Abstract
PURPOSE: To characterize microvascular remodeling in retinal vein occlusion (RVO) by distinguishing "congestion" from "compensation" using morphologic decomposition and to evaluate translaminar retina-choroid coupling. METHODS: Swept-source optical coherence tomography angiography was performed on 226 eyes (88 RVO-affected, 88 fellow, 50 healthy controls). Vessel density (VD) was geometrically decomposed into vessel length density (VLD; abundance) and vessel diameter index (VDI; caliber). Linear mixed-effects models were used to account for intereye correlation. RESULTS: In the deep capillary plexus (DCP), fellow eyes exhibited "inefficient compensation" characterized by significantly increased VLD (25.17 ± 4.98 vs. 20.83 ± 4.02 mm/mm²) and decreased VDI (1.42 ± 0.07 vs. 1.47 ± 0.04) compared to controls (P < 0.001). Affected eyes demonstrated "congestive failure" with decreased VLD (16.06 ± 4.84 mm/mm²) and increased VDI (1.51 ± 0.09) (P < 0.05). DCP ischemia was strongly correlated with total retinal thickness (TRT, representing macular edema severity; ρ = -0.43, P < 0.001). A numerical "disease gradient" in retina-choroid coupling (DCP-choroidal vascularity index correlation) was identified: healthy (ρ = 0.37), fellow (ρ = 0.42), and affected eyes (ρ = 0.54). Sensitivity analysis revealed a biphasic synchronization sequence: temporary functional decoupling in mild edema (ρ = 0.30), followed by profound pathologic synchronization in severe congestive disease (TRT ≥400 µm, ρ = 0.63). CONCLUSIONS: RVO is a bilateral, hierarchical disorder. Morphologic decomposition reveals subclinical compensatory remodeling in fellow eyes that is obscured by conventional VD analysis. The progressive synchronization of deep retinal and choroidal degeneration suggests that RVO involves a pathologic collapse of neurovascular autoregulation. TRANSLATIONAL RELEVANCE: Decomposing density into length and diameter provides superior biomarkers for detecting early subclinical changes and monitoring the congestive status of RVO eyes.