differ significantly. In the PPH group, central macular ORL thickness was positively correlated with central macular choroidal thickness and negatively with mCVI (both p ≤ 0.006). Central macular ORL thickness discriminated PPH from controls (AUC 0.818; sensitivity 85.7%; specificity 67.6%). In univariate regression analysis, ORL thickness was significantly associated with choroidal structural parameters (p ≤ 0.007) and bosentan treatment (p = 0.019). CONCLUSION: PPH is associated with thinning of the macular ORL, RPE, and choroid, accompanied by PPH-specific outer retina-choroid structural association absent in controls. ORL thickness may represent an adjunct structural indicator in PPH. These findings are exploratory and require validation in larger, longitudinal cohorts.