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 constructed according to anatomic dimensions. Three openings were drilled--for the phaco tip, for the exchange of a viscoelastic agent or water, and for the shock-wave sensor. The sensor was fixed to the area corresponding to the corneal apex. The sensor signal was analyzed using a direct oscilloscope that measured the amplitude reaching the corneal apex. Shock-wave propagation in several viscoelastic agents was compared with that in balanced salt solution.
Results: In hydroxypropyl methylcellulose, the shock wave was amplified or influenced slightly. In hyaluronic-acid preparations, acoustic dampening occurred.
Conclusion: Removal of hyaluronic-acid derivatives prior to phacoemulsification is not necessary.