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Recent Developments in Nanomaterial Applications
Published in B. Sridhar Babu, Kaushik Kumar, Nanomaterials and Nanocomposites, 2021
S. Saravanan, E. Kayalvizhi Nangai, S. V. Ajantha, S. Sankar
Retinal implants are devices that are designed to restore vision. They stimulate functional neurons in the retina electrically to restore vision. The artificial retina devices are provided with tiny camera fixed in eyeglasses which confine visual pictures and air sends the message to a microcomputer wear on a belt and transmits it to receiver on the eye. Optobionics create chip which is inserted behind the retina and designed to substitute photoreceptors in the retina. Retinal implant devices initiate electrical simulation and than to light stimulation, so that the visual system is activated and it can significantly improve their quality of life [33].
Journey of Visual Prosthesis with Progressive Development of Electrode Design Techniques and Experience with CMOS Image Sensors: A Review
Published in IETE Journal of Research, 2018
This review addresses four major areas of visual prosthesis: the first is the understanding the problem of vision loss and the initial trials. Second is the subsequent progress in the development of electrode design including all the approaches of visual cortex, retinal implants and optic nerve implants. Third is the advancement in technology with the inclusion of CMOS image sensors Finally, the fourth is 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: Initial trends in retinal implant like detection of phosphene, placement, elicitation requirement, identification of electrode arrays, impedance values, image processing techniques are shown in [6–9].Cortical implant technique is discussed in detail in [10,11].Retinal implant techniques which majorly addresses epiretinal and subretinal implants are discussed in [12–14].Introduction of CMOS image sensors and its experience in the journey of visual prosthesis is covered in [15–18].However, general studies covering all the aspects listed above can be found in [19–29], which basically emphasize on need of visual prosthesis, successful implants, results and future challenges.Before understanding the fundamentals of visual prosthesis, it is first important to understand the functioning of eye and related disease. Figure 1 shows the internal structure of eye. Vision is actually the result of the outstanding neuroprocessor called retina which is responsible in receiving and processing the tremendous complex information with its neuroepithelium sensor. Retinal implant technique is based on elicitation of nerves through electrical signal which is done inside the retina with the help of rods and cones. They actually convert the chromatic and achromatic color images with the help of 130 million photoreceptor cells with 1.2 million retinal ganglion cells (RGC) into chemical and electrical signal exploring the spatial and temporal resolution. Finally geniculation muscles take this electrical information to the cortex of the brain and human see the image [2,21].