Dataset Information

Effects of the Argus II Retinal Prosthesis System on the Quality of Life of Patients With Ultra-Low Vision Due to Retinitis Pigmentosa: Protocol for a Single-Arm, Mixed Methods Study.

ABSTRACT:

Background

Retinitis 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.

Objective

The aim of this study was to assess the effect of the Argus II device on patient's daily activities and quality of life.

Methods

This 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.

Results

This 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.

Conclusions

The 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.

SUBMITTER: White J

PROVIDER: S-EPMC7857949 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Publications

Effects of the Argus II Retinal Prosthesis System on the Quality of Life of Patients With Ultra-Low Vision Due to Retinitis Pigmentosa: Protocol for a Single-Arm, Mixed Methods Study.

White Judith J Knight Laura L da Cruz Lyndon L Stanga Paulo E PE Patrick Hannah H Powell Helen H Berry Lee L Withers Kathleen K Carolan-Rees Grace G Jackson Timothy L TL

JMIR research protocols 20210120 1

<h4>Background</h4>Retinitis 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 stud ...[more]

PMID: 33470946

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Project description:Retinitis pigmentosa is a group of genetic disorders that involves the breakdown and loss of photoreceptors in the retina, resulting in progressive retinal degeneration and eventual blindness. The Argus II Retinal Prosthesis System is the only currently available surgical implantable device approved by Health Canada. It has been shown to improve visual function in patients with severe visual loss from advanced retinitis pigmentosa. The objective of this analysis was to examine the clinical effectiveness, cost-effectiveness, budget impact, and safety of the Argus II system in improving visual function, as well as exploring patient experiences with the system.We performed a systematic search of the literature for studies examining the effects of the Argus II retinal prosthesis system in patients with advanced retinitis pigmentosa, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on visual function, functional outcomes, quality of life, and adverse events. We developed a Markov decision-analytic model to assess the cost-effectiveness of the Argus II system compared with standard care over a 10-year time horizon. We also conducted a 5-year budget impact analysis. We used a qualitative design and an interview methodology to examine patients' lived experience, and we used a modified grounded theory methodology to analyze information from interviews. Transcripts were coded, and themes were compared against one another.One multicentre international study and one single-centre study were included in the clinical review. In both studies, patients showed improved visual function with the Argus II system. However, the sight-threatening surgical complication rate was substantial. In the base-case analysis, the Argus II system was cost-effective compared with standard care only if willingness-to-pay was more than $207,616 per quality-adjusted life-year. The 5-year budget impact of funding the Argus II system ranged from $800,404 to $837,596. Retinitis pigmentosa significantly affects people's ability to navigate physical and virtual environments. Argus II was described as enabling the fundamental elements of sight. As such, it had a positive impact on quality of life for people with retinitis pigmentosa.Based on evidence of moderate quality, patients with advanced retinitis pigmentosa who were implanted with the Argus II retinal prosthesis system showed significant improvement in visual function, real-life functional outcomes, and quality of life, but there were complications associated with the surgery that could be managed through standard ophthalmologic treatments. The costs for the technology are high.

Project description:PURPOSE:The Argus II epiretinal prosthesis has been developed to provide partial restoration of vision to subjects blinded from outer retinal degenerative disease. Participants were surgically implanted with the system in the United States and Europe in a single arm, prospective, multicenter clinical trial. The purpose of this investigation was to determine which factors affect electrical thresholds in order to inform surgical placement of the device. METHODS:Electrode-retina and electrode-fovea distances were determined using SD-OCT and fundus photography, respectively. Perceptual threshold to electrical stimulation of electrodes was measured using custom developed software, in which current amplitude was varied until the threshold was found. Full field stimulus light threshold was measured using the Espion D-FST test. Relationships between electrical threshold and these three explanatory variables (electrode-retina distance, electrode-fovea distance, and monocular light threshold) were quantified using regression. RESULTS:Regression analysis showed a significant correlation between electrical threshold and electrode-retina distance (R2 = 0.50, P = 0.0002; n = 703 electrodes). 90.3% of electrodes in contact with the macula (n = 207) elicited percepts at charge densities less than 1 mC/cm2/phase. These threshold data also correlated well with ganglion cell density profile (P = 0.03). A weaker, but still significant, inverse correlation was found between light threshold and electrical threshold (R2 < 0.52, P = 0.01). Multivariate modeling indicated that electrode-retina distance and light threshold are highly predictive of electrode threshold (R2 = 0.87; P < 0.0005). CONCLUSIONS:Taken together, these results suggest that while light threshold should be used to inform patient selection, macular contact of the array is paramount. TRANSLATIONAL RELEVANCE:Reported Argus II clinical study results are in good agreement with prior in vitro and in vivo studies, and support the development of higher-density systems that employ smaller diameter electrodes. (clinicaltrials.gov identifier: NCT00407602).

Dataset Information

Effects of the Argus II Retinal Prosthesis System on the Quality of Life of Patients With Ultra-Low Vision Due to Retinitis Pigmentosa: Protocol for a Single-Arm, Mixed Methods Study.

Background

Objective

Methods

Results

Conclusions

International registered report identifier (irrid)

Publications

Effects of the Argus II Retinal Prosthesis System on the Quality of Life of Patients With Ultra-Low Vision Due to Retinitis Pigmentosa: Protocol for a Single-Arm, Mixed Methods Study.

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