OSLI Retina

October 2018

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742 Ophthalmic Surgery, Lasers & Imaging Retina | Healio.com/OSLIRetina Practical Retina Incorporating current trials and technology into clinical practice Practical Concepts With the Argus II Retinal Prosthesis by Paul Hahn, MD, PhD There are revolutionary advances in surgery — radical shifts that change the trajectory of a field — and evo- lutionary changes, or more incremen- tal advances. The introduction of the Argus II reti- nal prosthesis was clearly a revolu- tionary change and earned its primary inventor, Mark S. Humayun, MD, PhD, of USC, the Unit- ed States National Medal of Technol- ogy and Innovation in 2016. The Argus II, named after Argus Panoptes, the all-seeing giant with 100 eyes from Greek mythology, has been termed the "bionic retina" by the lay press. The Argus II received U.S. Food and Drug Administration approval as a humanitarian use device for patients who have bare light perception or no light perception vision secondary to retinitis pigmentosa. In this installment of Practical Retina, Paul Hahn, MD, PhD, from NJ Retina shares his significant expe- rience in implanting the Argus II. He explains the importance of careful pa- tient selection, setting appropriate pa- tient expectations, and the rehabilita- tive process required postoperatively. Dr. Hahn provides surgical pearls for the various steps of the implantation procedure. Artificial vision will hopefully be- come a burgeoning field, and the Ar- gus II represents an early milestone in this effort. A number of other devices are in various stages of development. Although there are likely to remain a limited number of centers and sur- geons who perform this specialized procedure throughout the world, read- ers are sure to find Dr. Hahn's insights on the Argus II Retinal Prosthesis en- lightening. Science fiction has long predicted the development of artificial vision to restore sight to the blind. In 2013, the Argus II retinal prosthesis (Second Sight Medical Products, Sylmar, CA) was approved by the U.S. Food and Drug Administration (FDA), having received the Conformité Européenne (CE) mark 2 years prior in 2011 and approval by Health Canada in 2015. This device provides artificial visual stimulation otherwise permanently lost and consists of an external (wearable) and internal (surgically implanted) component. The external equipment includes custom glasses that house a video micro- camera connected by a wired cable to a video processing unit (VPU) (Figure 1A). The VPU transforms video from the micro-camera to data that are then transmitted wirelessly to the surgically placed internal implant, which receives power wirelessly via induction from the external hardware. The implanted component consists of a receiving coil and electronics case secured to the eye in a scleral buckle fashion and a 60-electrode array that is fixed to the inner surface of the retina with a retinal tack (Figure 1B). Wireless communication from the external VPU stimulates electrodes within the array to emit small electrical pulses that excite remaining viable inner retina cells, including ganglion cells. These artificially stimu- lated retinal ganglion cells transmit signals through the visual pathway to elicit patterns of light. 1 INDICATIONS Although retina specialists may not routinely encounter the Argus II, most eye care providers will likely be asked about this technology by patients, including those who may be eligible for this device. The Argus II is currently FDA-approved in the U.S. for a well-defined subset of patients: adults (age 25 years or old- er) with a diagnosis of retinitis pigmentosa (RP) and a history of prior useful vision who have progressed to bare light perception or no light perception vision in both eyes. Contraindications in- clude comorbidities that would prevent the implant from func- tioning properly (eg, optic nerve disease, cortical blindness, his- tory of retinal detachment, retinal vascular occlusion, trauma, and severe strabismus). Other contraindications include condi- tions that would prevent adequate implantation of the Argus II Paul Hahn doi: 10.3928/23258160-20181002-01 Howard F. Fine Practical Retina Co-Editor

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