Effect Of HIFU On The Histomorphology And Elasticity Change Of Crystalline Lens In Rabbit

Objective： To explore the influence of high intensity focusedultrasound on the histology and elasticity change of rabbit crystalline lensin vitro which has laied a groud work for correcting presbyopia with HIFU.Methods:217freshly enucleated rabbit eyes were randomly dividedinto blank group and HIFU group. The blank group were not radiated withHIFU.The eyes of HIFU group was exposed to HIFU with the acousticpower of1～2W respectively for3s,5s,8s,10s,15s,20s and25s; theacoustic power of3～5W respectively for3s,5s,8s,10s and15s.，to createpattern like4mm circular pipe inside lens tissue.After irradiationmeasuring the long axis and the short axis of bilolgical focal regioninduced by HIFU,then the lens fixed for histology.Based on the studies byFisher,the elastic deformation of the crystalline lens was determinatedbefore and after rotating.Results:1.Gross observation:the irradiation area of the lens had aclear demarcation between surrounding normal tissues.As the outputenergy increases,the biological focal region in lens would be increasegradually.The ratios of the long axis to the short axis of BFR in HIFU were different following therapeutic dosage.2.Histology observation:when HIFUirradiation power were1-5W exposed to3s, morphology of the irraditonarea was regular like the droplet.Their morphology was irregular whenHIFU irradiation power were1-2W exposed to15s and3-5W exposed to8s,seeing lots of cavitation bubble generated by cavitationalmechanisms.The ultrastructural analysis of HIFU radiation of freshlyenucleated rabbit eye lens showed obvious cavitational mechanisms.3.Theirradiation by HIFU could change the elasticity of lens. Multiplecomparison showed that there were no significantly difference in the thedifference radius of anterior curvature、radius of posterior curvature、lensthickness、equatorial diameter and the rate of optical power change of lensbetween blank group,1W、3s and15s group,2W、15s group and3-5W、8s group(P＞0.05).For the remaining groups as compared with the blankgroup there were statistical differences (P <0.05).Conclusions:1.The irradiation area of the lens had a cleardemarcation between surrounding normal tissues,ande as the output energyincreases,the biological focal region in lens would be increasegradually.2.Although rats lens is the most sensitivity to external stimuli andcataracts is extremely easy to form when the lens undergo slight outsidestmuli,the rats lens did not form cataracts with HIFU irradiation.3.WhenHIFU energy was lesser, morphology of the irraditon area was regular likethe droplet and the lens fibers contracted,the main mechanism of action of HIFU was thermal effect.Their morphology was irregular when the energyincreased,seeing lots of cavitation bubble generated by cavitationalmechanisms.4.HIFU irradiation in vitro rabbit lens can be affected theirelasticity change，and in a certain energy cavitation effect could regain theflexibility of the lens.