Proceedings of the 17th Iranian Conference of Biomedical Engineering (ICBME2010), 3-4 November 2010 Transforming of images information to the implant part of retinal prosthesis, by convertintg of images to bit formats Shabnam Novin Electrical and Computer Eng. Dept KNT University of Technology Tehran, Iran sh novin@ee.kntu.ac.ir Hamid Abrishami Moghaddam Electrical and Computer Eng. Dept KNT University of Technology Tehran, Iran moghadam@eetd.kntu.ac.ir Amir Masoud Sodagar Electrical and Computer Eng. Dept KNT University of Technology Tehran, Iran amsodagar@kntu.ac.ir Abstract- Much recent research attention has focused on providing a vision substitute to blind people through electrical stimulation of a component of the visual system. This approach is referred to as "visual prosthesis". The device consists of an extra ocular and an intraocular unit. The implantable component receives power and a data signal via a telemetric inductive link between the two units. The extra ocular unit includes a video camera and video processing board and a telemetry protocol encoder chip. The intraocular unit consists of a retinal chip with a telemetry protocol decoder, a stimulus signal generator, and an electrode array. Yet little work on devices that encode visual images into electrical stimuli have been reported to date. [n this paper we focus on the information that should be transformed to the stimulator of electrodes. The idea is to transfer image information to the implant unit, in a "bit by bit" fashion. Keywords-visual prosthesis; image information; pxels; stimulation 1. INTRODUCTION Mobility devices generally provide information for blind people by tactile or auditory methods such as long cane, guide dog and ultrasound based aids. A number of research teams are investigating n altenate approach to provide a vision substitute by electrically stimulating a component of the visual system. This approach is referred to as Artiicial Human Vision (AHV) or a "visual prosthesis". Electrical stimulation can result in the perception of blobs of light in a blind person, called "phosphenes". Currently four locations for electrical stimulation are being investigated: behind the retina (subretinal), in front of the retina (epiretinal), the optic nerve and the visual cortex (using intra and surface electrodes)[l). Two possible approaches for retinal implnts, an epiretinal and a subretinal, have been proposed. In the sub-retinal approach, stimulating electrodes are placed beneath the retina at the location of the retinal photoreceptor layer. In the epiretinal approach the prosthetic device is placed on the surface of the retina to stimulate predominantly the retinal ganglion cell layer[2). Most of the groups work on epiretinal stimulator placed wholly within the ocular anatomy and having power and data sent to this implant via a transcutaneous (or rather a trns-scleral) inductive link[3), Such an architecture has a number of important properties: 1) no wires extend through the eye bounday, reducing the risk of infections and leaving the eye ree to move; 2) the transcutaneous link implant coil is placed close to the ront of the eye, enabling good coupling to the extenal coil, thus facilitating reasonably effective power transfer to the implant; 3) the stimulation appears early in the visual pathway to reduce the required pre-stimulation signal processing[4). A retinal prosthesis system consists of an extenal unit coupled to an implanted stimulator with a wireless link. A video camera in the extenal unit captures an image and converts it to digital data. A programmable image processor then transforms the data into a command signal, which programs the implanted stimulator. The command signal is appropriately coded and transmitted (via telemetry) to the implanted unit. The implanted unit receives the signal, recovers power and data rom the signal, and sets the output of the stimulator. The stimulus patten is applied to the retina via the electrode array. In the present paper we discuss about the information that should be transformed to the stimulator of electrodes. The image is converted into stimulation commands for transmission to the implnted unit. The idea is to transfer image information, in a "bit by bit" fashion. Also, Humayun et al.[5) and Wang et al.[6) describe communication protocol in their prosthesis and discuss about delivering data packets. We describe their work and compare with the present paper in our results. The rest of the paper is organized as follows: Section II summarizes the biology of retina. Section III, discusses the system of implant. Section IV presents the current study. Finally, the results and conclusion are given in section V and VI. II. BIOLOGY OF RETINA Photoreceptors are the specialized neurons in the eye that convert photons into a neural signal (Fig. 1). The photoreceptors are part of the retina, a multilayer neural structure about 200lm thick that lines the back of the eye. 978-1-4244-7484-4/10/$26.00 ©2010 IEEE