Acute electrical stimulation of the human retina with an epiretinal electrode array

Abstract

. Purpose: To determine the threshold charges needed for eliciting visual perceptions through acute electrical stimulation of the human retina in patients suffering from retinitis pigmentosa, using an epiretinal microelectrode array. Methods: In a multicentre study, 20 patients (average age 55 years) with visual acuities ranging from 4/200 to no light perception were included. The stimulation procedure was performed during a pars plana vitrectomy, for a maximum of 45 min, by using a microcontact film with IrOx electrodes connected by cable to a current generator. After repeated stimulation and threshold charge determination, the microelectrode array was removed. Results: Nineteen of 20 patients stated in the postoperative interviews that they experienced one or more visual perceptions with close time correlation to single stimulation events. Minimum threshold charges needed to generate visual perceptions could be measured and verified in 15 patients. The charge level ranged from 20 to 768 nC with single or multiple electrodes. One patient suffered a retinal detachment during the procedure; this patient’s retina was successfully reattached. There were no further adverse reactions observed during the 3‐month follow‐up. Conclusion: Acute epiretinal stimulation of the human retina, using a microelectrode array, can elicit visual perceptions in blind patients with retinitis pigmentosa.

A Treatise of the Physical Aspects of Phosphenes and Single-Cell Selectivity in Retinal Stimulation

“…Figure 1(a) shows an example of the activation area related to the flexible film electrode carrier developed by Keserü et al, [15]. In this example, an array of active electrodes injects charge density to trigger a response of some ganglion cells.…”

“…Humayun et al, [6][7][8][9], Mahadevappa et al, [10], Rizzo III et al, [11,12], Klauke et al, [13], Eger et al, [14] and Keserüet al, [15] and recent clinical trials [16,17] have reported that blind patients perceived sensations of spots of light while the retina was electrically stimulated. These experiments clearly validated the viability of producing perception of light patterns in blind patients by electrically activating nearby retinal ganglion cells (RGCs).…”

“…These experiments clearly validated the viability of producing perception of light patterns in blind patients by electrically activating nearby retinal ganglion cells (RGCs). In recent years, Humayun et al, [7,9], Keserü et al, [15], Dobelle et al, [18,19], Zrenner et al, [20,21], Brindley et al, [22,23] and Hornig et al, [24] have reported the generation of recognizable symbols and simpleshapes from multiple stimulated phosphenes.…”

“…In recent years, epi-and subretinal implants have been developed [6][7][8][9][10][11][12][13][14][15]. Humayun et al, [6][7][8][9], Mahadevappa et al, [10], Rizzo III et al, [11,12], Klauke et al, [13], Eger et al, [14] and Keserüet al, [15] and recent clinical trials [16,17] have reported that blind patients perceived sensations of spots of light while the retina was electrically stimulated.…”

“…A phosphene is defined as any visual sensation represented as a spot of light in the visual field caused by methods other than stimulation of the visual system by light. Phosphenes can be elicited by mechanical forces [2], magnetic stimulation [3][4][5] or electrical stimulation [6][7][8][9][10][11][12][13][14][15].…”