The Effect Of Low Intensive Ultrasound On Dexamethasone-Induced Intraocular Hypertension In Rabbit

Objective: To investigate the effect of low intensive ultrasound on dexamethasone-induced intraocular hypertension in rabbit and it initial mechanicsm of its effect. Method: 30 eight-week old New-Zealand rabbit were divided into one normal control group(n=5)and three experiment group(n=25). The latter is applied with 1% Dexamethasone to induce intraocular hypertension model. Then the experiment group were divided into three group in random.In each group , the right eyes were treated with 0.25W/cm2(group A),0.50 W/cm2(group B),0.75 W/cm2(group C),5 minutes,5days. The left eyes were control eyes . The intraocular pressure was monitored. Observe the trabecular meshwork structure by HE staining, ultrastructure by transmission electron microscope, and trabecular meshwork extracellular matrix laminin, fibronectin and collagen I through immunohistochemistry. Result: 1% Dexamethasone can induce intraocular hypertension mode successfully in 8 weeks old rabbit. Its successful rate is 96%. Comparing with the control eye, the IOP of treated eye in group B,C decreased markedly (P<0.05); but the decrease of IOP in group B,C has no difference (P>0.05).Histology observation shows: after treatment, trabecula collagen arrayed in slender bands, interspace was wider than the control eye. The expression of collagenI,laminin and fibronectin was lower in group B,C(P<0.05)than control group ,but group A has no significance. TEM shows in the untreated group, abnormal collagen accumulated in the trabecular meshwork. Trabecula plate was thick, and nucleus was swelling. Conclusion: Rabbit model of intraocular hypertension is suitable for the research on POAG . Proper dosage low-intensity ultrasound can decrease experimental high IOP in rabbit model. The mechanism maybe relate with the change of trabecular meshwork histologic structure and the rarefaction of trabecula by ultrasound oscillating effect .