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Proceedings Paper

Comparison of transient measurements of infrared radiation and stress waves for practical ablation monitoring during photorefractive keratectomy
Author(s): Miya Ishihara; Tsunenori Arai; Makoto Kikuchi; Hironori Nakano; Satoko Kawauchi; Minoru Obara
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Paper Abstract

We compared infrared radiation measurement with stress wave measurement for real-time ablation monitoring during photorefractive keratectomy (PRK). We estimated temperature elevation which may be one of the most effective parameter for PRK monitoring, because the ablation mechanism is mainly attributed to thermal kinetics. The temperature elevation of ablated cornea was evaluated by the infrared radiation and the stress wave. The thermal radiation from irradiated cornea was detected by a MCT detector. The measured signal increased sharply just after the laser irradiation and decreased quasi- exponentially. We could calculate the temperature elevation by observed signal using Stefan-Boltzmann radiation law. In the case of the gelatin gel (15% wt) ablation in vitro, the temperature elevation was 97 deg. at 208 mJ/cm2 in the laser fluence. We also measured transient stress wave by the acoustic transducer which was made by polyvinylidene fluoride (PVDF) film. The temperature elevation could be calculated from the peak stress amplitude based on the short pulsed laser ablation theory. The good agreement on the temperature elevation was obtained between the infrared and the stress based estimations. Due to non-contact and non-invasive method, our infrared measurements for temperature elevation monitoring may be available to accomplish the feedback control on the PRK.

Paper Details

Date Published: 13 May 1998
PDF: 6 pages
Proc. SPIE 3254, Laser-Tissue Interaction IX, (13 May 1998); doi: 10.1117/12.308179
Show Author Affiliations
Miya Ishihara, National Defense Medical College (Japan)
Tsunenori Arai, National Defense Medical College (Japan)
Makoto Kikuchi, National Defense Medical College (Japan)
Hironori Nakano, Keio Univ. (Japan)
Satoko Kawauchi, Keio Univ. (Japan)
Minoru Obara, Keio Univ. (Japan)

Published in SPIE Proceedings Vol. 3254:
Laser-Tissue Interaction IX
Steven L. Jacques; Jeff Lotz, Editor(s)

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