An Experimental Study About The Ultrasound Parameters For Delivering Drugs Into Rabbit’s Vitreous Using Ultrasound Combined With Microbubble

ObjectiveTo screen proper ultrasound parameters for delivering drugs into rabbit’s vitreous usingUltrasound combined with microbubble.MethodsThirty-six healthy New Zealand white rabbits were divided into blank control group (n=3),experimental control group (n=6) and experimental group (n=27). The experimental controlgroup were further divided into2subgroups: one was treated with ultrasonic irradiation only（ultrasonic intensity of2.0W/cm2+irradiation time of120s）and the other with intravitrealinjection of0.1ml microbubbles only (n=3for each subgroup). The experimental group wasfurther divided into nine subgroups which were treated with ultrasonic irradiation of0.5W/cm2、1.0W/cm2、2.0W/cm2in ultrasonic intensity, in a combination with30s、60s、120s in irradiationtime, respectively. After treatment, retina was dissecting from all above groups. Tissuemorphology was measured using light microscopy and cell apoptosis by the method ofTUNEL.Results1. Compared with the blank control group， there were no significant changes in theexperimental control group, the experimental group1and2. Specifically, no abnormalitieswere found in the HE staining tissue. Every layer in the retina was complete and regular. Therod and cone cell layer were intact and arranged in neat. The inner nuclear layer (INL) andouter nuclear layer (ONL) were clearly seen and arranged regularly. The amount and themorphology of retinal ganglion cells were normal as well.2. Compared with the blank control group, varying degrees of impairment in every retinal layerwere found in the experimental group3，4，5,，6，7，8，9.3. In the apoptosis analysis, there were no brownish cells (apoptotic cells) found in the retina ofthe experimental control group, the experimental group1and2, in comparison to blankcontrol group. The structure of the retina in these groups was also as regular as that in theblack control group4. In contrast, a few apoptotic cells were observed in ONL in the experimental group3,4,5,6. 5. A high proportion of apoptotic cells were detected in ONL in the experimental group7，8，9. The structure of the retina in these groups was obscure and irregular, compared with theblank control group.ConclusionOur prelimary results showed that ultrasonic irradiation with0.5W/cm2in intensity, incombination with30s or60s in duration, were safe to the retina in rabbits. Thus, these findingsoffer useful data for delievering neuro-protection drugs for glaucoma animal models, based ontechniques of ultrasound and microbubble.