GlaucomaNCT04846140
Optimal Non-invasive Brain Stimulation for Peripheral Vision
A study testing transcranial electrical stimulation (tES) in people with Glaucoma, run by The Hong Kong Polytechnic University at 1 site in China.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Glaucoma
- What is being tested?
- transcranial electrical stimulation (tES)
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteChina
- Study dates
- 1 Nov 2021to Sep 2025
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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).
Who cannot join
- 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);
- 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);
- Self-reported vestibular or cerebellar dysfunction, history of vertigo;
- Using any medications for any neurological conditions or psychiatric drugs (e.g. sedative, hypnotic) that might interfere with motor control;
- Contraindications for non-invasive brain stimulation.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
China1 site, 1 recruiting
- Recruiting
Allen MY Cheong
Hong Kong
Allen MY Cheong, PhD, allen.my.cheong@polyu.edu.hk
About this study
Official title: 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.
Read the 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
- Being tested
- transcranial electrical stimulation (tES)
- Keywords
- glaucoma, non-invasive brain stimulation, peripheral vision
- Medical subject headings
- Glaucoma
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
transcranial electrical stimulation (tES)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.
| Study group | Role | What they receive |
|---|---|---|
| tDCS group | Experimental | 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. Receives: Device: transcranial electrical stimulation (tES) |
| tACS group | Experimental | 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. Receives: Device: transcranial electrical stimulation (tES) |
| tRNS group | Experimental | 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. Receives: Device: transcranial electrical stimulation (tES) |
| sham group | Experimental | 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. Receives: Device: transcranial electrical stimulation (tES) |
What is being measured
The primary outcome is the main question the study is designed to answer.
High-resolution perimetry (HRP)
Visual field will be measured using high-resolution perimetry (HRP, HighTechVision, Sweden), which is a valid and reliable computer-based campimetric visual field assessment. Suprathreshold stimuli will be presented in random order at 474 different positions to one eye (i.e. the eye with larger field loss) while fixation is monitored. Detection accuracy and response times will be recorded to map the patient's area of residual vision (i.e. relative scotoma). Testing will occur pre- and immediately post- stimulation.
Measured: 0.5-1 hour
Secondary outcomes (1)
Multifocal visual evoked potential (mfVEP)
Electrophysiological changes at visual cortex will be measured by multifocal visual evoked potential (mfVEP), a non-invasive neuroimaging technique related to electroencephalography (EEG) that is well established in the literature as a method for evaluating deficits in the visual field. Suprathreshold sectors of a circular checkerboard pattern will undergo visual reversal in a pseudorandom order to establish a visual evoked potential for each sector. Evoked potentials will be measured using a reference electrode placed at Fpz (i.e. forehead) and an array of 4 measurement electrodes arranged surrounding Oz (i.e. at the back of head). Subjects will be instructed to maintain fixation at the center of the screen while passively viewing the array of the stimulus, which will last approximately 12 minutes per session. Testing will occur pre- and immediately post- stimulation.
Measured: 0.5-1 hour
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Apr 2021
- Study start1 Nov 2021
- Primary completionJul 2025 (estimated)
- Study completionSep 2025 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for GlaucomaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- 3 sessions of 3 types of active brain stimulation and 1 session of placebo sham stimulation. Each participant will perform four sessions in a randomly-assigned order.
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- The Hong Kong Polytechnic University
- Sponsor type
- University, hospital or other
- Collaborators
- Chinese University of Hong Kong, The University of Hong Kong, University of Waterloo, Hong Kong Metropolitan University, Otto-von-Guericke University Magdeburg
- Responsible party
- Principal investigator, Allen MY Cheong, The Hong Kong Polytechnic University
- Investigators
- Allen Cheong, PhD, Principal investigator, The Hong Kong Polytechnic University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04846140
- Sponsor's protocol ID
- R5047-19
- Status last verified
- Oct 2024
- First submitted
- 12 Apr 2021
- Last updated
- 29 Oct 2024
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: IPD that underlie results in a publication will be available upon reasonable request to the research team.
Study at a glance
From the registry record, last updated by the sponsor on 29 Oct 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Identify Optimal Non-invasive Brain Stimulation Paradigm for Improving Peripheral Vision
- ClinicalTrials.gov ID
- NCT04846140
- Acronym / sponsor ID
- R5047-19
- Conditions
- Glaucoma
- Keywords
- glaucoma, non-invasive brain stimulation, peripheral vision
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- The Hong Kong Polytechnic UniversityUniversity, hospital or other
- Collaborators
- Chinese University of Hong Kong, The University of Hong Kong, University of Waterloo, Hong Kong Metropolitan University, Otto-von-Guericke University Magdeburg
- Study start
- 1 Nov 2021 (actual)
- Primary completion
- Jul 2025 (estimated)
- Study completion
- Sep 2025 (estimated)
- First posted
- 15 Apr 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 4
- Model description
- 3 sessions of 3 types of active brain stimulation and 1 session of placebo sham stimulation. Each participant will perform four sessions in a randomly-assigned order.
| Arm | Type | Receives |
|---|---|---|
| tDCS group | Experimental | Device: transcranial electrical stimulation (tES)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. |
| tACS group | Experimental | Device: transcranial electrical stimulation (tES)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. |
| tRNS group | Experimental | Device: transcranial electrical stimulation (tES)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. |
| sham group | Experimental | Device: transcranial electrical stimulation (tES)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. |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- 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;
Key exclusion criteria (5 listed)
- 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);
- 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);
- Self-reported vestibular or cerebellar dysfunction, history of vertigo;
- Using any medications for any neurological conditions or psychiatric drugs (e.g. sedative, hypnotic) that might interfere with motor control;
- Contraindications for non-invasive brain stimulation.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| 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. | Device | sham group, tACS group, tDCS group, tRNS group |
Primary outcome
High-resolution perimetry (HRP)
Time frame: 0.5-1 hour
Visual field will be measured using high-resolution perimetry (HRP, HighTechVision, Sweden), which is a valid and reliable computer-based campimetric visual field assessment. Suprathreshold stimuli will be presented in random order at 474 different positions to one eye (i.e. the eye with larger field loss) while fixation is monitored. Detection accuracy and response times will be recorded to map the patient's area of residual vision (i.e. relative scotoma). Testing will occur pre- and immediately post- stimulation.
1 secondary outcome
Multifocal visual evoked potential (mfVEP)
Time frame: 0.5-1 hour
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Oct 2024.
- Individual participant dataSharing planned: Yes. IPD that underlie results in a publication will be available upon reasonable request to the research team.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Allen Cheong, PhD principal investigator
The Hong Kong Polytechnic University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing transcranial electrical stimulation (tES) in people with Glaucoma, run by The Hong Kong Polytechnic University at 1 site in China.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 29 Oct 2024. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in China. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Allen Cheong, PhD (852-27666108, allen.my.cheong@polyu.edu.hk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
High-resolution perimetry (HRP) (time frame: 0.5-1 hour). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Oct 2024; AzTrials last refreshed its copy on 29 Oct 2026.