Ultrasound enhanced thrombolysis in experimental retinal vein occlusion in the rabbit.

AIMS To investigate if it was possible to lower the dose of streptokinase and maintain an effective thrombolysis by adding pulsed low energy ultrasound. METHODS 53 retinal veins in 27 rabbits were occluded by rose bengal enhanced laser treatment. Six rabbits were treated with streptokinase (50,000 IU/kg), 10 rabbits were treated with a low dose of streptokinase (25,000 IU/kg), and 11 rabbits were treated with a low dose of streptokinase (25,000 IU/kg) and pulsed ultrasound during 1 hour. Fluorescein angiography was performed immediately before the thrombolytic treatment and after 12 hours. RESULTS In the group treated with streptokinase (50,000 IU/kg) all vessels were open. In the group that was given streptokinase (25,000 IU/kg), 21% of the vessels were open. In the group that was treated with streptokinase (25,000 IU/kg) and ultrasound, 64% of the vessels were open. The difference between groups 2 and 3 is statistically significant (p = 0.011) CONCLUSION Adding pulsed low energy ultrasound makes it possible to lower the dose of streptokinase while maintaining a good thrombolytic effect.