Increase in efficacy of near-infrared laser induced refractive index change (LIRIC) in corneal tissue with sodium fluorescein and riboflavin: comparison of two repetition rates

Sara M. G. Campaign; Wayne H. Knox

doi:10.1117/12.2546418

2 March 2020 Increase in efficacy of near-infrared laser induced refractive index change (LIRIC) in corneal tissue with sodium fluorescein and riboflavin: comparison of two repetition rates

Sara M. G. Campaign, Wayne H. Knox

Author Affiliations +

Proceedings Volume 11270, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XX; 1127005 (2020) https://doi.org/10.1117/12.2546418
Event: SPIE LASE, 2020, San Francisco, California, United States

Abstract

LIRIC (laser induced refractive index change) employs femtosecond laser pulses to inscribe local refractive index (RI) changes in corneal tissue via multi-photon absorption. Using a near-infrared wavelength (810 nm) offers a decreased risk of photochemical damage to the retina for clinical applications of LIRIC for refractive vision correction compared to shorter wavelengths that have been used, however the multi-photon order is higher, limiting the amount of RI change achievable before damage. Excised rabbit corneal tissue samples were soaked in 0.25% and 0.50% solutions of either riboflavin or sodium fluorescein, photosensitizers with large two-photon absorption cross-sections at 810 nm that are biologically compatible and safe for use in the cornea. Near-infrared LIRIC was performed on these doped cornea samples as well as on undoped samples using two different laser sources: a Ytterbium fiber laser at 5 MHz and a Ti:Sapphire oscillator at 80 MHz, with average powers in the laser focal volume up to 140 mW and 950 mW, respectively. For the native cornea, similar RI change was induced at both repetition rates for a scanning speed of 10 mm/s (5 MHz) and 20 mm/s (80 MHz). Doping the cornea with either sodium fluorescein or riboflavin allowed for a 10x increase in scanning speed at 5 MHz and a 5x increase in scanning speed at 80 MHz while producing a similar magnitude of RI change to that of the native cornea. With all samples, using the lower repetition rate allowed for a large reduction in the average power needed to induce a similar amount of RI change.

Conference Presentation

Citation Download Citation

Sara M. G. Campaign and Wayne H. Knox "Increase in efficacy of near-infrared laser induced refractive index change (LIRIC) in corneal tissue with sodium fluorescein and riboflavin: comparison of two repetition rates", Proc. SPIE 11270, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XX, 1127005 (2 March 2020); https://doi.org/10.1117/12.2546418

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