Identify Optimal Non-invasive Brain Stimulation Paradigm for Improving Peripheral Vision
Glaucoma is a complex disease that can result in progressive vision loss. There are no treatments that restore vision lost to glaucoma. However, recent studies have shown that vision can be improved by non-invasive brain (NIBS) stimulation and visual training. In this study, we aim to compare and find out the optimal non-invasive brain stimulation model (transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial random noise stimulation (tRNS)) for improving peripheral vision in glaucoma patients. The proposed treatment is the application of transcranial electrical stimulation (tES) onto the participant's head, with brain stimulation aimed at the Primary Visual Cortex toward the occipital pole. The investigators hypothesize that the tES will enable higher performance in the reading task and secondary measures due to an increase in the cortical excitability of the stimulated brain cells, and tRNS will generate the greatest acute improvement in peripheral vision than either a-tDCS, tACS, or sham stimulation.
• Age range from 18 to 80 years;
• Diagnosis of primary open angle or normal tension glaucoma with relative scotoma in both eyes;
• A relative scotoma defined as a Humphrey Field Analyser (HFA) threshold perimetry loss (mean deviation of ≤-6dB) within the central 30° of the visual field for at least one eye;
• Best-corrected distance visual acuity of 6/12 or better (equivalent to 0.3 logMAR acuity or better to confirm that participant's central vision is preserved);
• Stable vision and visual field loss for at least 3 months;
• With a cognitive functional score of 22 or above in the Montreal Cognitive Assessment - Hong Kong version (HK-MoCA) (to confirm participant's intact cognitive function).