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Journal of Biomedical Optics • Open Access

Self-focusing and spherical aberrations in corneal tissue during photodisruption by femtosecond laser
Author(s): Valeria Nuzzo; Michèle Savoldelli; Jean-Marc Legeais; Karsten Plamann

Paper Abstract

The use of ultrashort pulse lasers is current in refractive surgery and has recently been extended to corneal grafting (keratoplasty). When performing keratoplasty, however, permanent degradation of the optical properties of the patient's cornea compromises the penetration depth of the laser and the quality of the incisions, therefore causing unwanted secondary effects. Additionally, corneal grafting needs considerably higher penetration depths than refractive surgery. Little data are available about the interaction processes of the femtosecond pulses in the volume of pathological corneas-i.e., in the presence of spherical aberrations and optical scattering. We investigate the influence of the focusing numerical aperture on the laser-tissue interaction. We point out that at low numerical apertures (NAs), tissue damage is produced below and above the focal region. We attribute this phenomenon to nonlinear self-focusing effects. On the other hand, at high NAs, spherical aberrations become significant when focusing at high depths for posterior surgeries, which also limit the cutting efficiency. As high NAs are advisable for reducing unwanted nonlinear effects and ensure accurate cutting, particular attention should be paid to aberration management when developing clinical femtosecond lasers.

Paper Details

Date Published: 1 May 2010
PDF: 8 pages
J. Biomed. Opt. 15(3) 038003 doi: 10.1117/1.3455507
Published in: Journal of Biomedical Optics Volume 15, Issue 3
Show Author Affiliations
Valeria Nuzzo, Harvard School of Engineering and Applied Sciences (United States)
Michèle Savoldelli, Hôpital Hôtel Dieu (France)
Jean-Marc Legeais, Hôpital Hôtel Dieu (France)
Karsten Plamann, Ecole Nationale Supérieure de Techniques Avancées (France)

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