Effectiveness and Safety of Non-Invasive Neuromodulation for Vision Restoration: A Systematic Review and Meta-Analysis

ABSTRACT

We carried out a systematic review and meta-analysis to determine the effectiveness and safety of non-invasive electrical stimulation (NES) for vision restoration. We systematically searched for randomised controlled trials (RCTs) comparing NES with sham stimulation, for vision restoration between 2000 and 2022 in CENTRAL, MEDLINE, EMBASE, and LILACS. The main outcomes were as follows: visual acuity (VA); detection accuracy; foveal threshold; mean sensitivity as the parameter for the visual field; reading performance; contrast sensitivity (CS); electroencephalogram; quality of life (QoL), and safety. Two reviewers independently selected studies, extracted data, and evaluated the risk of bias using the Cochrane risk of bias 2.0 tool. The certainty in the evidence was determined using the GRADE framework. Protocol registration: CRD42022329342. Thirteen RCTs involving 441 patients with vision impairment indicate that NES may improve VA in the immediate post-intervention period (mean difference [MD] = −0.02 logMAR, 95% confidence intervals [CI] −0.08 to 0.04; low certainty), and probably increases QoL and detection accuracy (MD = 0.08, 95% CI −0.25 to 0.42 and standardised MD [SMD] = 0.09, 95% CI −0.58 to 0.77, respectively; both moderate certainty). NES likely results in little or no difference in mean sensitivity (SMD = −0.03, 95% CI −0.53 to 0.48). Compared with sham stimulation, NES increases the risk of minor adverse effects (risk ratio = 1.24, 95% CI 0.99 to 1.54; moderate certainty). The effect of NES on CS, reading performance, and electroencephalogram was uncertain. Our study suggests that although NES may slightly improve VA, detection accuracy, and QoL, the clinical relevance of these findings remains uncertain. Future research should focus on improving the available evidence’s precision and consistency.

KEYWORDS:

• Vision disorders
• electrostimulation
• electric stimulation therapy
• systematic review
• quality of life

Acknowledgments

The authors thank the Universidad de los Andes for their excellent support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethical approval statement

The study was designed in accordance with the Declaration of Helsinki and received approval from the Andes Ethics Committee (Evaluation Report Number: 20220407).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01658107.2023.2279092.

Additional information

Funding

The authors reported that there is no funding associated with the work featured in this article.