Measurement and design of refractive corrections using ultrafast laser-induced intra-tissue refractive index shaping in live cats

Daniel R. Brooks, Kaitlin T. Wozniak, Wayne Knox, Jonathan D. Ellis, Krystel R. Huxlin

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


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.

Original languageEnglish (US)
Title of host publicationOphthalmic Technologies XXVIII
EditorsArthur Ho, Per G. Soderberg, Fabrice Manns
ISBN (Electronic)9781510614338
StatePublished - 2018
Event28th Conference on Ophthalmic Technologies - San Francisco, United States
Duration: Jan 27 2018Jan 28 2018

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


Conference28th Conference on Ophthalmic Technologies
Country/TerritoryUnited States
CitySan Francisco


  • Cornea
  • Femtosecond
  • Gradient Index
  • Laser Refractive Correction
  • Multiphoton
  • Vision correction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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