June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Initial Proof-of-Concept of Photoacoustic Neural Stimulation; A Potential Approach to Retinal Stimulation: Preliminary In Vitro Study
Author Affiliations & Notes
  • Peter L Gehlbach
    Ophthalmology, Johns Hopkins Wilmer Eye Inst, Baltimore, Maryland, United States
  • Maged Harraz
    The Johns Hopkins University , Baltimore, Maryland, United States
  • Jin U. Kang
    The Johns Hopkins University, Baltimore, Maryland, United States
  • Jeeun Kang
    The Johns Hopkins University , Baltimore, Maryland, United States
  • Emad Boctor
    The Johns Hopkins University , Baltimore, Maryland, United States
  • Footnotes
    Commercial Relationships   Peter Gehlbach, None; Maged Harraz, None; Jin Kang, None; Jeeun Kang, None; Emad Boctor, None
  • Footnotes
    Support  NONE
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 5886. doi:
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      Peter L Gehlbach, Maged Harraz, Jin U. Kang, Jeeun Kang, Emad Boctor; Initial Proof-of-Concept of Photoacoustic Neural Stimulation; A Potential Approach to Retinal Stimulation: Preliminary In Vitro Study. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5886.

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

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Abstract

Purpose : There is prior work to provide “virtual vision” for blind patients via electrical or ultrasonic stimulation. Here we propose initial proof-of-concept for a novel photoacoustic neuromodulation (PANM) approach. This in vitro study, indicate predicted neural responses that suggest a potentially promising approach for eventual stimulation of retinal neurons in blind patients.

Methods : For this preliminary proof-of-concept study, the experimental procedures consists of three steps: 1) localized excitation using a pulsed laser delivery to an absorptive material placed under the plate containing neurons, 2) cell stimulation by photoacoustic pressure, and 3) fluorescence quantification of the resulting change in membrane potential. A plate harboring hippocampal neuronal cells was situated above the absorptive media which generates the photoacoustic pressure by the laser excitation using 1064-nm fiber-coupled laser with 1mJ energy per pulse (redENERGY G4-20W-Z type, SPI Lasers UK Ltd., United Kingdom). The membrane potential change of neurons loaded with a fast-acting membrane potential sensitive fluorescent dye (FLIPR) was monitored over 300 seconds. The PANM was performed for 5 seconds at the 60-second time point with at varying pulse repetition rates, i.e., 1kHz and 2kHz. Identically treated sham animals received no PANM. . The membrane potential change was normalized at 10 seconds in each case.

Results : The sham and PANM groups had comparable membrane potentials at the 60-second time point (prior to PANM), i.e., 1.07 ± 0.02 and 1.05 ± 0.02, respectively. However, at 300 seconds, the membrane potential change in PANM treated groups showed a statistically significant and dose dependent increase in depolarization; PANM treated groups at 1 kHz and 2 kHz PRF respectively, equal 1.3 ± 0.05 and 1.53 ± 0.44 as compared to shams at 1.21 ± 0.06. While there is baseline drift in the sham the change between PANM treated groups was significant.

Conclusions : Based on these preliminary findings, we are investigating the potential for photoacoustic retinal stimulation as a potential strategy to achieve virtual vision in blind patients.

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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