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NCT Number: NCT07486323

Combined Non-Invasive Brain and Visual Stimulation for Vision Improvement

Glaucoma is a complex disease that can result in progressive vision loss. It is the second leading cause of blindness, accounting for 23% of permanent blindness in Hong Kong. There are no treatments that restore vision lost to glaucoma. This study will examine the effect of transcranial direct current stimulation (NIBS) on improving quality of life, visual function and functional performance in patients with peripheral field loss due to glaucoma.

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Key information

Conditions

Glaucoma Open-Angle Eye Diseases Glaucoma Glaucoma, Open-Angle Ocular Hypertension

Age range

40 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

About this study

This study uses a prospective, single-masked, randomized, cross-over, placebo-controlled training RCT design.

The eligible participants will be randomly allocated into 4 groups:

(A) Transcranial direct current stimulation; (B) Visual Tetanic Stimulation; (C) Transcranial direct current stimulation+ Visual Tetanic Stimulation; (D) Sham. All participants will underwent all the 4 types of intervention with a 14 days washing out period between intervention types:

All participants will complete twenty-six study visits:

Visit 1: Eligibility assessment (refer to the recruitment criteria); Visit 2: Outcome measures (Pre-intervention/ baseline); Visit 3-7: 5 sessions intervention (1st intervention block); Visit 8: Post 1 outcome measures; Visit 9-13: 5 sessions intervention (2nd intervention block); Visit 14: Post 2 outcome measures; Visit 15-19: 5 sessions intervention (3rd intervention block); Visit 20: Post 3 outcome measures; Visit 21-25: 5 sessions intervention (4th intervention block); Visit 26: Post 4 outcome measures

Eight sessions of assessment will be conducted: (1) Baseline-1; (2) Post-1 (after 5-sessions training); (3) Baseline-2; (4) Post-2 (after 5-sessions training); (5) Baseline-3; (6) Post-3 (after 5-sessions training); (7) Baseline-4; and (8) Post-4 (after 5-sessions training).

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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 24 degree 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).

Exclusion criteria

  • 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 motor control;
  • Contraindications for non-invasive brain stimulation.

Treatment and study plan

NIBS

Other

Around 1 hour

VTS

Other

Around 1 hour

NIBS+VTS

Other

Around 1 hour

SHAM

Other

Around 1 hour

Primary outcomes

  1. Visual field test

    Time frame: Baseline (before the first intervention session), and immediately before and after each intervention block (5 session of intervention)

    Visual field test is measured monocularly using the 24-2 Swedish interactive threshold algorithm (SITA) standard tests by Humphrey visual field analyzer (HFA, Carl Zeiss Meditec Inc., California). The mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI) are recorded, and the MD of the 24-2 visual field test will be used as the primary outcome of intervention effect.

  2. Electroencephalography (EEG)

    Time frame: Baseline (before the first intervention session), and immediately before and after each intervention block (5 session of intervention)

    Electrophysiological function is assessed using a 64-channel high-resolution electroencephalography (EEG) system. EEG outcome measures include spectral power in the delta, theta, alpha, beta, and gamma frequency bands, with particular focus on alpha-band activity, as well as functional connectivity measures derived from scalp EEG recordings, including coherence, phase-based connectivity, and related network indices.

    Pattern-reversal visual evoked potentials (PR-VEP) are recorded during presentation of a high-contrast checkerboard stimulus to the central 20-degree visual field under monocular viewing conditions. Stimuli are presented at 0.5 Hz and 1.5 Hz with 40 reversals. PR-VEP outcome measures include N75 latency, P100 latency, N135 latency, and N75-P100 and/or P100-N135 amplitude.

  3. Optical Coherence Tomography (OCT)

    Time frame: Baseline (before the first intervention session), and immediately before and after each intervention block (5 session of intervention)

    Retinal nerve fiber layer is measured using spectral-domain Optical Coherence Tomography (OCT). Peripapillary retinal nerve fiber layer thickness is obtained from a circular scan centered on the optic nerve head. Ganglion cell thickness is measure using macular OCT imaging

  4. Optical Coherence Tomography Angiography (OCT-A)

    Time frame: Baseline (before the first intervention session), and immediately before and after each intervention block (5 session of intervention)

    Evaluation of retinal vascular function in glaucoma patients is measured. Detailed visualisation of microvasculature structure within the retina and optic nerve head is measured, change of ocular perfusion is shown.

Study contacts

Contact information is provided by the study sponsor or research team.

Lok Hin Chan, BSc (Hons) in Optometry

CONTACT

[email protected]

852-34002309

Ming Yan Cheong, PhD

CONTACT

[email protected]

852-27666108

Sponsors and collaborators

Lead sponsor

The Hong Kong Polytechnic University

Other

Registry information

Official study title

Evaluation of Combined Non-invasive Brain Stimulation (NIBS) and Visual Tetanic Stimulation (VTS) for Vision Enhancement: A Randomized, Single-blind, Cross-over Trial

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Mar 20, 2026
Registry last updated
Mar 24, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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