Retinal implantation of electronic vision prostheses to treat retinitis pigmentosa: A systematic review

Abstract Purpose Retinitis pigmentosa is an hereditary disease causing photoreceptor degeneration and permanent vision loss. Retinal implantation of a stimulating electrode array is a new treatment for retinitis pigmentosa, but quantification of its efficacy is the subject of ongoing work. This review evaluates vision-related outcomes resulting from retinal implantation in participants with retinitis pigmentosa. Methods We searched MEDLINE and Embase for journal articles published since 1 January 2015. We selected articles describing studies of implanted participants that reported post-implantation measurement of vision. We extracted study information including design, participants’ residual vision, comparators, and assessed outcomes. To assess risk of bias, we used signalling questions and a target trial. Results Our search returned 425 abstracts. We reviewed the full text of 34 articles. We judged all studies to be at high risk of bias due to study design or experimental conduct. Regarding design, studies lacked the measures that typical clinical trials take to protect against bias (e.g., control groups and masking). Regarding experimental conduct, outcome measures were rarely comparable before and after implantation, and psychophysical methods were prone to bias (subjective, not forced-choice, methods). The most common comparison found was between post-implantation visual function with the device powered off versus on. This comparison is at high risk of bias. Conclusions There is a need for high-quality evidence of efficacy of retinal implantation to treat retinitis pigmentosa. Translational Relevance For patients and clinicians to make informed choices about retinitis pigmentosa treatment, visual function restored by retinal implantation must be properly quantified and reported.