Experimental Study On Posterior Vitreous Detachment Induced By Tissue Plasminogen Activator Combined With Hyaluronidase In Rabbits

Objective: (1) To create the animal model of posterior vitreous detachment (PVD)induced by intravitreal injection of tissue plasminogen activator (t-PA) combined with hyaluronidase. (2) To detect the effect of PVD induced by different drugs. (3) To evaluate the safety of intravitreal injection of drugs.Methods: Fifteen New Zealand white albino rabbits with the weight of 1.5~2.0kg each were randomly divided into 3 groups with 5 rabbits in each group provided by Animal Center of Tianjin Medical University. The combined drugs of 20IU hyaluronidase and 25g t-PA were injected in eyes of group A, 25g t-PA was injected in eyes of group B, and 20IU hyaluronidase was injected in eyes of group C. Meanwhile, O.lml BSS was injected in control eyes. Pre and postoperative examinations included slit-lamp examination, direct and indirect ophthalmoscopy, electroretinogram (ERG), B-scan, histopathology, and scanning electron microscope (SEM). Conjunctival sac was watered with normal saline under the anesthesia with the injection of chloral hydrate 10% (3ml/kg) in abdominal cavity. Procaine was dropped in the conjunctival sac. Approximately 0.lml vitreous was suctioned from vitreous cavity via pars plana which is 2.5mm posterior to the limbus on the superior temporal side using a 27-gauge needle attached to a tuberculin syringe, and O.lml drug was injected into vitreous cavity. Gentamycin 0.1% eye drops were routinely used three times daily. The rabbits were followedup for 1 week. B-scan examinations were performed preoperatively, 1,3, 9hours, 1,3, and 7days postoperatively. ERG, histopathology, and SEM were performed Tdays postoperatively.Results: (1) The complete PVD were present in eyes of group A Iday postoperatively. (2) The partial PVD were observed in eyes of group B, and PVD was not found in group C and control group 7days postoperatively. (3) There were not any abnormal changes in all eyes of group A, B and C. There was no retinal hemorrhage, exudates, and retinal detachment. The results of ERG, B-scan, and pathology were normal in the tissues.Conclusion: (1) PVD animal model is successfully created by intravitreal injection of t-PA combined with hyaluronidase. (I) The complete PVD can be formed by the intravitreal injection of t-PA combined with hyaluronidase. (3) The uses of these drugs are safe and effective in intravitreal injection.