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Proceedings Paper

Measurement and design of refractive corrections using ultrafast laser-induced intra-tissue refractive index shaping in live cats
Author(s): Daniel R. Brooks; Kaitlin T. Wozniak; Wayne Knox; Jonathan D. Ellis; Krystel R. Huxlin
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Paper Abstract

Intra-Tissue Refractive Index Shaping (IRIS) uses a 405 nm femtosecond laser focused into the stromal region of the cornea to induce a local refractive index change through multiphoton absorption. This refractive index change can be tailored through scanning of the focal region and variations in laser power to create refractive structures, such as gradient index lenses for visual refractive correction. Previously, IRIS was used to create 2.5 mm wide, square, -1 D cylindrical refractive structures in living cats. In the present work, we first wrote 400 μm wide bars of refractive index change at varying powers in enucleated cat globes using a custom flexure-based scanning system. The cornea and surrounding sclera were then removed and mounted into a wet cell. The induced optical phase change was measured with a Mach- Zehnder Interferometer (MZI), and appeared as fringe displacement, whose magnitude was proportional to the refractive index change. The interferograms produced by the MZI were analyzed with a Fourier Transform based algorithm in order to extract the phase change. This provided a phase change versus laser power calibration, which was then used to design the scanning and laser power distribution required to create -1.5 D cylindrical Fresnel lenses in cat cornea covering an area 6 mm in diameter. This prescription was inscribed into the corneas of one eye each of two living cats, under surgical anesthesia. It was then verified in vivo by contrasting wavefront aberration measurements collected pre- IRIS with those obtained over six months post-IRIS using a Shack-Hartmann wavefront sensor.

Paper Details

Date Published: 8 March 2018
PDF: 15 pages
Proc. SPIE 10474, Ophthalmic Technologies XXVIII, 104741B (8 March 2018); doi: 10.1117/12.2290132
Show Author Affiliations
Daniel R. Brooks, The Institute of Optics, Univ. of Rochester (United States)
Kaitlin T. Wozniak, The Institute of Optics, Univ. of Rochester (United States)
Wayne Knox, The Institute of Optics, Univ. of Rochester (United States)
Univ. of Rochester Medical Ctr. (United States)
Jonathan D. Ellis, The Institute of Optics, Univ. of Rochester (United States)
Univ. of Rochester (United States)
College of Optics Sciences, Univ. of Arizona (United States)
Krystel R. Huxlin, Univ. of Rochester Medical Ctr. (United States)

Published in SPIE Proceedings Vol. 10474:
Ophthalmic Technologies XXVIII
Fabrice Manns; Per G. Söderberg; Arthur Ho, Editor(s)

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