May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
A Novel Method for Examining the Effects of Electrical Stimulation on the Light Response of Retinal Ganglion Cells
Author Affiliations & Notes
  • E. D. Cohen
    Office of Science and Eng. Labs, Ctr for Dev. and Rad. Health, FDA, Silver Spring, Maryland
  • Footnotes
    Commercial Relationships  E.D. Cohen, None.
  • Footnotes
    Support  FDA
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 5872. doi:https://doi.org/
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      E. D. Cohen; A Novel Method for Examining the Effects of Electrical Stimulation on the Light Response of Retinal Ganglion Cells. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5872. doi: https://doi.org/.

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

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Abstract

Purpose: : To develop a preparation to examine how epiretinal stimulation of the retina by long pulse trains affects normal retinal ganglion cell function.

Methods: : The action potentials of retinal ganglion cells were recorded extracellularly with tungsten electrodes using an in-vitro eyecup preparation of the rabbit retina. Epiretinal electrical stimulation was delivered using a saline-filled optically transparent tube (0.5 mm diam.) over the retinal surface forming the receptive field center. Trains of biphasic (cathodic/anodic) 1msec pulses were delivered to the retina at 50Hz for periods of 1 minute. To assess retinal ganglion cell function, the receptive field center was presented periodically with spot stimuli during the course of the experiment. Pulse train charge densities were tested between 4.4 - 884uC/cm2/phase.

Results: : Low charge density (4.4 -44uC/cm2/phase) pulse trains had little effect on the light-evoked firing of most ganglion cells and there was little impairment of the light-evoked response after train stimulation (6% impaired, n=18 cells; 6% impaired, n=16). However as the charge density of the trains reached 133 uC/cm2/phase, there was often a transient loss of the light-evoked firing in 53% of the cells after train stimulation (n=15 cells). Of those affected, the time to recover the light response averaged 0.54 min. Similar results were seen at 442 uC/cm2/phase; 54% cells impaired (n=13 cells), time of recovery averaged 1.6 minutes. The spontaneous firing rate of the ganglion cell was often reduced for several minutes after pulse train stimulation at 133 or 442uC/cm2/phase. No significant threshold differences were observed for ON- vs OFF-center ganglion cells to epiretinal train stimulation.

Conclusions: : Epiretinal stimulation by high charge density pulse trains for one minute appears to impair local retinal ganglion cell function for short periods which could cause a transient refractory period to phosphene perception in the retinal region below the electrodes. The threshold charge density for observing visual impairment in many cells with long train stimulation was 133uC/cm2/phase.

Keywords: electrophysiology: non-clinical • ganglion cells • pathology: experimental 
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