Optimal Non-invasive Brain Stimulation for Peripheral Vision

NCT ID: NCT04846140

Last Updated: 2024-10-29

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 40 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2021-11-01
• Study Completion Date: 2025-09-30

Brief Summary

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.

Detailed Description

This study uses a within-subjects, double-blind, placebo-controlled design and will be carried out in Hong Kong (The Hong Kong Polytechnic University).

Participants who will be recruited are 40 glaucoma patients aged 18 to 80, diagnosed with primary open-angle or normal-tension glaucoma with relative scotoma in both eyes. All participants will take part in 4 stimulation sessions (completion of active a-tDCS, tACS, tRNS, and sham stimulation in random order) with at least 48-hour separation between visits to wash out active stimulation effects.

The primary outcome is high-resolution perimetry that will be used to measure the visual field of participants. The secondary outcome is multifocal visual evoked potential (mfVEP) that will be used to measure the electrophysiological changes in the visual cortex.

The study consists of 5 visits:

Visit 1: Eligibility assessment (refer to the inclusion and exclusion criteria).

Visits 2 - 5: Stimulation sessions (completion of active a-tDCS, tACS, tRNS, and sham stimulation in random order) with at least 48-hours separation between visits to wash out active stimulation effects. An established protocol will be used. Briefly, active a-tDCS (2 mA), tACS (2 mA), tRNS (2 mA) or sham a-tDCS will be delivered for 20 minutes. The anodal electrode will be placed at Oz (visual cortex) while the cathodal electrode will be placed on the left cheek to facilitate stimulation of cells corresponding to the para-central retina that are located within the calcarine sulcus. Active stimulation will involve the delivery of 2 mA current continuously, while the fade-in-short-stimulation-fade-out approach will be used for the sham condition, in which the stimulation will be ramped down after 30 seconds of stimulation. Both the participant and experimenter will be masked to the stimulation type.

The average detection accuracy, response time, and functional connectivity will be analyzed using a within-subjects ANOVA with factors of Stimulation type (a-tDCS vs. tACS vs. tRNS vs. sham) and Time (pre and post-stimulation). Significant interactions will be investigated using post-hoc Bonferroni-adjusted paired sample t-tests. A significant interaction between Stimulation type and Time for the primary outcome followed by a significant post-hoc comparison with a p-value <0.05 favoring tRNS would be consistent with our hypothesis.

Conditions

Glaucoma

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: TREATMENT
• Blinding Strategy: DOUBLE

Study Groups

tDCS group

This group is defined as the participants who will receive tDCS at the first session. Participants in this group will receive 4 stimulation types (active a-tDCS, tACS, tRNS, and sham) in random order with at least a 48-hour separation between visits.

Group Type: EXPERIMENTAL

transcranial electrical stimulation (tES)

Intervention Type: DEVICE

Transcranial electrical stimulation (tES) is a form of neuromodulation that uses constant, low direct current delivered via the electrodes on the skull. Three types of tES will be applied in this study, include a-tDCS, tACS, and tRNS. Additionally, sham stimulation will be applied as a placebo-controlled intervention.

tACS group

This group is defined as the participants who will receive tACS at the first session. Participants in this group will receive 4 stimulation types (active a-tDCS, tACS, tRNS, and sham) in random order with at least a 48-hour separation between visits.

Group Type: EXPERIMENTAL

transcranial electrical stimulation (tES)

Intervention Type: DEVICE

Transcranial electrical stimulation (tES) is a form of neuromodulation that uses constant, low direct current delivered via the electrodes on the skull. Three types of tES will be applied in this study, include a-tDCS, tACS, and tRNS. Additionally, sham stimulation will be applied as a placebo-controlled intervention.

tRNS group

This group is defined as the participants who will receive tRNS at the first session. Participants in this group will receive 4 stimulation types (active a-tDCS, tACS, tRNS, and sham) in random order with at least a 48-hour separation between visits.

Group Type: EXPERIMENTAL

transcranial electrical stimulation (tES)

Intervention Type: DEVICE

Transcranial electrical stimulation (tES) is a form of neuromodulation that uses constant, low direct current delivered via the electrodes on the skull. Three types of tES will be applied in this study, include a-tDCS, tACS, and tRNS. Additionally, sham stimulation will be applied as a placebo-controlled intervention.

sham group

This group is defined as the participants who will receive sham stimulation at the first session. Participants in this group will receive 4 stimulation types (active a-tDCS, tACS, tRNS, and sham) in random order with at least a 48-hour separation between visits.

Group Type: EXPERIMENTAL

transcranial electrical stimulation (tES)

Intervention Type: DEVICE

Transcranial electrical stimulation (tES) is a form of neuromodulation that uses constant, low direct current delivered via the electrodes on the skull. Three types of tES will be applied in this study, include a-tDCS, tACS, and tRNS. Additionally, sham stimulation will be applied as a placebo-controlled intervention.

Interventions

transcranial electrical stimulation (tES)

Transcranial electrical stimulation (tES) is a form of neuromodulation that uses constant, low direct current delivered via the electrodes on the skull. Three types of tES will be applied in this study, include a-tDCS, tACS, and tRNS. Additionally, sham stimulation will be applied as a placebo-controlled intervention.

Intervention Type: DEVICE

Eligibility Criteria

Inclusion Criteria

1. Age range from 18 to 80 years;

2. Diagnosis of primary open angle or normal tension glaucoma with relative scotoma in both eyes;

3. 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;

4. 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);

5. Stable vision and visual field loss for at least 3 months;

6. 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).

Exclusion Criteria

1. Ocular diseases other than glaucoma (e.g. age-related macular degeneration, diabetic retinopathy, moderate to severe cataract) or severe hearing impairment (to ensure that participant can hear the instructions clearly during assessments and training);

2. Severe medical problems (e.g. stroke, Parkinson's disease) or self-reported neurological (e.g. brain surgery, brain tumor, peripheral neuropathy), or cognitive disorders (e.g. diagnosed dementia or cognitive impairment);

3. Self-reported vestibular or cerebellar dysfunction, history of vertigo;

4. Using any medications for any neurological conditions or psychiatric drugs (e.g. sedative, hypnotic) that might interfere with motor control;

5. Contraindications for non-invasive brain stimulation.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 80 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Chinese University of Hong Kong

OTHER

Sponsor Role: collaborator

The University of Hong Kong

OTHER

Sponsor Role: collaborator

University of Waterloo

OTHER

Sponsor Role: collaborator

Hong Kong Metropolitan University

OTHER

Sponsor Role: collaborator

Otto-von-Guericke University Magdeburg

OTHER

Sponsor Role: collaborator

The Hong Kong Polytechnic University

OTHER

Sponsor Role: lead

Responsible Party

Allen MY Cheong

Associate professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Allen Cheong, PhD

Role: PRINCIPAL_INVESTIGATOR

The Hong Kong Polytechnic University

Locations

Allen MY Cheong

Hong Kong, , China

Site Status: RECRUITING

Countries

China

Central Contacts

Allen Cheong, PhD

Role: CONTACT

allen.my.cheong@polyu.edu.hk

852-27666108

Ben Thompson, PhD

Role: CONTACT

ben.thompson@uwaterloo.ca

852-27666108

Facility Contacts

Allen MY Cheong, PhD

Role: primary

allen.my.cheong@polyu.edu.hk

Provided Documents

Document Type: Statistical Analysis Plan

View Document

Other Identifiers

R5047-19

Identifier Type: -

Identifier Source: org_study_id