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Visual perception of a hand with a gray-resolution of 8 bits per pixel, generated with the Artificial Vision Simulator software package for a 16 x 16 electrode retinal implant without image enhancement (1 st image); 16 x 16 electrode retinal implant with image (contrast) enhancement (2 nd image); 32 x 32 electrode retinal implant without image enhancement (3 rd image); 32 x 32 electrode retinal implant with image (contrast) enhancement (4 th image).
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Controlled electrical stimulation of the retina can result in visual perception in blind patients. In contrast to the over 100,000,000 photoreceptors in a healthy retina, even hundreds of pixels/electrodes of a retinal implant may restore low-resolution vision for unaided mobility and large print reading. We describe the real-time application of im...
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... Video pixelization to simulate the vision provided by a retinal implant electrode array • Contrast and brightness correction/enhancement • Grayscale histogram equalization for luminance control under severe contrast and brightness conditions • Reduction of available (user-defined) grayscale levels • Edge detection. Fig. 2 shows the visual perception of a hand with a grayresolution of 8 bits per pixel as generated by the Artificial Vision Simulator software package for a patient wearing a 16 x 16 electrode retinal implant with and without image enhancement as well as the four times higher resolved visual perception of the same hand with a 32 x 32 ...
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Crossmodal mappings associate features (such as spatial location) between audition and vision, thereby aiding sensory binding and perceptual accuracy. Previously, it has been unclear whether patients with artificial vision will develop crossmodal mappings despite the low spatial and temporal resolution of their visual perception (particularly in li...
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... This selective electrode activation method reduces the electric crosstalk between electrodes, which induces current dispersion [18], by reducing the number of activated electrodes. (3) As edge detection closely resembles natural retinal visual signal processing [19], visual acuity can be improved using an edge detection method that limits stimulation of electrodes along the edges [20][21][22]. ...
This paper proposes a retinal prosthesis edge detection (RPED) algorithm that can achieve high visual acuity and low power. Retinal prostheses have been used to stimulate retinal tissue by injecting charge via an electrode array, thereby artificially restoring the vision of visually impaired patients. The retinal prosthetic chip, which generates biphasic current pulses, should be located in the foveal area measuring 5 mm × 5 mm. When a high-density stimulation pixel array is realized in a limited area, the distance between the stimulation pixels narrows, resulting in current dispersion and high-power dissipation related to heat generation. Various edge detection methods have been proposed over the past decade to reduce these deleterious effects and achieve high-resolution pixels. However, conventional methods have the disadvantages of high-power consumption and long data processing times because many pixels are activated to detect edges. In this study, we propose a novel RPED algorithm that has a higher visual acuity and less power consumption despite using fewer active pixels than existing techniques. To verify the performance of the devised RPED algorithm, the peak signal-to-noise ratio and structural similarity index map, which evaluates the quantitative numerical value of the image are employed and compared with the Sobel, Canny, and past edge detection algorithms in MATLAB. Finally, we demonstrate the effectiveness of the proposed RPED algorithm using a 1600-pixel retinal stimulation chip fabricated using a 0.35 μm complementary metal-oxide-semiconductor process.
... The psychophysical tests assessed that these photoreceptors could be downsized to hundreds or thousands of individual pixels, such as in 32 x 32 electrode arrays. The basic units of prosthetic vision perception, known as phosphenes, represented by dots or spots of light, can be consistently and reproducibly evoked, allowing the blind person to potentially regain low-resolution vision, enabling them to live normal lives that have always been a distant hope, and perform tasks like unassisted mobility or reading [3], [4]. The retinal prosthesis system mainly consists of two main parts [5]: ...
... The mean shift update iteratively moves each data point x i towards its corresponding local mean m(x i ), as shown Equation 3: ...
... Third is the advancement in technology with the inclusion of CMOS image sensors And finally the other important aspects such as image processing, impedance characterization, device physics, suitable biomaterials, power requirements related to visual prosthesis. However readers are advised to use this review with other recent reviews and articles suggested below for more comprehensive understanding of technology related to visual prosthesis: i) Initial trends in retinal implant like detection of phosphene, placement, elicitation requirement, identification of electrode arrays, impedance values, image processing techniques are shown in [6][7][8][9] ii) Cortical implant technique is discussed in detail in [10,11]. iii) Retinal implant techniques which majorly addresses epiretinal and subretinal implants are discussed in [12][13][14]. ...
... Next task is to process those images effectively via some technique to make the task even easier. Wentai Liu et al. [9] described the real time application of image processing techniques such as histogram equalization, contrast and brightness enhancement, edge detection, gray scale reduction is responsible to enhance the visual perception generated by retinal implants. ...
The objective of visual prosthesis is to develop techniques which can functionally replace the degenerated photoreceptors either by inserting the clinical aid inside the eye or by providing external means. Except AIDS and Cancer, there is hardly any disease than blindness which creates more fear in human's mind. Age-related macular degeneration (AMD) and retinitis pigmentosa (RP) were found to be main cause of vision loss followed by cataract and glaucoma. This paper addresses the journey of visual prosthesis by first highlighting the initial challenges and technical advancement later. We have tactically analyzed the conception of visualization, phosphenes detection and modeling of retina through electrodes which had been the focus of researchers before 1990s. Afterwards with the technological improvement, techniques which could enhance the safety, longevity, biocompatibility, resolution and feasibility were targeted. Categorically visual prosthesis is divided into visual cortex, optic nerve and retinal implantation techniques for restoration of vision in blinds. After analyzing the advantages and shortcomings of all these techniques it is concluded that, retinal implants have been the popular method and adopted as potential way for yielding the artificial vision. Key areas of safety standards, use of new biomaterials for improved resolution and durability, power requirements, image processing techniques, new stimulation methods such as biphasic stimulation, and impact of stimulation current/heat on retinal nerves behavior are also addressed in this paper. With low-cost, lower power consumption and integration technology of CMOS devices, nowadays the CMOS active pixel sensor (CMOS-APS) is the new hope for researchers and clinicians. Analysis of electrode design techniques with microphotodiodes, CCD and now with CMOS-APS suggests that the focus of future research will be in developing the high dynamic range (HDR) pixel that can be directly attached to retina for greater efficiency and resolution.
... Many of the essential components to realize these implantable systems have already been developed and demonstrated, such as actuation and drug delivery [1]- [3] and low power diagnostics [4]- [7]. Existing implementations of communication links in implantable devices are not suitable for many applications due to their poor energy efficiency. ...
... This requires an increase in the data rate, and consequently results in high power consumption [8]. The number of electrodes and encoding resolution in intraocular retinal prostheses are also constrained by the achievable data rate [7]. Applications, such as cochlear implants, retinal visual prostheses, or neural recording would significantly benefit from high data rate communication, and lead to system proliferation. ...
A wirelessly powered 11 uW transceiver for implantable devices has been designed and demonstrated through 35 mm of porcine heart tissue. The prototype was implemented in 65 nm CMOS occupying 1 mm X 1 mm with a 2 mm X 2 mm off-chip antenna. The IC consists of a rectifier, regulator, demodulator, modulator, controller, and sensor interface. The forward link transfers power and data on a 1.32 GHz carrier using low-depth ASK modulation that minimizes impact on power delivery and achieves from 4 to 20 Mbps with 0.3 pJ/bit at 4 Mbps. The backscattering link modulates the antenna impedance with a configurable load for operation in diverse biological environments and achieves up to 2 Mbps at 0.7 pJ/bit. The device supports TDMA, allowing for operation of multiple devices from a single external transceiver.
... For the Gen.-1 external module, images were reduced in resolution and color information and processed based on image histogram classification [43]. The proposed algorithm and other well-known approaches such as Canny's method [48], importance map [49] and hard-thresholding [50] were applied to exemplars of the [44] picture classes in the bank (Fig. 17). The results were then evaluated using questionnaires filled out by a group of randomly selected people. ...
... The image processing on these frames consists of edge detection, edge enhancement, decimation and low-pass filtering [6]. The decimated output image will be a 32 x 32 image thus decimating the original image by a factor of 7.5 x 10[7],[8]. ...
One field where computer-related Image processing technology shows great promise for the future is bionic implants such as Cochlear implants, Retinal implants etc.. Retinal implants are being developed around the world in hopes of restoring useful vision for patients suffering from certain types of diseases like Age-related Macular Degeneration (AMD) and Retinitis Pigmentosa (RP). In these diseases the photoreceptor cells slowly degenerated, leading to blindness. However, many of the inner retinal neurons that transmit signals from the photoreceptors to the brain are preserved to a large extent for a prolonged period of time. The Retinal Prosthesis aims to provide partial vision by electrically activating the remaining cells of the retina. The Epi retinal prosthesis system is composed of two units, extra ocular unit and intraocular implant. The two units are connected by a telemetric inductive link. The Extraocular unit consists of a CCD camera, an image processor, an encoder, and a transmitter built on the eyeglass. High-resolution image from a CCD camera is reduced to lower resolution matching the array of electrodes by image processor, which is then encoded into bit stream. Each electrode in an implant corresponds to one pixel in an image. The bit stream is modulated on a 22 MHz carrier and then transmitted wirelessly to the inside implant. This paper mainly discusses two approaches in image processing which reduces the size of the image without loss of the object detection rate to that of the original image. One is about the related image processing algorithms include image resizing, color erasing, edge enhancement and edge detection. Second one is to generate the saliency map for an image.
... To enhance and optimize the visual perception of retinal implant patients, we have created a comprehensive software package: the Artificial Vision Simulator (AVS) [8,9]. AVS interfaces with standard video cameras and presents the captured video stream in a user-defined pixelation. ...
Simulations of artificial vision suggest that 1000 electrodes may be required to restore vision to individuals with diseases of the outer retina. In order to achieve such an implant, new technology is needed, since the state-of-the-art implantable neural stimulator has at most 22 contacts with neural tissue. Considerable progress has been made towards that goal with the development of image processing, microelectronics, and polymer based MEMS. An image processing system has been realized that is capable of real-time implementation of image decimation and filtering (for example, edge detection). Application specific integrated circuits (ASICs) have been designed and tested to demonstrate closed loop power control and efficient microstimulation. A novel packaging process has been developed that is capable of simultaneously forming communication coils, interconnects, and stimulating electrodes.
... Si la phase de prétraitement de l'image est relativement sommaire dans les dispositifs actuels, de nombreuses études de faisabilité ont été réalisées et de nombreux logiciels destinés à prétraiter l'image de la caméra ont vu le jour. Si certains sont basés sur les outils classiques du traitement de l'image (par exemple Liu et al., 2005), la plupart s'inspirent directement du système visuel humain (Fernandez et al. 2005 ;Eckmiller et al., 2005 ;Zaghloul et Boahen, 2006 ;Asher et al., 2007). Ces approches sont dites biomimétiques. ...
Bien qu'elles existent depuis plus de quarante ans, les prothèses visuelles, qu'elles soient invasives (implants) ou non invasive (systèmes de substitution sensorielle), n'ont pas percé dans le secteur du handicap. Il serait difficile d'imputer cet état de fait à des limitations technologiques. Depuis les premières approches, les prothèses visuelles n'ont cessé de se perfectionner et de se diversifier. Toutefois, si la question de savoir comment transmettre le signal est bien documentée, la question de savoir quel signal transmettre a été plus rarement abordée. Dans cette thèse, nous identifions des outils susceptibles de pousser la conception des dispositifs de suppléance visuelle au-delà de la seule question de l'interface. Nous puisons pour cela dans les développements récents sur les théories actives de la vision et dans les implications de ces théories sur la conception et l'évaluation de dispositifs de perception. Nous nous inspirons par ailleurs du fonctionnement des systèmes perceptifs naturels, et plus particulièrement du traitement de l'information dans le système rétino-cortical humain, dont nous proposons un modèle. Ce modèle, issu de plusieurs travaux de thèse au laboratoire, a fait l'objet d'une simulation logicielle, implémentée dans le dispositif de substitution sensorielle visuo-auditif "TheVIBE". L'impact de ce traitement biomimétique du signal est testé expérimentalement sur des sujets humains équipés du dispositif dans différentes tâches notamment dans une tâche de mobilité en extérieur. L'observation des stratégies mises en oeuvre par les sujets pour se servir du dispositif de substitution permet de formuler de nouvelles hypothèses quant au rôle du traitement du signal dans le processus de vision.
... Several medical methods; medication, photoreceptor implant, stem cell implant, have been used to retina disease. Recently, artificial retina implant has been studied following the development of semiconductor technology [2][3][4][5][6][7]. ...
A key problem of artificial visual prosthesis is the low resolution due to the limited number of electrodes. Various methods such as edge detection, contrast enhancement have been studied as the solutions of the low resolution problem and these methods have been performed to face or object recognition in the close-up image. In this paper, we proposed the region-of-interest detection method using a context-based model, which is appropriate for real situations. The visually-salient region was detected by combining the saliency map with color information. In experiment, to evaluate the proposed model, gaze was estimated using an eye tracker when subjects watch the original image and two types of 10 × 10 pixelized images produced by conventional and saliency based method, respectively. Each gaze of pixelized images was compared with the gaze of the original image. The experiment showed that the gaze using the proposed context based model much more correlates with the gaze of the original image than that of conventional model.
... The entire system consists of the MEMS implant and electronics for telemetry. Several approaches have been developed; most notably, the approach adopted by Sandia National Labs is one in which the electrodes are mounted on flexible springs so that they can be used to stimulate appropriate areas of the retinal surface [113][114][115][116][117][118][119][120][121][122][123][124]. neurons and attempted at optimizing the neuron-electrode interface [125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141]. ...
This paper describes the design, fabrication, and characterization of a microfabricated compartmented culture system (micro-CCS) useful for electrophysiological signaling studies in cultured neurons. The focus of the paper is the process of interfacing the micro-CCS with cultured neurons and to demonstrate the applicability of the system for biochemical-mediated electrophysiological studies. Moreover, we show that we can record action potentials from cultured neurons through the extracellular compartmented application of elevated levels of K(+) ions. Finally, we show that we can isolate the electrophysiological effects of the sodium channel blocker tetrodotoxin in one of the compartments of a two compartment culture while recording electrophysiological data from both compartments.
