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Proceedings Paper

Femtosecond laser-induced cavitations in the lens of the human eye
Author(s): Line Kessel; Jose Nymand; Michael Harbst; Mike van der Poel; Lars Eskildsen; Michael Larsen
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Paper Abstract

Ultrafast femtosecond lasers are used increasingly for a wide range of medical purposes. The immediate tissue response to pulses above a certain threshold is optically or laser induced breakdown, which is often visible as gas-filled cavities that persist for some time. In the present study, we attempted to define the cavitation threshold in the human lens in vitro using multiphoton effects based on radiation from a femtosecond 800 nm Ti:Sapphire laser. Cavitations were observed from pulse energy densities exceeding 16 mJ/cm2, but only after several minutes of exposure and not as a result of a single laser pulse. This suggests that cavitations were caused by a process which differs from the single-pulse cavitations observed at higher intensities. To evaluate whether the release of gas was caused by ionization and plasma formation or by thermal effects, we introduced pauses into the pulse train, which did not change the total exposure time needed to form a cavitation. This suggests that local heating did not play a significant role in producing the observed phenomenon, suggesting that photochemical reactions may be involved. These results demonstrate that there are several types of ultrafast laser effects in the lens that have a potential for therapeutic application and treatment of eye disease though further studies are needed to shed light on the nature of the formation of delayed cavitations.

Paper Details

Date Published: 13 July 2007
PDF: 7 pages
Proc. SPIE 6632, Therapeutic Laser Applications and Laser-Tissue Interactions III, 66321H (13 July 2007); doi: 10.1117/12.728021
Show Author Affiliations
Line Kessel, Glostrup Hospital, Univ. of Copenhagen (Denmark)
Jose Nymand, Glostrup Hospital, Univ. of Copenhagen (Denmark)
Michael Harbst, Glostrup Hospital, Univ. of Copenhagen (Denmark)
Mike van der Poel, Technical Univ. of Denmark (Denmark)
Lars Eskildsen, Glostrup Hospital, Univ. of Copenhagen (Denmark)
Technical Univ. of Denmark (Denmark)
Michael Larsen, Glostrup Hospital, Univ. of Copenhagen (Denmark)
National Eye Clinic, Kennedy Institute (Denmark)


Published in SPIE Proceedings Vol. 6632:
Therapeutic Laser Applications and Laser-Tissue Interactions III
Alfred Vogel, Editor(s)

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