Brain Stimulation Effects on Orientation and Mobility Skills in Adults With Vision Impairment
NCT ID: NCT07341763
Last Updated: 2026-01-23
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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NOT_YET_RECRUITING
NA
20 participants
INTERVENTIONAL
2026-03-01
2027-08-31
Brief Summary
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Detailed Description
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Participants will be recruited from university-affiliated clinics as well as local clinical practices. After obtaining full informed consent at the first visit, participants will complete clinical tests to confirm that the eligibility criteria of the study are met. These tests include measuring the participant's corrected binocular distance and near visual acuities, binocular contrast sensitivity, binocularity, as well as peripheral visual fields. Researchers will also ensure that it safe for the participant to undergo brain stimulation using a list of contraindicators for brain stimulation interventions and verify that participants are free from physical or motor impairments as well as vestibular disorders or dysfunctions that can impact the participant's walking and balancing abilities.
During the two subsequent visits, the effects of stimulation (which lasts 20 minutes) will be studied 2 and 30 minutes after stimulation. To evaluate improvement, various measures of O\&M performance will be targeted as participants complete an O\&M course divided into 4 sections and composed of an array of static natural and artificial (man-made) obstacles. Participants will be instructed to walk along the various sections at a comfortable pace, safely negotiating the obstacles without touching any of the obstacles. Participants will also be told in which sections obstacles will be encounter. Static natural obstacles refer to fixed/steady/stable obstacles that are either readily found in the environment (e.g., potted plants) or form part of the architecture of the building (e.g., a pole or a sealed doorway). Artificial obstacles are made of light materials such as polystyrene, rubber foam, soft cardboard, or paper. Static natural/real obstacles will be at foot level, foot to knee height, as well as shoulder and head heights, whereas artificial obstacles will be placed either above the knee, waist, at the shoulder or head height. Individuals with constricted field loss in both eyes who use a long white cane for travelling and have received O\&M training (including caning skills) from an orientation and mobility professional will be asked to complete the course with their cane. However, individuals with constricted visual field in both eyes who do not use a cane can also complete the same course.
Measures of performance include the primary outcome measure percentage preferred walking speed (PPWS), that is the walking speed of the individual who is visually impaired in an environment with obstacles expressed as a percentage of their preferred walking speed in an unobstructed path. Secondary outcome measures include: the time taken to complete each of the 4 sections of the course, the number of O\&M errors, visual detection distance (VDD) (the distance at which an individual detects an obstacle in the travel path, even if it cannot be identified), and visual identification distance (VID) (the distance at which an individual can correctly identify an obstacle in the travel path).
Course section #1 will not consist of obstacles. The time taken to complete the course section, number of O\&M errors, and preferred walking speed in an unobstructed path (obtained from the completion time and length of the straight, flat path) will be measured.
Course section #2 will consist of obstacles and will be an indoor space leading to a more opened space within the building. The time taken to complete the course section, number of O\&M errors, and preferred walking speed in an obstructed path (obtained from the completion time and length of the path) will be measured. The percentage preferred walking speed (PPWS) will be calculated. PPWS is the preferred walking speed of the individual in course section #2 expressed as a percentage of the participant's preferred walking speed in course section #1.
Course sections #3 and #4 will be used for measuring VDD and VID. Each course will be a straight indoor corridor consisting of only one obstacle, and the obstacle will be different for each of the two sections. Moreover, course section #3 will be used as a training course for measuring VDD and VID. The time taken to complete the course section, number of O\&M errors, visual detection distance (VDD), and visual identification distance (VID) will be measured in course sections #3 and #4.
It is important to note that for course sections with obstacles (course sections # 2 to 4), the location of the obstacles in each trial (pre, post 1, and post 2) will not be varied, but rather the location of the obstacles on each treatment day will be randomized. In addition, two researchers will always be with the participant at all times. One will be with the participant to provide instructions and record data; whilst the other will be ahead of the participant to make sure the path is clear, record the times, and confirm that the obstacles are still in place (when applicable), as well as videorecord the session once consent was obtained from the participant at the first visit. By videorecording the participant as the course task is completed, the researchers will be able to obtain more accurate measures of time, and the number of O\&M errors.
There will be two stimulation sessions (one with active stimulation and one with placebo (the order will be randomized so that neither the participant nor the researcher will know what the subject will receive)). At the two stimulation sessions the primary and secondary outcome measures will be evaluated as the participant completes the O\&M course before stimulation (O\&M pretest), as well as 2 mins after stimulation (O\&M post-test 1/immediately after stimulation), and 30 mins after stimulation (O\&M post-test 2/30 minutes after stimulation).
The investigators hypothesize that the application of hf-tRNS to V1 will improve the orientation and mobility skills of individuals with constricted visual fields immediately following stimulation as a result of an increase in the cortical excitability of the stimulated brain cells, which consequently leads to peripheral vision and contrast sensitivity enhancements, thereby allowing the participants to safely detect objects and obstacles in the travel path. The objective of this study is to improve the fundamental visual processes of individuals with constricted visual fields using hf-tRNS. From a scientific perspective, the investigators hope to discover whether brain stimulation can serve as an additional rehabilitation tool for improving the O\&M skills of individuals with constricted visual fields. Investigators expect that participants will experience temporary O\&M improvements, however, there will not be any lasting improvements in O\&M skills from such a single session within subject study design. If the results of this study show a positive effect, the data will be used to power a larger study. All procedures will occur at the Human Visual Neuroscience Laboratory, University of Waterloo, Ontario, Canada.
Conditions
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Study Design
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RANDOMIZED
CROSSOVER
TREATMENT
DOUBLE
Study Groups
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Active brain stimulation (study visit 2) and Placebo/Sham (study visit 3)
Participants in this arm will be exposed to active stimulation for 20 minutes whilst seated quietly at treatment session 1 (study visit 2). They will then complete the orientation and mobility (O\&M) course 2-minutes and 30-minutes after stimulation. It is important to note that they will also complete the course before undergoing stimulation. In addition, individuals with constricted visual fields in both eyes who use a white cane for travelling will be encouraged to use their personal cane for the course, whereas those who do not use a cane will complete the course as they naturally would for any travel paths. Forty-eight hours later the same participants in this arm will be exposed to placebo/sham stimulation (study visit 3) and except for the treatment they receive that day, the same protocol from the previous visit will be executed, and the same outcome measures evaluated. Interventions: Active hf-tRNS at treatment (study visit 2); Placebo/sham hf-tRNS (study visit 3).
Active hf-tRNS.
Active hf-tRNS: A weak alternating electric current is applied to the head through two electrodes to affect the cortical excitability of the targeted cells in the brain.
Stimulation instrument: neuroConn DC Stimulator Plus 2019 (Direct current stimulator Model number 0021, power: 1.2 W, charger: 2.9 V (maximum 160 mA)) (neurocaregroup.com), or neuroConn DC Stimulator MC 2016 (Multi-channel stimulator Model number 0028, power: 24 W, rating: 12 V (maximum 2 A)) (neurocaregroup.com).
Placebo/sham hf-tRNS
Placebo/sham hf-tRNS: The tRNS machine will be used as in active stimulation, except the electrical current will not be applied.
Stimulation instrument: neuroConn DC Stimulator Plus 2019 (Direct current stimulator Model number 0021, power: 1.2 W, charger: 2.9 V (maximum 160 mA)) (neurocaregroup.com), or neuroConn DC Stimulator MC 2016 (Multi-channel stimulator Model number 0028, power: 24 W, rating: 12 V (maximum 2 A)) (neurocaregroup.com).
Placebo/sham (study visit 2) and Active brain stimulation (study visit 3)
Participants in this arm will be exposed to placebo/sham stimulation for 20 minutes whilst seated quietly at treatment session 1 (study visit 2). They will then proceed to complete the orientation and mobility (O\&M) course 2-minutes and 30-minutes after stimulation. It is important to note that they will also complete the course before undergoing stimulation. In addition, individuals with constricted visual fields in both eyes who use a white cane for travelling will be encouraged to use their personal cane for the course, whereas those who do not use a cane will complete the course as they naturally would for any travel paths. Forty-eight hours later the same participants in this arm will be exposed to active stimulation (study visit 3) and except for the treatment they receive that day, the same protocol from the previous visit will be executed, and the same outcome measures evaluated. Interventions: Placebo/sham hf-tRNS at treatment (study visit 2); Active hf-tRNS (study visit 3).
Active hf-tRNS.
Active hf-tRNS: A weak alternating electric current is applied to the head through two electrodes to affect the cortical excitability of the targeted cells in the brain.
Stimulation instrument: neuroConn DC Stimulator Plus 2019 (Direct current stimulator Model number 0021, power: 1.2 W, charger: 2.9 V (maximum 160 mA)) (neurocaregroup.com), or neuroConn DC Stimulator MC 2016 (Multi-channel stimulator Model number 0028, power: 24 W, rating: 12 V (maximum 2 A)) (neurocaregroup.com).
Placebo/sham hf-tRNS
Placebo/sham hf-tRNS: The tRNS machine will be used as in active stimulation, except the electrical current will not be applied.
Stimulation instrument: neuroConn DC Stimulator Plus 2019 (Direct current stimulator Model number 0021, power: 1.2 W, charger: 2.9 V (maximum 160 mA)) (neurocaregroup.com), or neuroConn DC Stimulator MC 2016 (Multi-channel stimulator Model number 0028, power: 24 W, rating: 12 V (maximum 2 A)) (neurocaregroup.com).
Interventions
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Active hf-tRNS.
Active hf-tRNS: A weak alternating electric current is applied to the head through two electrodes to affect the cortical excitability of the targeted cells in the brain.
Stimulation instrument: neuroConn DC Stimulator Plus 2019 (Direct current stimulator Model number 0021, power: 1.2 W, charger: 2.9 V (maximum 160 mA)) (neurocaregroup.com), or neuroConn DC Stimulator MC 2016 (Multi-channel stimulator Model number 0028, power: 24 W, rating: 12 V (maximum 2 A)) (neurocaregroup.com).
Placebo/sham hf-tRNS
Placebo/sham hf-tRNS: The tRNS machine will be used as in active stimulation, except the electrical current will not be applied.
Stimulation instrument: neuroConn DC Stimulator Plus 2019 (Direct current stimulator Model number 0021, power: 1.2 W, charger: 2.9 V (maximum 160 mA)) (neurocaregroup.com), or neuroConn DC Stimulator MC 2016 (Multi-channel stimulator Model number 0028, power: 24 W, rating: 12 V (maximum 2 A)) (neurocaregroup.com).
Eligibility Criteria
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Inclusion Criteria
* Have binocular visual acuity or best corrected binocular visual acuity no better than 6/12 or 20/40 or +0.30 logMAR (inclusive) with no eccentric viewing, and visual fields no better than 70 degrees in total in each eye.
* Are over the age of 18 (inclusive) and has full legal capacity to provide informed consent.
* Have read and fully comprehends the information in the consent letter.
* Are willing and capable of adhering to instructions and maintaining the outlined appointment schedule.
Exclusion Criteria
* Have been diagnosed with dementia or self-reported dementia with no formal diagnosis.
* Have been diagnosed with a cognitive impairment or self-reported cognitive impairment with no formal diagnosis.
* Have been diagnosed with physical or motor impairments resulting in walking and/or balancing issues or self-reported physical or motor impairments resulting in walking and/or balancing issues with no formal diagnosis.
* Have been diagnosed with vestibular disorders or dysfunctions which affects one's balance and/or mobility or self-reported vestibular disorders or dysfunctions which affects one's balance and/or mobility with no formal diagnosis.
* Are unable to follow the researcher's instructions.
* Are anticipating treatment (including ocular surgery) for any eye disease within the duration of the study.
* Have any ocular pathology in addition to retinitis pigmentosa (RP), rod-cone dystrophy, or advanced glaucoma, which can diminish their visual acuity and/or their visual field, however wearing glasses or contact lenses, as well as mild cataract of grade 2 or below is acceptable.
* Have severe hearing impairment.
* Are pregnant or trying to get pregnant.
* Fit any of the typical contraindicators for brain stimulation. See contraindicator section below.
For all participants the contraindications for brain stimulation are:
* Diagnosed with epilepsy or have previously experienced an epileptic seizure.
* Implanted medication pump or implanted electronic device, including defibrillator or pacemaker.
* Any metal implants in the head (excluding tooth fillings).
* Active electric implants anywhere in the body (especially the head region).
* On psychoactive medication for any psychiatric or neurological conditions including but not limited to depression and schizophrenia.
* Areas of sensitive skin located on the face or head, or a skin condition on the face, or regularly use medication to alleviate skin irritation on the face.
* Recurring headaches.
* Previous head injury or skull fracture or head/brain surgery.
* Heart disease, neurological condition, or a history of cardiac or neurological surgery.
* Current or historical cancerous or noncancerous brain tumor, or other abnormalities in brain structure.
18 Years
ALL
No
Sponsors
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University of Waterloo School of Optometry and Vision Science
UNKNOWN
The Hong Kong Polytechnic University
OTHER
University of Waterloo
OTHER
Responsible Party
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Ben Thompson
Director and Professor, School of Optometry and Vision Science.
Principal Investigators
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Benjamin Thompson, PhD
Role: PRINCIPAL_INVESTIGATOR
University of Waterloo School of Optometry and Vision Science
Locations
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University of Waterloo, School of Optometry and Vision Science
Waterloo, Ontario, Canada
Countries
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Central Contacts
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Provided Documents
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Document Type: Study Protocol
Document Type: Statistical Analysis Plan
Other Identifiers
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REB #47153
Identifier Type: -
Identifier Source: org_study_id
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