Purpose:
To study the potential efficacy of ultrasound (US)-assisted microbubble (MB) destruction as an innovative thrombolytic tool for the treatment of retinal vein occlusion (RVO).
Methods:
Experimental RVO in the right eyes of 40 rabbits was induced using laser photothrombosis followed 48 hs later by the US experiment. Rabbits were randomly divided into 4 equal groups: US+MB group, US+saline group, MB+sham US group, and no treatment group. The last 3 groups acted as control. Fluorescein fundus angiography (FFA) and pulse Doppler US were used to evaluate the retinal blood flow. Pulse Doppler measurements were represented as mean ± SD and one-way ANOVA test was used to compare means. Statistical significance was defined as P <0.05.
Results:
MB-assisted US thrombolysis resulted in restoration of flow in 70% of rabbits. (Fig.1) None of the control groups showed significant restoration of retinal venous blood flow. The mean venous blood velocity for the US+MB group improved from 0.05±0.1 cm/s before the experiment to 1.28±0.9 cm/s at the end of the experiment with a statistically significant difference (p value = 0.002). On the other hand, the final measurements of retinal venous blood velocity for the 3 control groups were not statistically different from the baseline i.e. postlaser measurements. (Fig.2) Pulse Doppler US measurement of the retinal blood velocity in retinal vessels correlated well with the FFA results.
Conclusions:
US-assisted thrombolysis using non-targeted contrast agents is a promising therapeutic tool for RVO and may serve as a new, noninvasive intervention for RVO in humans.
Keywords: vascular occlusion/vascular occlusive disease • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina