Femtosecond laser corneal surgery with in situ determination of the laser attenuation and ablation threshold by second harmonic generation

Karsten Plamann; Valeria Nuzzo; Olivier Albert; Gérard A. Mourou; Michèle Savoldelli; Françoise Dagonet; David Donate; Jean-Marc Legeais M.D.

doi:10.1117/12.700646

5 March 2007 Femtosecond laser corneal surgery with in situ determination of the laser attenuation and ablation threshold by second harmonic generation

Karsten Plamann, Valeria Nuzzo, Olivier Albert, Gérard A. Mourou, Michèle Savoldelli, Françoise Dagonet, David Donate, Jean-Marc Legeais M.D.

Author Affiliations +

Proceedings Volume 6426, Ophthalmic Technologies XVII; 642616 (2007) https://doi.org/10.1117/12.700646
Event: SPIE BiOS, 2007, San Jose, California, United States

Abstract

Femtosecond lasers start to be routinely used in refractive eye surgery. Current research focuses on their application to glaucoma and cataract surgery as well as cornea transplant procedures. To avoid unwanted tissue damage during the surgical intervention it is of utmost importance to maintain a working energy just above the ablation threshold and maintain the laser energy at this working point independently of the local and global tissue properties. To quantify the attenuation of the laser power density in the tissue by absorption, scattering and modification of the point spread function we monitor the second harmonic radiation generated in the collagen matrix of the cornea when exposed to ultrashort laser pulses. We use a CPA system with a regenerative amplifier delivering pulses at a wavelength of 1.06 &mgr;m, pulse durations of 400 fs and a maximum energy of 60 &mgr;J. The repetition rate is adjustable from single shot up to 10 kHz. The experiments are performed on human corneas provided by the French Eye bank. To capture the SHG radiation we use a photomultiplier tube connected to a lockin amplifier tuned to the laser repetition rate. The measured data indicates an exponential decay of the laser beam intensity in the volume of the sample and allows for the quantification of the attenuation coefficient and its correlation with the optical properties of the cornea. Complementary analyses were performed on the samples by ultrastructural histology.

Citation Download Citation

Karsten Plamann, Valeria Nuzzo, Olivier Albert, Gérard A. Mourou, Michèle Savoldelli, Françoise Dagonet, David Donate, and Jean-Marc Legeais M.D. "Femtosecond laser corneal surgery with in situ determination of the laser attenuation and ablation threshold by second harmonic generation", Proc. SPIE 6426, Ophthalmic Technologies XVII, 642616 (5 March 2007); https://doi.org/10.1117/12.700646

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