Figure 1. Bubbles created within an explanted porcine intraocular lens using laser-induced optical breakdown. The same lens is imaged before and after bubble creation and after bubble collapse using a Siemens SONOLINE Elegra Scanner.
The main goal of this project is to develop a new technology to measure tissue elasticity by deformation with acoustic radiation force applied to femtosecond laser produced microbubbles. First, we will study physical functional relationships by measuring bubble motion in gelatin phantoms with known elastic and viscoelastic properties. Bubbles will be placed in these specimens with photodisruption from a femtosecond pulsed laser so that bubble size and position can be controlled. The bubble is displaced by acoustic radiation force from a high amplitude tone burst originating from one ultrasonic transducer and tracked by a broadband, low amplitude signal from a secondary higher frequency (7.5 MHz) transducer. Relationships between physical parameters, specifically, bubble displacements and displacement time constants, can be used to determine elastic and viscoelastic properties in unknown specimens.
After initial development, the technique will be validated on animal and then human lenses; mapping the spatial variation in these tissues. Preliminary experiments are limited to cadaverous tissues. These results will be helpful for future research with this technique on manipulating lens elasticity for possible presbyopia correction by photodisrupting small areas of tissue in a loosely spaced grid. In another application, with further development of equipment, this technique could be modified to measure elasticity of structures within individual cells.
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