Professor Denise M. Krol
Department of Applied Science
UNIVERSITY OF CALIFORNIA, DAVIS
 
Ultrafast (fs) lasers are becoming increasingly important in a number of areas of laser eye surgery. In all these applications the fs laser is solely used as a cutting tool and tissue effects involve laser induced optical breakdown followed by plasma formation and the generation of cavitation bubbles. In inanimate materials such as glasses and crystals ultrashort laser pulses can give rise to similar effects. However, extensive studies on fs laser-matter interaction in these materials have shown that the characteristics of the laser-induced changes depend very strongly on the laser parameters involved. There is a regime of laser conditions in which it is possible to modify the refractive index of materials within the focal region of the laser beam with micron-size precision and without damaging the optical quality or structural integrity of the material. Our long-term goal is to investigate whether it is possible to use fs lasers to induce permanent changes in the refractive index of the cornea without compromising its transparency. This would allow for vision correction without the need for a surgical procedure.

In order to determine changes in the cornea that are more subtle than those associated with tissue removal or cutting it is necessary to use diagnostic tools that are able to reveal changes in the organization and internal structure of the collagen fibrils (and water) of which the corneal stroma is made up. In this talk I will discuss how a combination of confocal microscopy techniques, such as second-harmonic generation (SHG), fluorescence and Raman microscopy can be used to determine the changes in corneal tissue after fs laser exposure.

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