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Technology for sensory impairments (vision and hearing)
Published in Alex Mihailidis, Roger Smith, Rehabilitation Engineering, 2023
J. A. Brabyn, H. Levitt, J.A. Miele
Visual acuity measures resolution for the small central zone of the visual field, but many common eye conditions affect other areas of the field. Retinitis pigmentosa causes a narrowing of the visual field or “tunnel vision,” even though acuity in the center may be quite good for a long time. Glaucoma also causes impairments in the outer or peripheral visual field. A stroke can sometimes cause a “hemianopia,” in which the individual can only see one half (left or right) of the visual field. In age-related macular degeneration, blind spots develop in or near the center of the field but are usually irregular in shape and location. Standard visual field tests may be able to map these “scotomas” crudely but testing by a skilled low vision practitioner can obtain a more accurate assessment of scotoma size, shape, and position.
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
Nanotechnologies and its related micro technologies for vision gives fundamentally restructure the technology and to build up of lesser size and most controlling devices to restore missing visualization and hearing task. The devices gather and make over data and convert light into electrical signals which are send to the human nervous system. Two most prevalent retinal degenerative diseases are retinitis pigmentosa and age-related macular degeneration. Retinitis pigmentosa causes progressive failure of photoreceptors and diminishing peripheral vision. This condition often leads to blindness. The neural wiring from the eye to the brain is still intact, and retinal nerves remain intact and functional, but the eyes lack photoreceptor activity, bridging, and, to stimulate adjacent whole cells, could compensate for photoreceptor loss artificially [32].
Medical device implants for neuromodulation
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
Two devices currently have regulatory approval for the treatment of retinitis pigmentosa. The Argus II Retinal Prosthesis (Second Sight Medical Products, Inc., Sylmar, California) has regulatory approval in Europe and the United States, and the Alpha IMS System (Retina Implant, Reutlingen, Germany) has regulatory approval in Europe. These devices provide patients with partial sight restoration and improvements in daily activities. Patients do not, however, perceive the world as in normal vision. For example, patients often have to move their head or make eye movements across objects to judge what they are viewing. Patients may also experience difficulty in recognizing the details of faces or objects. To improve the performance of retinal prosthetics, improvements are needed in the design of electrode arrays, electronic circuits, and hermetic packaging.
Recent advances in wide field and ultrawide field optical coherence tomography angiography in retinochoroidal pathologies
Published in Expert Review of Medical Devices, 2021
Gagan Kalra, Francesco Pichi, Nitin Kumar Menia, Daraius Shroff, Nopasak Phasukkijwatana, Kanika Aggarwal, Aniruddha Agarwal
The diagnosis of retinitis pigmentosa (RP), a group of diverse clinical entities resulting from a number of genetic defects, is primarily clinical and supported by electrophysiology. In the evaluation of patients with RP, the loss of photoreceptor structure and function can be assessed by various other tools such as adaptive optics imaging, OCT, and microperimetry. However, there has been some interest in determining the extent of retinochoroidal vascular compromise in RP, as this may have an additional bearing on the visual prognosis of patients.
Science and technology of a transformational multifunctional ultrananocrystalline diamond (UNCDTM) coating
Published in Functional Diamond, 2022
Excellent biocompatibility (demonstrated in the application of UNCD coatings for encapsulation of a Si microchip implantable in the eye [69] to restore partial vision to people blind by genetically induced death of photoreceptors (condition known as retinitis pigmentosa). Photoreceptors absorb photons from images outside the eye and transform them into electronic charges injecting into the bipolar cells, which amplify the charges and inject them into the ganglion cells, which transfer the charges to the brain via their axons, to form images (Figure 18 (a)). Photoreceptors can be destroyed by a gene (Figure 18 (b)) [70, 71], leading to the condition known as retinitis pigmentosa, resulting in blindness [70, 71]. The gene does not affect the bipolar and ganglions cells. Auciello participated in a 10-years project (2000-2010) [70, 71], involving physicists, materials scientists, chemists, electronic engineers, medical doctors and surgeons, to develop an artificial retina to restore partial vision to people blind by retinitis pigmentosa. The R&D performed by Auciello’s group focused on developing encapsulation of a Si microchip with UNCD coating to inhibit chemical corrosion of Si by the eye saline humor and enable implantation inside the eye for years. The UNCD coating is the only one that can be used for encapsulating a Si microchip, because is the only one that can be grown at ≤ 400 °C [72, 73], whiting the thermal budget of Si chips, without destroying them. The UNCD-encapsulated Si chip, with large array of integrated electrodes, can be implanted on the retina surface, at the ganglion cell layers (Figure 18 (b)), receiving images from a CCD camera outside the eye, processing the image and injecting electrons on the ganglion cells, which transfer them to the brain through their axons, to form image and return partial vision to blind people. The Si chip is chemically etched by the eye humor. The UNCD coating (Figure 17 (c)) eliminates this problem and enables implantation inside the eye for years (Figure 18 (d)).