In vivo assessment of pharmacologic vitreolysis in rabbits with the digital fluoroscopy system

PURPOSE. The purpose of this study was to demonstrate the efficacy of the digital fluoroscopy system (DFS) for the in vivo assessment of pharmacologically induced posterior vitreous detachment (PVD) and vitreous liquefaction in a rabbit model. METHODS. Twenty eyes from 10 New Zealand white rabbits were divided into 5 groups. In each group, one rabbit received an intravitreal injection of 2.0 U plasmin in the right eye and 0.5 U plasmin in the left eye. Intravitreal injection of 0.1 mL balanced salt solution (BSS) was given in the right eye, and no injection was given in the left eye of another rabbit used as a control. Intraocular fluid dynamics were assessed by the DFS, using a contrast agent in each group at different time intervals (6 hours, 12 hours, 1 day, 3 days, and 7 days). After rabbits were killed, both eyes were enucleated. Scanning electron microscopy was used to confirm the morphological alterations of the vitreoretinal interface as observed in the DFS. RESULTS. Complete PVD was observed after 12 hours with 2.0 U plasmin injection, whereas complete PVD was observed only after 3 days in eyes injected with 0.5 U plasmin. Eyes that received BSS injection or did not receive an injection failed to show complete PVD even after 7 days. Complete vitreous liquefaction was observed after 7 days with 2.0 U plasmin injection, but no eyes with 0.5 U plasmin or BSS injection showed complete liquefaction. We could clearly confirm the presence of PVD and the degree of vitreous liquefaction by using DFS. CONCLUSIONS. Digital fluoroscopy system appears to be a useful tool for the evaluation of pharmacological vitreolysis in rabbits with clear in vivo visualization of PVD and vitreous liquefaction.