Non-invasive Brain Stimulation for Treating Visual Defects: A Systematic Review and Meta-analysis
Ahmed Abbas1, Heba Aboeldahab2, Amr Hassan3, Mostafa Meshref4, Amr Elrosasy5, Safia Lorabi6, Yousef Hawas7, Benyameen Mosa8, Ahmed Negida9
1Faculty of Medicine, Mansoura University, Egypt, 2Clinical researcher at Al-Gomhoria General Hospital, Biomedical Informatics and medical statistics master degree candidate, 3Ophthalmology Department, Faculty of Medicine, South Valley University, Qena, Egypt, 4Al-Azhar University, Cairo, 5Faculty Of Medicine, Cairo University, Cairo, Egypt, 6Azur plage Physical Medicine And Rehabilitation center, 7Faculty of Medicine, Tanta University, Egypt, 8Misr University for Science and Technology, 9Virginia Commonwealth University
Objective:
We evaluated the efficacy of applying repetitive transorbital alternating current stimulation (rTACS) to patients suffering from visual defects, especially homonymous hemianopia.
Background:
Visual functions are entangled with cortical areas responsible for transcoding the images we see each second. Moreover, cortical integrity is important for visual functions to operate properly. Stroke, optic neuropathy, or glaucoma would result in vision loss or Visual field defect (VFD). In addition, homonymous hemianopia is a commonly observed defect. Recently, one of the commonly used procedures to relieve VFD is non-invasive brain stimulation (NIBS): a superficial stimulator coil that generates an electric current directed to the area of interest.
Design/Methods:
A comprehensive search covering publications in PubMed, Embase, Cochrane, and Scopus, spanning until September 2023 was performed. Relevant Randomized controlled trials (RCTs) were selected, and their data were extracted and analyzed using the R (V.4.2.2) software. Pooled mean difference (MD) was calculated for change in the high-resolution perimetry detection accuracy (HRP DA) and fixation accuracy (HRP FA), static automated perimetry foveal threshold (SAP FT), and visual acuity (VA) of near vision outcomes.
Results:
We included 4 RCTs with a total of 228 patients. Compared to the sham group, rTACS patients had a significantly higher HRP DA (MD= 0.35; 95% CI [0.003,0.694] P=0.048). However, the pooled analysis did not favor any of the compared groups in HRP FA, SAP FT, VA of near vision, and mean threshold (MD=0.14; 95%CI [-0.21,0.48] P=0.43], (MD= 0.17; 95%CI [-0.11,0.45] P=0.23), (MD= 0.32; 95%CI [-0.24,0.88] P=0.26), and (MD= 0.31; 95%CI [-0.04,0.65] P=0.08) respectively.
Conclusions:
Current evidence suggests that rTACS exhibits a promising approach in homonymous hemianopia patients, where it significantly increased HRP DA. Despite the results' failure to attain statistical significance in some outcomes, it underscores the necessity for larger RCTs with longer follow-up periods.