July 2018
Volume 59, Issue 9
Free
ARVO Annual Meeting Abstract  |   July 2018
Evaluation of the safety of laser-delivered Photobiomodulation and its neuroprotection efficacy in a mouse model of Retinitis Pigmentosa
Author Affiliations & Notes
  • Jack Zi Jie Ao
    Ophthalmology and Visual Sciences, University of Adelaide , Adelaide, South Australia, Australia
  • Glyn Chidlow
    Ophthalmology and Visual Sciences, University of Adelaide , Adelaide, South Australia, Australia
  • John PM Wood
    Ophthalmology and Visual Sciences, University of Adelaide , Adelaide, South Australia, Australia
  • Robert J Casson
    Ophthalmology and Visual Sciences, University of Adelaide , Adelaide, South Australia, Australia
  • Footnotes
    Commercial Relationships   Jack Ao, None; Glyn Chidlow, None; John Wood, None; Robert Casson, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 961. doi:https://doi.org/
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      Jack Zi Jie Ao, Glyn Chidlow, John PM Wood, Robert J Casson; Evaluation of the safety of laser-delivered Photobiomodulation and its neuroprotection efficacy in a mouse model of Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2018;59(9):961. doi: https://doi.org/.

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

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Abstract

Purpose : Photobiomodulation (PBM) refers to non-invasive irradiation of a tissue with red/near infrared light. An increasing body of evidence supports the potential for non-coherent, light emitting diode-generated PBM as a therapeutic strategy in neurodegenerative diseases of the retina. Using a slitlamp-mounted, laser-delivered PBM system, we investigated, firstly, the safety of laser-delivered, coherent, PBM in rodent retinas, and secondly, whether such PBM augments cone survival in a mouse model of retinitis pigmentosa.

Methods : Safety study: C57BL/6 mice, pigmented Dark Agouti rats, and albino Sprague-Dawley rats were tested. Eyes received one of the following treatments: (1) control (2) sham (3) 25 mW/cm2 PBM (4) 100 mW/cm2 PBM (5) 500 mW/cm2 PBM. PBM comprised three sessions of 90 seconds of continuous 670 mm laser irradiation (beam diameter 4 mm). Animals were killed at 3 or 7 days after the final session. Optical coherence tomography (OCT) and electroretinogram (ERG) measurements were obtained. Fluorescein angiography (FA) was also conducted. Eyes were taken for histological assessment.
Neuroprotection study: Rd1 mice received sham (n=10), 25 mW/cm2 PBM (n=10), or 100 mW/cm2 PBM (n=11) twice weekly from P21 to P60 in one eye. The fellow eye was untreated (n=31). Optokinetic (OKN) testing was performed at P35. Cone density was quantified on wholemount retinas using antibodies directed against s-opsin and M/L-opsin.

Results : Safety study: there were no significant differences between control, sham, 25 mW/cm2 PBM, or 100 mW/cm2 PBM groups when analysed for the following outcomes: (1) scotopic a- or b-wave ERG amplitudes, (2) retinal parameters as evaluated by OCT, (3) fluorescein angiograms, (4) neuronal counts or glial reactivity. In pigmented, but not albino rats, 500 mW/cm2 PBM caused localized fundus damage in a proportion of animals.
Neuroprotection study: Mice in the 25 mW/cm2 PBM and 100 mW/cm2 PBM groups had significantly higher s-opsin and M/L-opsin counts compared to control and sham groups. PBM also improved optomotor tracking performance in Rd1 mice as compared to control and sham groups.

Conclusions : Laser-delivered PBM was safe at doses up to 100 mW/cm2. Very localized damage occurred at 500 mW/cm2 in occasional pigmented, but not albino retinas. PBM significantly augmented cone survival, as well as improving visual function, in Rd1 mice.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

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