Ultrasonic transmission in viscoelastic substances

Purpose: To study the propagation of ultrasonic shock waves in viscoelastic agents and the resulting corneal load. Setting: University Siegen, institute for Mechanics and Control Engineering , Siegen, Germany. Methods: The anterior chamber of a manufactured artificial eye was construc ted according to anatomic dimensions. Three openings were drilled-for the p haco lip, for the exchange of a viscoelastic agent or water, and for the sh ock-wave sensor. The sensor was fixed to the area corresponding to the corn eal apex. The sensor signal was analyzed using a direct oscilloscope that m easured the amplitude reaching the corneal apex. Shock-wave propagation in several viscoelastic agents was compared with that in balanced salt solutio n. Results: In hydroxypropyl methylcellulose, the shock wave was amplified or influenced slightly. In hyaluronic-acid preparations, acoustic dampening oc curred. Conclusion: Removal of hyaluronic-acid derivatives prior to phacoemulsifica tion is not necessary. (C) 2000 ASCRS and ESCRS.