Extraction of a Chronically Implanted, Microfabricated, Subretinal Electrode Array

IEEE Trans. Biomed. Eng.

et al. 2011

A miniaturized, hermetically encased, wirelessly operated retinal prosthesis has been developed for preclinical studies in the Yucatan minipig, and includes several design improvements over our previously reported device. The prosthesis attaches conformally to the outside of the eye and electrically drives a microfabricated thin-film polyimide array of sputtered iridium oxide film electrodes. This array is implanted into the subretinal space using a customized ab externo surgical technique. The implanted device includes a hermetic titanium case containing a 15-channel stimulator chip and discrete circuit components. Feedthroughs in the case connect the stimulator chip to secondary power and data receiving coils on the eye and to the electrode array under the retina. Long-term in vitro pulse testing of the electrodes projected a lifetime consistent with typical devices in industry. The final assembly was tested in vitro to verify wireless operation of the system in physiological saline using a custom RF transmitter and primary coils. Stimulation pulse strength, duration, and frequency were programmed wirelessly from a Peripheral Component Interconnect eXtensions for Instrumentation (PXI) computer. Operation of the retinal implant has been verified in two pigs for up to five and a half months by detecting stimulus artifacts generated by the implanted device.

Section: Testing Methodsmentioning

confidence: 99%

A Hermetic Wireless Subretinal Neurostimulator for Vision Prostheses

Kelly

Shire

IEEE Trans. Biomed. Eng.

et al. 2011

“…The retina was first separated from the choroid with a bleb of fluid injected from inside the eye, then the array was inserted into the bleb space. The retina slowly settled on top of the array and held it in place [20], [21]. The placement of the electrode array in the subretinal space took advantage of the eye’s natural forces holding the retina against the choroid.…”

Section: Implant Design Methodsmentioning

confidence: 99%

Communication and control system for a 15-channel hermetic retinal prosthesis

Kelly

Shire

Biomedical Signal Processing and Control

et al. 2011

Self Cite

A small, hermetic, wirelessy-controlled retinal prosthesis has been developed for pre-clinical studies in Yucatan minipigs. The device was attached conformally to the outside of the eye in the socket and received both power and data wirelessly from external sources. Based on the received image data, the prosthesis drove a subretinal thin-film polyimide array of sputtered iridium oxide stimulating electrodes. The implanted device included a hermetic titanium case containing a 15-channel stimulator and receiver chip and discrete circuit components. Feedthroughs in the hermetic case connected the chip to secondary power- and data-receiving coils, which coupled to corresponding external power and data coils driven by power amplifiers. Power was delivered by a 125 KHz carrier, and data were delivered by amplitude shift keying of a 15.5 MHz carrier at 100 Kbps. Stimulation pulse strength, duration and frequency were programmed wirelessly from an external computer system. The final assembly was tested in vitro in physiological saline and in vivo in two minipigs for up to five and a half months by measuring stimulus artifacts generated by the implant’s current drivers.

“…Visual prostheses are being developed by numerous groups around the world as a strategy to restore vision to patients affected by neural forms of blindness. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Each of these approaches seeks to bypass damaged or dysfunctional nerve tissue to deliver visually relevant neural stimulation along surviving visual pathways. [21][22][23][24][25] The most significant challenge for any neurosensory prosthesis is achieving a biocompatible interface in which mechanical and electrochemical damage are minimized to increase the potential for psychophysical benefit.…”

Section: Introductionmentioning

confidence: 99%

Implantation and Extraction of Penetrating Electrode Arrays in Minipig Retinas

Poulaki

Kim

et al. 2020

Trans. Vis. Sci. Tech.

Self Cite

This work was motivated by the goals of demonstrating methods to fabricate and implant large numbers of penetrating arrays into the retina and the feasibility of extraction. Methods: Arrays of inactive, three-dimensional (3D) SU-8 structures were microfabricated onto 13-μm polyimide substrates. Standard vitreoretinal surgical techniques were used with an ab externo approach for subretinal implantation of arrays in 12 mini-pigs. In the first three surgeries, different post-geometries were explored, while a preferred design (128-μm tall, 30-μm diameter, 200-μm spacing) was used for the remaining nine implantations. Two arrays were extracted. Funduscopy, optical coherence tomography (OCT) and immunohistochemistry of the retinae were performed. The unoperated eyes and tissue far from implantation served as controls. A thirteenth pig was implanted with a planar array. Results: Ten implant surgeries had no significant complication, and two arrays were successfully extracted. One retinal tear occurred after implantation due to too long posts in an early surgery. In "successful" cases, OCT showed close apposition of the arrays to the retina and integration of the posts, the tops of which were positioned at the junction of the inner plexiform and ganglion cells, without significant gliosis. Conclusions: These results provide a proof-of-concept that relatively large numbers of 3D posts can be implanted into, and extracted from, the retina of mini-pigs. Our surgical numbers were relatively small, especially for the extractions, and our conclusions must be viewed with that limitation. Our methods are applicable for human surgeries. Translational Relevance: This study provides results of implantation and extraction of relatively large numbers of 3D posts from the retina of minipig eyes. If similar technology were used in humans, a 3D array of this type should lower perceptual thresholds, provide safer long-term stimulation, and perhaps provide better perceptual outcomes.