September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Relative power consumption at the electrode-retina interface during retinal stimulation with voltage versus current controlled stimulus pulses
Author Affiliations & Notes
  • Kiran Nimmagadda
    Neuroscience Graduate Program, University of Southern California, Los Angeles, California, United States
    USC - Caltech MD/PhD Program, Los Angeles, California, United States
  • Navya Davuluri
    Biomedical Engineering, University of Southern California, Los Angeles, California, United States
  • James D Weiland
    Ophthalmology, USC, Los Angeles, California, United States
    Biomedical Engineering, University of Southern California, Los Angeles, California, United States
  • Footnotes
    Commercial Relationships   Kiran Nimmagadda, None; Navya Davuluri, None; James Weiland, None
  • Footnotes
    Support  NSF CBET-1343193 and Research to Prevent Blindness
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 3718. doi:
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    • Get Citation

      Kiran Nimmagadda, Navya Davuluri, James D Weiland; Relative power consumption at the electrode-retina interface during retinal stimulation with voltage versus current controlled stimulus pulses. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3718.

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

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Abstract

Purpose : The purpose of this study is to compare power consumed at the electrode-retina interface between rectangular current controlled and voltage controlled stimulus pulses.

Methods : Eleven Long Evans female rats under anesthesia were used for this in-vivo study. A 75 um diameter cylindrical Pt-Ir electrode was inserted into the left eye, and placed 50-100 um from the retina. Charge balanced biphasic voltage-controlled and current-controlled stimulus pulses of varying pulse width and amplitude were delivered to the retina. The pulse widths were 0.3 ms, 0.5 ms, 1 ms, and 2 ms. For each pulse width, voltage and current-controlled pulse trains with charge levels from 10 nC to 60 nC were delivered to the retina. An oscilloscope was used to measure and record the voltage waveform of the stimulus pulses at the electrode-retina interface. A sense resistor in the stimulus current path was used to measure and record the current waveform delivered to the retina. As previously reported, electrically evoked responses (EERs) were recorded from the superior colliculus (SC) in response to the retinal stimulation.

Results : The voltage and current waveforms delivered to the retina were used to measure the power consumed at the electrode-retina interface during the cathodic phase for each stimulus condition. For stimulus pulse widths of 0.3 ms, 0.5 ms, and 1 ms, there was no statistically significant difference between the power consumed by the voltage-controlled pulses versus the current-controlled pulses (student t-test, p > 0.05) at all charge levels tested. For stimulus pulse width of 2 ms, there was no statistically significant difference in the power consumed for stimulus charge levels of 20 nC and 30 nC (student t-test, p > 0.05), while voltage pulses consumed significantly more power than current pulses for charge levels of 40 nC and 50 nC (student t-test, p < 0.05).

Conclusions : In general, there is no significant difference in the power consumed at the electrode-retina interface between voltage and current controlled stimulus pulses, except for long pulse widths like 2ms and charge levels higher than 40 nC. This needs to be taken into consideration in combination with our previously reported results comparing the EERs in response to voltage versus current stimulus pulses when determining the most efficient stimulus parameters for electronic retinal prostheses.

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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