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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].
Advances in Neuroprosthetics
Published in Chang S. Nam, Anton Nijholt, Fabien Lotte, Brain–Computer Interfaces Handbook, 2018
While rare, retinitis pigmentosa—a genetically inherited condition that causes progressive loss of vision that leads to blindness as a result of the loss of retinal photoreceptors—is incurable and (other than measures that slow the disease’s progression, such as wearing ultraviolet-blocking sunglasses) untreatable. That said, restoring vision to blind or profoundly vision-impaired patients is an ongoing challenge being pursued by a range of investigations and clinical trials with retinal prostheses, gene therapy, fetal retinal cells, and other protocols. In one such effort, six legally blind retinitis pigmentosa patients received a wireless intraocular retinal implant that stimulated their retinal ganglion cells for 4 weeks. All patients reported having visual sensations—even with low levels of stimulation—and there were no surgical complications (Koch et al. 2008).
Intramolecular π-stacks in mixed-ligand copper(II) complexes formed by heteroaromatic amines and antivirally active acyclic nucleotide analogs carrying a hydroxy-2-(phosphonomethoxy)propyl residue‡
Published in Journal of Coordination Chemistry, 2018
Claudia A. Blindauer, Rolf Griesser, Antonín Holý, Bert P. Operschall, Astrid Sigel, Bin Song, Helmut Sigel
The past two decades have seen enormous progress in antiviral therapies [3, 4], in part triggered by the AIDS pandemic. Among the many new antiviral drugs developed and approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) are the acyclic nucleoside phosphonates (ANPs). The prototype of these ANPs is (S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]adenine (HPMPA; Figure 1 [5–10]) [11]. It has a broad activity spectrum against double-stranded DNA viruses including herpesviruses, adenoviruses, poxviruses, hepadnaviruses, and the cytomegalovirus [4]. HPMPA was never commercialized, but gave rise to three important antivirals that are in clinical use [3, 12, 13]: Cidofovir ((S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine; HPMPC; Figure 1) [14], Adefovir ((9-[2-(phosphonomethoxy)ethyl]adenine, PMEA; Figure 1) [14, 15], and Tenofovir ((R)-9-[2-(phosphonomethoxy)propyl]adenine; PMPA) [16]. Cidofovir (HPMPC) has an activity spectrum similar to that of HPMPA; it was, under the trade name Vistide, in 1997 the first ANP to be approved by FDA and EMA for treatment of cytomegalovirus retinitis in AIDS patients [17]. Besides antiviral activities, antiparasitic [18], and also antiproliferative [19], specifically anticancer [20], activities have been reported for ANPs.
Recent developments in imaging and surgical vision technologies currently available for improving vitreoretinal surgery: a narrative review
Published in Expert Review of Medical Devices, 2023
Elham Sadeghi, Sashwanthi Mohan, Danilo Iannetta, Jay Chhablani
Degenerative retinal diseases and hereditary conditions, such as age-related macular degeneration and retinitis pigmentosa, involve the photoreceptors and may preserve the inner retina, which contains electrically activated ganglion and bipolar cells. Optic nerve prosthesis and thalamic and cortical intracranial stimulation devices were designed to bypass the retina in profound vision loss and provide artificial images. Recently, the retinal prosthesis, which inserts intraocularly, has received lots of attention. This device consists of an imager that converts the light wavelengths to electrical voltage, electronics that process the image and make an electrical pulse, and multiple microelectrodes that transfer the signal to the inner retina [167,168].
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)).