Abstract
BackgroundRetinitis pigmentosa is an incurable, degenerative retinal condition causing progressive sight loss, significantly affecting patients’ quality of life. The Argus II Retinal Prosthesis is a surgically implanted medical device that delivers electrical stimulation to the retina. It is intended to produce a form of artificial vision for blind people with severe-to-profound retinitis pigmentosa by stimulating the remaining viable retinal cells to induce visual perception. This study has been initiated by National Health Service England’s Commissioning through Evaluation program and funded through the National Institute of Health Research of the United Kingdom.ObjectiveThe aim of this study was to assess the effect of the Argus II device on patient’s daily activities and quality of life.MethodsThis protocol is a prospective, single-arm, open-label, mixed methods study on 10 consecutive participants receiving the Argus II device. The patient representatives played an integral role in the design of this study. Eligibility criteria include ultra-low vision in both eyes as a result of end-stage retinitis pigmentosa and a willingness and capacity to complete the postimplantation rehabilitation program. Participants will be interviewed by independent researchers at baseline and 12 months later by using a semistructured, in-depth approach, alongside validated questionnaires (Impact of Vision Impairment-Very Low Vision, 5-level EuroQoL-5 dimensions scale, EuroQoL-visual analog scale, and Hospital Anxiety and Depression Scale) and a bespoke device-related questionnaire, which includes questions about users’ experiences with the procedure, the device, and rehabilitation. The effect of the device on patients’ functional vision and activities of daily living will be assessed by vision rehabilitation specialists using a set of tests measured on an ordinal scale (eg, ability to locate objects and avoid obstacles). Clinical outcomes include full-field stimulus light threshold, square localization, direction of motion, grating visual acuity, Landolt-C, procedural success, and adverse events. Qualitative and quantitative outcomes will be linked in a single database to enable individual participant measures to be considered in toto, comparing baseline to the final review.ResultsThis study was approved by the local ethics committee on April 24, 2019 (London-Camberwell St. Giles Research Ethics Committee, reference 19/LO/0429). It has also been approved by the Health Research Authority and Health and Care Research Wales. At the time of protocol writing, Argus II was available for use in the United Kingdom; however, the manufacturer recently withdrew the Argus II device from sale in the United Kingdom. Therefore, the study is not going ahead at this time.ConclusionsThe mixed methods approach provides a rich and in-depth assessment of the effect of the device on participants’ quality of life. Despite the work not going ahead, the publication of this publicly funded protocol is important for researchers planning similar work.International Registered Report Identifier (IRRID)PRR1-10.2196/17436
Highlights
BackgroundRetinitis pigmentosa is a term for a group of genetically determined degenerative eye conditions that cause progressive loss of retinal photoreceptors
Participants will be interviewed by independent researchers at baseline and 12 months later by using a semistructured, in-depth approach, alongside validated questionnaires (Impact of Vision Impairment-Very Low Vision, 5-level EuroQoL-5 dimensions scale, EuroQoL-visual analog scale, and Hospital Anxiety and Depression Scale) and a bespoke device-related questionnaire, which includes questions about users’ experiences with the procedure, the device, and rehabilitation
The Argus II Retinal Prosthesis is a medical device that is surgically implanted into only 1 eye and it delivers electrical stimulation to the retina
Summary
Retinitis pigmentosa is a term for a group of genetically determined degenerative eye conditions that cause progressive loss of retinal photoreceptors It typically starts with mild loss of peripheral vision, but as the disease advances, vision reduces to a small island of central vision, which may be lost at the end stages of the disease. It is intended to produce a form of artificial vision to blind people with severe-to-profound retinitis pigmentosa by stimulating the remaining viable retinal cells to induce visual perception It aims to provide functional vision, which enables patients to perceive light, movement, and shapes. The core element of the Argus II system is a spectacle-mounted video camera that records real-time images and a video processing unit that converts the images into data that are wirelessly transmitted to an episcleral receiver unit (Figure 1) This relays data to the electrode array, which produces electrical impulses that bypass damaged photoreceptors and stimulate the retina’s remaining cells.
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