September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Investigation into the Short-Term Safety of Localized Re-Treatment of the Retina with a Short Pulse Duration (3-Nanosecond) Laser
Author Affiliations & Notes
  • Glyn Chidlow
    Department of Ophthalmology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
    Department of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
  • Robert James Casson
    Department of Ophthalmology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
    Department of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
  • John P M Wood
    Department of Ophthalmology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
    Department of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
  • Footnotes
    Commercial Relationships   Glyn Chidlow, None; Robert Casson, None; John Wood, None
  • Footnotes
    Support  Research supported through the Innovation Voucher Program, which is a State Government program supporting collaboration between small-medium enterprises and world-class research organisations. 50% of funds were supplied by Dept of State Development, Government of South Australia and 50% by Ellex R&D Pty Ltd.
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 5847. doi:
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    • Get Citation

      Glyn Chidlow, Robert James Casson, John P M Wood; Investigation into the Short-Term Safety of Localized Re-Treatment of the Retina with a Short Pulse Duration (3-Nanosecond) Laser. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5847.

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

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Abstract

Purpose : Subthreshold retinal lasers cause clinically invisible lesions, hence, they could inadvertently be targeted at precisely the same or an overlapping location on re-treatment. Herein, we investigated the safety and cellular responses of repeat laser treatment (whereby lesions were targeted at precisely the same locations on both delivery occassions) using a nanosecond laser (2RT) currently in trials for early AMD.

Methods : Rats were randomly assigned to one of five groups: sham, subthreshold 2RT, subthreshold 2RT re-treatment, visual effect 2RT, visual effect 2RT re-treatment. Re-treatment groups were lasered on day 0 and day 21; single laser groups were only lasered on day 21. All rats were killed at day 28. Analytical endpoints included monitoring of retinal vascular integrity overlying lesions, investigation into any potential choroidal neovascularization, assessment of the RPE, quantification of collateral injury to photoreceptors or other neuronal classes, and delineation of glial reactivity.

Results : Repeat laser administration to rats caused ostensibly identical retinal-RPE-choroid responses to those obtained in age-matched rats that received only a single application. Specifically, by 7 days after treatment, RPE cells were re-populating lesion sites. No obvious consistent differences were evident between the single and repeat laser groups. Moreover, repeat laser caused no (measurable) additive injury to photoreceptors or other retinal neuronal classes from single laser treatment. In re-lasered animals, there was no increase in microglial activity overlying and adjacent to lesion sites relative to single lasered rats. Finally, there was no evidence of choroidal neovascularization after repeat laser treatment.

Conclusions : The overall results provide a measure of confidence that re-treatment of patients with 2RT should not provide any additional risk of developing visual scotomas, choroidal neovascularization, or inflammatory events.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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