The efficacy of plasminogen-urokinase combination in inducing posterior vitreous detachment.
OBJECTIVE
To investigate the toxicity of intravitreal plasminogen, urokinase, and their combination, and to evaluate their efficacy in the production of posterior vitreous detachment (PVD) in the rabbit eye.


METHODS
Fifty-six albino New Zealand rabbits were examined before and after injection using the indirect ophthalmoscope, slit-lamp biomicroscopy, and electroretinography. Various concentrations of urokinase or recombinant plasminogen or a combination were injected intravitreally into the right eyes of four rabbits for each concentration. The left eyes of the animals served as controls and received 0.1 mL balanced salt solution. Group 1 was injected with pure urokinase (1,000, 5,000, or 10,000 IU); Group 2 with recombinant plasminogen (0.1, 0.4, 1.0, 2.0, 4.0, 8.0, or 16.0 caseinolytic units [CU]); and Group 3 with a combination of 1,000 IU urokinase (highest nontoxic dose) and nontoxic concentrations of plasminogen (0.1, 0.4, 1.0, or 2.0 CU). The animals were killed and the eyes enucleated 15 days after injection. Electron and light microscopy were performed.


RESULTS
A concentration of 1,000 IU of urokinase was found to be nontoxic to the retina. Plasminogen concentrations of 2.0 CU or less did not produce retinal toxicity, whereas 4.0, 8.0, and 16.0 CU of plasminogen caused minimal-to-severe inflammatory response in the vitreous without histologic or electroretinographic changes. Neither plasminogen nor urokinase alone was successful in producing PVD. The combination of 1,000 IU of urokinase and 1.0 to 2.0 CU of plasminogen was effective without causing retinal toxicity.


CONCLUSIONS
Posterior vitreous detachment can be produced in the rabbit eye using a combination of plasminogen and urokinase.
Unal
M
M
LSU Eye Center, Louisiana State University Health Sciences Center School of Medicine, New Orleans, USA.
Peyman
G A
GA
D000818:Animals; D004359:Drug Therapy, Combination; D004596:Electroretinography / Q000187:drug effects; D005343:Fibrinolytic Agents / Q000494:pharmacology* / Q000633:toxicity; D007267:Injections; D010958:Plasminogen / Q000494:pharmacology* / Q000633:toxicity; D010960:Plasminogen Activators / Q000494:pharmacology* / Q000633:toxicity; D011817:Rabbits; D012160:Retina / Q000187:drug effects / Q000473:pathology; D012164:Retinal Diseases / Q000188:drug therapy; D014463:Ultrasonography; D014568:Urokinase-Type Plasminogen Activator / Q000494:pharmacology* / Q000633:toxicity; D014822:Vitreous Body / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology; D020255:Vitreous Detachment / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000473:pathology
D005343:Fibrinolytic Agents; D010958:Plasminogen; D010960:Plasminogen Activators; D014568:Urokinase-Type Plasminogen Activator