Association of Retinal Microvascular Density with Hemodynamic and Clinical Severity Markers in Pulmonary Arterial Hypertension

PURPOSE: To evaluate whether quantitative retinal microvascular and structural parameters, measured by optical coherence tomography angiography (OCTA), are associated with disease severity and right ventriculo-arterial coupling in patients with pulmonary arterial hypertension (PAH). METHODS: This cross-sectional study included 45 patients with confirmed PAH, stratified by New York Heart Association (NYHA) functional class (I-III). Patients with coexisting ocular pathologies were strictly excluded. Vessel density (VD) in the superficial (SCP) and deep capillary plexuses (DCP), foveal avascular zone characteristics, and ganglion cell complex (GCC) thickness were analyzed. These parameters were correlated with functional capacity (6-minute walk test [6-mWT]), NT-proBNP levels, and the echocardiographic TAPSE/sPAP ratio. RESULTS: Retinal VD in both SCP and DCP progressively decreased with worsening NYHA functional class (p < 0.05). Retinal VD showed a significant negative correlation with NT-proBNP levels (r = -0.355, p = 0.017) and a positive correlation with 6-mWT distance (r = 0.499, p < 0.001). Crucially, retinal microvascular density demonstrated a robust positive correlation with the TAPSE/sPAP ratio (r = 0.420, p = 0.004), a surrogate for right ventriculo-arterial coupling. GCC thickness exhibited variations across NYHA classes but lacked a consistent linear progression. CONCLUSION: Retinal microvascular attenuation in PAH is strongly associated not only with functional and biochemical severity but also with central hemodynamic impairment represented by the TAPSE/sPAP ratio. These findings suggest that OCTA-derived vessel density may serve as a promising, non-invasive biomarker for monitoring systemic microvascular compromise and right heart function in PAH.