Background: The aim of this study was to analyze and compare intravitreal activity and concentrations of different components of the fibrinolytic cascade in eyes with central retinal vein occlusion (CRVO) as well as branch RVO (BRVO) and healthy controls. These results were correlated with corresponding intravitreal vascular endothelial growth factor (VEGF) concentrations as a biomarker for the severity of blood-retina barrier (BRB) breakdown.
Material and methods: Vitreous samples were obtained from 14 eyes with CRVO, 22 eyes with BRVO and 11 controls and the activities and concentrations of plasminogen, plasmin-alpha2-antiplasmin (PAP) and VEGF were analyzed.
Results: Intravitreal activities and concentrations in the CRVO, BRVO and control groups were 2.07 ± 1.87%, 1.24 ± 1.12% and 0.38 ± 0.63% for functional plasminogen, 8.14 ± 7.07 ng/ml, 6.96 ± 4.8 ng/ml and 9.74 ± 10.98 ng/ml for PAP while respective results for VEG levels were 1269 ± 1318 pg/ml, 528 ± 543 pg/ml and 105 ± 116 pg/ml, respectively. There were significant differences in intravitreal functional plasminogen and VEGF between the groups analyzed (in each case p < 0.001). Intravitreal functional plasminogen correlated with intravitreal VEGF concentrations (r = 0.478, p = 0.001). No adverse events or serious side effects occurred.
Conclusion: There were significant differences in intravitreal functional plasminogen and VEGF between eyes with CRVO, BRVO and controls. Intravitreal activity of plasminogen was significantly correlated with the severity of BRB breakdown in RVO affected eyes. The knowledge of intravitreal activities and concentrations of different components of the fibrinolytic cascade could offer new therapeutic strategies in RVO-affected eyes in the future.