Intraocular retinal prosthesis test device

Abstract

-There is a growing interest in the development of a retinal prosthesis device based on a number of recent experiments demonstrating electrical stimulation of retinal tissue with single electrodes. An intraocular retinal prosthesis test device is currently under development at NRL/JHU. The microelectronic device has an image format of 80 X 40 unit cells interfaced to the retinal surface via an array of microwires in a glass matrix. The system architecture and technology development issues are discussed as well as the topic of biocompatibility. This test device will enable acute human experiments in an operating room environment to demonstrate a massively parallel interface between retinal tissue and a microelectronic array. Keywords -Retina, prosthesis, channel glass, multiplexer 1. INTRODUCTION Recent advances in the fields of microelectronics, neurophysiology, and retinal surgery have progressed to the point where an implantable visual prosthesis system, based on electrical stimulation, is now considered feasible. Currently a number of research projects around the world are aimed at developing prosthetic vision systems. The device discussed in this paper addresses the technical problem of positioning a high-density electrode array against the retina to achieve high-resolution retinal stimulation and perception of image sequences in the patient.The outermost layer of the sensory retina consists of photoreceptors; in the macular region, the photoreceptors are mostly cones (color-sensitive). The next layers of the sensory retina are the bipolar, amacrine, horizontal, and the ganglion cells. The axons of the ganglion cells form the optic nerve.Photoreceptor loss from diseases such as retinitis pigmentosa and age-related macular degeneration are the leading causes of legal blindness. Despite near-total loss of photoreceptors, there is relative preservation of the other retinal neurons. By stimulating the remaining functional retinal layers, it may be possible to restore visual perception.Initial experiments with intraocular stimulation, were performed by de Juan and Humayun several years ago [I]. Since that time, a number of research groups have begun the development of retinal prostheses [2,3,4,5,6,7,8]. Some groups are working toward a device that will be implanted on the epiretinal retinal surface while others are developing a subretinal implant.Epiretinal implantation has the advantage of leaving the retina intact by placing the implant in the vitreous cavity, a naturally existing and fluid-filled space. Studies at John Hopkins University Hospital have demonstrated that this array position is biocompatible [9]. Subretinal implantation of a retinal prosthesis essentially replaces the diseased photoreceptors with a microelectronic stimulator device. However, the surgical implantation requires detaching the retina, and the location of the device may be disruptive to the health of the retina.Section 2 gives an overview of the intraocular retinal prosthesis (IRP) concept and associated electrical stimul...

Electrical stimulation of isolated retina with microwire glass electrodes

“…A multiplexer circuit on a silicon chip allows a single line to carry all the image data to be delivered to the retina instead of a dedicated line for each electrode. This is a potential solution that we (Scribner et al, 2001) and others research groups are pursuing (Lagman et al, 2002;Liu et al, 2000). In our design (Scribner et al, 2001) nine additional lines carry power, clock pulses (to shift the image data to each row, column and independent channel) and output data.…”

Recent Advances in Stretchable and Transparent Electronic Materials

“…People have long been inspired by nature, and have made every attempt to re-create the functions of nature, including themselves. In recent years, strides have been made to create artificial muscles, [1][2][3][4][5][6] artificial skins, [7][8][9][10] smart clothing and electronic textiles, [11][12][13][14][15] paper electronics, [16][17][18][19] prosthetic limbs, 20,21 soft and humanoid robots, [22][23][24][25] biomedical devices, [26][27][28][29][30] electronic eyes, 31,32 and flexible and stretchable electronics [33][34][35][36][37] such as transistors [38][39][40] and optoelectronic devices. [41][42][43][44][45] The list goes on; there appears to be no limit to the creativity and utility of these bioinspired inventions.…”

Fabrication of Pillar Shaped Electrode Arrays for Artificial Retinal Implants

“…There have been several efforts to make columnar type electrode arrays for retinal prosthesis, including a gold-sited electrode array connected to rigid multiplexer chip [13], a flexible polyimide-based simple post structure [14], a 3D iridium oxide electrode on a polyimide substrate with post and stacked hat structure [15], a convoluted shaped electrode array [16] and a pillar design for optoelectrical stimulation [17]. In this paper, we present a pillar-shaped electrode array for local stimulation to lower the threshold by decreasing the geometrical distance between stimulating sites and target areas.…”