June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Intense ultrashort pulsed light in the infrared selectively damages putative S cones
Author Affiliations & Notes
  • Christina Schwarz
    Center for Visual Science, University of Rochester, Rochester, New York, United States
  • Robin Sharma
    Oculus Research, Redmond, Washington, United States
  • Matthew Keller
    Center for Visual Science, University of Rochester, Rochester, New York, United States
    College of Natural Science, Michigan State University, East Lansing, Michigan, United States
  • David R Williams
    Center for Visual Science, University of Rochester, Rochester, New York, United States
    The Institute of Optics, University of Rochester, Rochester, New York, United States
  • Jennifer J Hunter
    Center for Visual Science, University of Rochester, Rochester, New York, United States
    Flaum Eye Institute, University of Rochester, Rochester, New York, United States
  • Footnotes
    Commercial Relationships   Christina Schwarz, None; Robin Sharma, Oculus Research (E), University of Rochester (P); Matthew Keller, None; David Williams, Canon Inc. (F), Canon Inc. (R), University of Rochester (P); Jennifer Hunter, University of Rochester (P)
  • Footnotes
    Support  Research reported in this publication was supported by the National Eye Institute of the National Institutes of Health under Awards P30 EY001319, R01 EY022371, R01 EY004367, U01 EY025497, and EY007125. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Inst. of Health. This study was also supported by an Unrestricted Grant to the University of Rochester, Department of Ophthalmology from Research to Prevent Blindness, New York, New York, the Beckman-Argyros Award and the Alcon Research Award.
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 4301. doi:
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    • Get Citation

      Christina Schwarz, Robin Sharma, Matthew Keller, David R Williams, Jennifer J Hunter; Intense ultrashort pulsed light in the infrared selectively damages putative S cones. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4301.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Infrared ultrashort pulsed light is used for two-photon excited fluorescence (TPEF) ophthalmoscopy to excite naturally occurring retinal fluorophores such as retinoids and NADH in the ultraviolet. Previously, we have shown that the visual cycle can be tracked at light levels that do not cause detectable damage. However, safety standards are not well established. Here we explore damage thresholds for this pulse regime in the living macaque eye.

Methods : Following dark adaptation, the photoreceptor layer of 3 macaques was exposed at several retinal locations between 2 and 15° eccentricity from the fovea with a 730 nm, 55 fs pulsed laser. Tested retinal radiant exposures were 214, 428, and 856 J/cm2. Reflectance videos and TPEF were recorded simultaneously with an adaptive optics scanning light ophthalmoscope, and the TPEF time course of rods and cones was tracked. Locations were followed up immediately after the exposure and over several weeks.

Results : Only the highest tested exposure (5x ANSI) resulted in detectable changes. During the immediate follow up, a regularly spaced subset of cones emitted ~3x less TPEF and showed an altered TPEF time course. The relative number of affected cones was 11-15%, consistent with the occurrence of S cones in macaque. Over several weeks, the diameter of these cones decreased. Ten weeks after the initial exposure, their space was occupied by cells with the appearance of rods. Other photoreceptors in the exposed area appeared to be unaffected. No changes in structure and TPEF time course were detected when the likelihood of two-photon events was decreased by broadening the pulse duration, while keeping the time-averaged exposure the same.

Conclusions : Retinal exposures to 856 J/cm2 with infrared ultrashort pulsed light can cause selective photoreceptor damage. The density and distribution of the affected cells suggest that they are S cones. While S cones have the lowest sensitivity in the infrared of any receptor class, they are known to be particularly susceptible to ultraviolet and blue light. The effect appears to be due to a multiphoton event and distinct from pure thermal and mechanical mechanisms often associated with ultrashort pulse exposures.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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