Retinitis PigmentosaSLAMNCT04359108
Environmental Localization Mapping and Guidance for Visual Prosthesis Users
A study testing Navigation system mode: Argus Vision, Navigation system mode: Depth Vision and Navigation system mode: Depth Vision with Haptic / Audio in people with Retinitis Pigmentosa and Visual Impairment, run by Johns Hopkins University at 2 sites in United States.
Trial summary
This study is driven by the hypothesis that independent navigation by blind users of visual prosthetic devices can be greatly aided by use of an autonomous navigational aid that provides information about the environment and guidance for navigation through multimodal sensory cues. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Retinitis Pigmentosa, Visual Impairment, Visual Prosthesis
- What is being tested?
- Navigation system mode: Argus Vision, Navigation system mode: Depth Vision and Navigation system mode: Depth Vision with Haptic / Audio
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 26 participants
- Where
- 2 sitesUnited States
- Study dates
- 16 Mar 2021to 30 Sep 2024
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
None listed.
Who cannot join
- Subject is unwilling or unable to travel to testing facility for at least 3 days of testing within a one-week timeframe;
- Subject does not speak English;
- Subject has language or hearing impairment.
Trial locations and contacts
2 sites in 1 country.
United States2 sites
Johns Hopkins Medicine - Wilmer Eye Institute
Baltimore, Maryland, 21205
Johns Hopkins Applied Physics Laboratory
Laurel, Maryland, 20723
About this study
This study is driven by the hypothesis that independent navigation by blind users of visual prosthetic devices can be greatly aided by use of an autonomous navigational aid that provides information about the environment and guidance for navigation through multimodal sensory cues. For this study, the investigators developed a navigation system that uses on-board sensing to map the user's environment and compute navigable paths to desired destinations in real-time. Information regarding obstacles and directional guidance is communicated to the user via a combination of sensory modalities including limited vision (through the user's visual prosthesis), haptic, and audio cues. This study evaluates how effectively this navigational aid improves prosthetic vision users' ability to perform navigational tasks. The participants for this study include both retinal prosthesis users of the Argus II Retinal Prosthesis System (Argus II) and normally sighted individuals who use a virtual reality headset to simulate the limited vision of the Argus II system.
Read the detailed description
About 1.3 million Americans aged 40 and older are legally blind, a majority because of diseases with onset later in life, such as glaucoma and age-related macular degeneration. Second Sight Medical Products (SSMP) has developed the world's first FDA approved retinal implant, Argus II, intended to restore some functional vision for people suffering from retinitis pigmentosa (RP).
In this era of smart devices, generic navigation technology, such as GPS mapping apps for smartphones, can provide directions to help guide a blind user from point A to point B. However, these navigational aids do little to enable blind users to form an egocentric understanding of the surroundings, are not suited to navigation indoors, and do nothing to assist in avoiding obstacles to mobility. The Argus II, on the other hand, provides blind users with a limited visual representation of the users surroundings that improves users' ability to orient themselves and traverse obstacles, yet lacks features for high-level navigation and semantic interpretation of the surroundings. The proposed study aims to address these limitations of the Argus II through a synergy of state-of-the-art simultaneous localization and mapping (SLAM) and scene recognition technologies.
This study is driven by the hypothesis that independent navigation by blind users of visual prosthetic devices can be greatly aided by use of an autonomous navigational aid that provides information about the environment and guidance for navigation through multimodal sensory cues. The investigators developed a navigation system that uses on-board sensing and SLAM-based algorithms to continuously construct a map of the user's environment and locate the user within that map in real-time. On-board path planning algorithms compute optimal navigation routes to reach desired destinations based on the constructed map. The system then communicates obstacle locations and navigational cues to the user while navigating via a combination of sensory modalities. The participants for this study include blind Argus II users, who use their retinal implant for vision, and normally sighted individuals, who use a virtual reality headset to simulate the limited vision of a retinal prosthesis.
The sensory modalities used by the navigational aid to communicate information back to the user include:
- Limited vision is provided via the user's visual prosthesis, with the Argus II retinal implant supporting an image size of 10 x 6 pixels spanning approximately 18 x 11 degrees field-of-view. Images sent to the visual implant are derived from video frames provided by forward-facing cameras integrated within headgear worn by the user. Three forms of vision feedback are evaluated in this study including: 1) the standard vision output of the Argus II (which uses texture-based processing including difference-of-Gaussian and contrast enhancement filters), 2) an enhanced depth-based vision mode that uses the depth sensing capabilities of the navigational aid to highlight above-ground obstacles, and 3) a high field of view depth-based vision mode that doubles the pixel size and field of view of the visual feedback in each dimension. The depth-vision modes display only above-ground obstacles with increasing brightness relative to decreasing distance from the user; the ground and obstacles beyond a threshold distance are not displayed in order to declutter the visual scene. The high field-of-view depth-vision mode is only utilized by normally sighted participants, as this mode exceeds the vision capabilities of the Argus II implant.
- Haptic cues indicate the direction in which the user should advance in order to follow the path computed by the navigational aid to reach a target destination. The haptic cues are generated by vibrators situated at five positions located left-to-right along the users forehead, which are built into user-worn headgear. The five vibration points indicate for the user to turn in directions: "far left", "slight left", "straight ahead", "slight right", and "far right".
- Audio cues provide an audible alert when the user approaches an obstacle within 1.5 feet and provide verbal updates on the remaining distance to reach the destination along the path computed by the navigational aid.
This study compares participants' performance in completing navigation tasks using five different modes and combinations of the foregoing sensory modalities as follows: 1) Argus vision, 2) depth vision, 3) depth vision with haptic and audio, 4) haptic and audio (without vision), and 5) high field-of-view depth vision.
The navigation tasks performed by the participants using these modalities include navigating through a dense obstacle field and navigating between rooms within an indoor facility that requires successful traversal of non-trivial paths.
In addition, a third experiment evaluates the effect of resolution and field-of-view of the retinal implant upon participants' ability to visually discern relative distances to different obstacles based on optical flow patterns induced by the participant's motion when approaching obstacles situated at different distances ahead of the user. For this experiment, the following four vision settings are evaluated: 1) low resolution / low field-of-view, 2) low resolution / high field-of-view, 3) high resolution / low field-of-view, and 4) high resolution / high field-of-view. The "low" settings correspond to the values of the Argus II system, whereas the "high" settings corresponding to a doubling of the "low" values along each dimension. For Argus user participants, only the low resolution / low field-of-view setting is evaluated since the Argus II retinal implant is incapable of supporting the higher vision settings.
- Conditions
- Retinitis Pigmentosa, Visual Impairment, Visual Prosthesis
- Being tested
- Navigation system mode: Argus Vision, Navigation system mode: Depth Vision, Navigation system mode: Depth Vision with Haptic / Audio, Navigation system mode: Haptic / Audio, Navigation system mode: High Field-of-View Depth Vision
- Keywords
- Retinal Prosthesis, Argus II
- Medical subject headings
- Retinitis Pigmentosa, Vision Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Navigation system mode: Argus VisionDevice
This intervention uses the navigational aid with the output sensory modalities configured as follows:
- Vision: Argus mode
- Haptics: none
- Audio: none Since this mode only provides the standard Argus vision, it is equivalent to using the base Argus II system without the navigational aid.
Navigation system mode: Depth VisionDevice
This intervention uses the navigational aid with the output sensory modalities configured as follows:
- Vision: Depth mode (at Argus II resolution and field-of-view)
- Haptics: none
- Audio: none
Navigation system mode: Depth Vision with Haptic / AudioDevice
This intervention uses the navigational aid with the output sensory modalities configured as follows:
- Vision: Depth mode (at Argus II resolution and field-of-view)
- Haptics: yes
- Audio: yes
Navigation system mode: Haptic / AudioDevice
This intervention uses the navigational aid with the output sensory modalities configured as follows:
- Vision: none
- Haptics: yes
- Audio: yes Since this mode does not provide any visual feedback, it is equivalent to using navigational aid completely blind without a visual prosthesis.
Navigation system mode: High Field-of-View Depth VisionDevice
This intervention uses the navigational aid with the output sensory modalities configured as follows:
- Vision: High Field-of-View Depth mode (at twice the Argus II resolution and field-of-view along each dimension)
- Haptics: none
- Audio: none
Distance test vision mode: Low Resolution / Low Field-of-ViewDevice
This intervention performs the relative distance to two obstacles test with the user's vision output configured as follows:
- Resolution: Low
- Field-of-View: Low
Distance test vision mode: Low Resolution / High Field-of-ViewDevice
This intervention performs the relative distance to two obstacles test with the user's vision output configured as follows:
- Resolution: Low
- Field-of-View: High
Distance test vision mode: High Resolution / Low Field-of-ViewDevice
This intervention performs the relative distance to two obstacles test with the user's vision output configured as follows:
- Resolution: High
- Field-of-View: Low
Distance test vision mode: High Resolution / High Field-of-ViewDevice
This intervention performs the relative distance to two obstacles test with the user's vision output configured as follows:
- Resolution: High
- Field-of-View: High
| Study group | Role | What they receive |
|---|---|---|
| Evaluation of normally sighted participants using a simulated visual prosthesis | Experimental | All normally sighted participants will be assigned to this arm of the study. This study group will perform all experiments using a virtual reality headset (Oculus Go) to simulate the limited vision of a retinal prosthesis system. This study group will include all interventions, including those that both match and exceed the visual performance of the Argus II system. Receives: Device: Navigation system mode: Argus Vision; Device: Navigation system mode: Depth Vision; Device: Navigation system mode: Depth Vision with Haptic / Audio; Device: Navigation system mode: Haptic / Audio; Device: Navigation system mode: High Field-of-View Depth Vision; Device: Distance test vision mode: Low Resolution / Low Field-of-View; Device: Distance test vision mode: Low Resolution / High Field-of-View; Device: Distance test vision mode: High Resolution / Low Field-of-View; Device: Distance test vision mode: High Resolution / High Field-of-View |
| Evaluation of blind participants using the Argus II retinal prosthesis | Experimental | All blind participants who have been implanted with the Argus II Retinal Prosthesis System will be assigned to this arm of the study. This study group will be limited to performing a subset of the interventions including only those that do not exceed the visual performance of the Argus II system. Receives: Device: Navigation system mode: Argus Vision; Device: Navigation system mode: Depth Vision; Device: Navigation system mode: Depth Vision with Haptic / Audio; Device: Navigation system mode: Haptic / Audio; Device: Distance test vision mode: Low Resolution / Low Field-of-View |
What is being measured
The primary outcome is the main question the study is designed to answer.
Duration of Time to Complete Navigational Tasks as Assessed by the Mean Duration of Travel in Seconds Normalized by the Nominal Path Distance in Meters
Participants will be asked to complete the navigation tasks of crossing an obstacle field approximately 6 meters in length and navigating to a target destination located about 20 - 30 meters away. The normalized duration of time to complete each navigation task will be measured in seconds. To account for variability in the path distances of different trials, the measured time will be normalized by a reference (nominal) path distance in meters associated with the configuration of each trial. The mean normalized time across all trials will be computed for each intervention.
Measured: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Distance Traversed to Complete Navigational Tasks as Assessed by the Mean Distance Traveled in Meters Normalized by the Nominal Path Distance in Meters
Participants will be asked to complete the navigation tasks of crossing an obstacle field approximately 6 meters in length and navigating to a target destination located about 20 - 30 meters away. The normalized distance traversed to complete each navigation task will be measured. To account for variability in the path distances of different trials, the measured distance will be normalized by a reference (nominal) path distance in meters associated with the configuration of each trial. The mean normalized distance across all trials will be computed for each intervention.
Measured: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Obstacle Avoidance While Completing Navigational Tasks as Assessed by the Mean Number of Contacts With Obstacles Normalized by the Nominal Path Distance in Meters
Participants will be asked to complete the navigation tasks of crossing an obstacle field approximately 6 meters in length and navigating to a target destination located about 20 - 30 meters away. The number of contacts with obstacles encountered while completing each navigation task will be measured. To account for variability in the path distances of different trials, the number of contacts will be normalized by a reference (nominal) path distance in meters associated with the configuration of each trial. The mean normalized number of contacts with obstacles across all trials will be computed for each intervention.
Measured: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Success in Completing Navigational Tasks as Assessed by the Mean Percentage of Trials Where Participants Successfully Reached the Intended Destination
Participants will be asked to navigate to a target destination located about 20 - 30 meters away. We will measure success rate as the mean number of trials for which each participants successfully reached the intended destination divided by the total number of trials performed by that participant for each intervention.
Measured: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Accuracy of Relative Distance Judgments as Assessed by the Percentage of Correct Responses
Participants will be presented with two physical objects and asked to identify which of the objects is the nearer one after walking a controlled distance down a centerline oriented between the objects. We will measure accuracy as the percentage of correct responses (the total number of correct responses divided by the total number of trials times 100).
Measured: Up to 60 seconds for each discrimination task, on Day 1 or Day 2
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Apr 2020
- Study start16 Mar 2021
- Primary completion30 Sep 2024
- Study completion30 Sep 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Retinitis PigmentosaStudies of the same condition, open and under way.
- More trials run by Johns Hopkins UniversityThe sponsor's other registered studies.
- 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
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 26 participants (actual)
Sponsor and investigators
- Lead sponsor
- Johns Hopkins University
- Sponsor type
- University, hospital or other
- Collaborators
- Carnegie Mellon University, National Eye Institute (NEI)
- Responsible party
- Sponsor
- Investigators
- Seth Billings, Ph.D., Principal investigator, Johns Hopkins University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04359108
- Sponsor's protocol ID
- IRB00228932
- Other IDs
- 1R01EY029741-01A1
- Acronym
- SLAM
- Status last verified
- Feb 2025
- First submitted
- 21 Apr 2020
- Last updated
- 10 Mar 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- No: Results from this study will be disseminated through conference presentations and peer-reviewed publications. However, IPD will not be shared outside the study team.
Publications
Christie B, Acosta NN, Sadeghi R, Kartha A, Ewulum C, Caspi A, Tenore FV, Dagnelie G, Klatzky RL, Billings SD. Autonomous multisensory enhancement of a visual neuroprosthesis for navigation: technical proof-of-concept with simulated prosthetic vision and single-subject case study of a visual prosthesis user. J Neural Eng. 2026 Feb 5;23(1). doi: 10.1088/1741-2552/ae3d67.
PubMed 41587489
Study at a glance
From the registry record, last updated by the sponsor on 10 Mar 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Environmental Localization Mapping and Guidance for Visual Prosthesis Users
- ClinicalTrials.gov ID
- NCT04359108
- Acronym / sponsor ID
- SLAM / IRB00228932
- Conditions
- Retinitis Pigmentosa, Visual Impairment, Visual Prosthesis
- Keywords
- Retinal Prosthesis, Argus II
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 26 participants (actual)
- Lead sponsor
- Johns Hopkins UniversityUniversity, hospital or other
- Collaborators
- Carnegie Mellon University, National Eye Institute (NEI)
- Study start
- 16 Mar 2021 (actual)
- Primary completion
- 30 Sep 2024 (actual)
- Study completion
- 30 Sep 2024 (actual)
- First posted
- 24 Apr 2020 (actual)
- Results
- Posted 10 Mar 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is driven by the hypothesis that independent navigation by blind users of visual prosthetic devices can be greatly aided by use of an autonomous navigational aid that provides information about the environment and guidance for navigation through multimodal sensory cues. For this study, the investigators developed a navigation system that uses on-board sensing to map the user's environment and compute navigable paths to desired destinations in real-time. Information regarding obstacles and directional guidance is communicated to the user via a combination of sensory modalities including limited vision (through the user's visual prosthesis), haptic, and audio cues. This study evaluates how effectively this navigational aid improves prosthetic vision users' ability to perform navigational tasks. The participants for this study include both retinal prosthesis users of the Argus II Retinal Prosthesis System (Argus II) and normally sighted individuals who use a virtual reality headset to simulate the limited vision of the Argus II system.
Detailed description
About 1.3 million Americans aged 40 and older are legally blind, a majority because of diseases with onset later in life, such as glaucoma and age-related macular degeneration. Second Sight Medical Products (SSMP) has developed the world's first FDA approved retinal implant, Argus II, intended to restore some functional vision for people suffering from retinitis pigmentosa (RP).
In this era of smart devices, generic navigation technology, such as GPS mapping apps for smartphones, can provide directions to help guide a blind user from point A to point B. However, these navigational aids do little to enable blind users to form an egocentric understanding of the surroundings, are not suited to navigation indoors, and do nothing to assist in avoiding obstacles to mobility. The Argus II, on the other hand, provides blind users with a limited visual representation of the users surroundings that improves users' ability to orient themselves and traverse obstacles, yet lacks features for high-level navigation and semantic interpretation of the surroundings. The proposed study aims to address these limitations of the Argus II through a synergy of state-of-the-art simultaneous localization and mapping (SLAM) and scene recognition technologies.
This study is driven by the hypothesis that independent navigation by blind users of visual prosthetic devices can be greatly aided by use of an autonomous navigational aid that provides information about the environment and guidance for navigation through multimodal sensory cues. The investigators developed a navigation system that uses on-board sensing and SLAM-based algorithms to continuously construct a map of the user's environment and locate the user within that map in real-time. On-board path planning algorithms compute optimal navigation routes to reach desired destinations based on the constructed map. The system then communicates obstacle locations and navigational cues to the user while navigating via a combination of sensory modalities. The participants for this study include blind Argus II users, who use their retinal implant for vision, and normally sighted individuals, who use a virtual reality headset to simulate the limited vision of a retinal prosthesis.
The sensory modalities used by the navigational aid to communicate information back to the user include:
- Limited vision is provided via the user's visual prosthesis, with the Argus II retinal implant supporting an image size of 10 x 6 pixels spanning approximately 18 x 11 degrees field-of-view. Images sent to the visual implant are derived from video frames provided by forward-facing cameras integrated within headgear worn by the user. Three forms of vision feedback are evaluated in this study including: 1) the standard vision output of the Argus II (which uses texture-based processing including difference-of-Gaussian and contrast enhancement filters), 2) an enhanced depth-based vision mode that uses the depth sensing capabilities of the navigational aid to highlight above-ground obstacles, and 3) a high field of view depth-based vision mode that doubles the pixel size and field of view of the visual feedback in each dimension. The depth-vision modes display only above-ground obstacles with increasing brightness relative to decreasing distance from the user; the ground and obstacles beyond a threshold distance are not displayed in order to declutter the visual scene. The high field-of-view depth-vision mode is only utilized by normally sighted participants, as this mode exceeds the vision capabilities of the Argus II implant.
- Haptic cues indicate the direction in which the user should advance in order to follow the path computed by the navigational aid to reach a target destination. The haptic cues are generated by vibrators situated at five positions located left-to-right along the users forehead, which are built into user-worn headgear. The five vibration points indicate for the user to turn in directions: "far left", "slight left", "straight ahead", "slight right", and "far right".
- Audio cues provide an audible alert when the user approaches an obstacle within 1.5 feet and provide verbal updates on the remaining distance to reach the destination along the path computed by the navigational aid.
This study compares participants' performance in completing navigation tasks using five different modes and combinations of the foregoing sensory modalities as follows: 1) Argus vision, 2) depth vision, 3) depth vision with haptic and audio, 4) haptic and audio (without vision), and 5) high field-of-view depth vision.
The navigation tasks performed by the participants using these modalities include navigating through a dense obstacle field and navigating between rooms within an indoor facility that requires successful traversal of non-trivial paths.
In addition, a third experiment evaluates the effect of resolution and field-of-view of the retinal implant upon participants' ability to visually discern relative distances to different obstacles based on optical flow patterns induced by the participant's motion when approaching obstacles situated at different distances ahead of the user. For this experiment, the following four vision settings are evaluated: 1) low resolution / low field-of-view, 2) low resolution / high field-of-view, 3) high resolution / low field-of-view, and 4) high resolution / high field-of-view. The "low" settings correspond to the values of the Argus II system, whereas the "high" settings corresponding to a doubling of the "low" values along each dimension. For Argus user participants, only the low resolution / low field-of-view setting is evaluated since the Argus II retinal implant is incapable of supporting the higher vision settings.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Evaluation of normally sighted participants using a simulated visual prosthesis | Experimental | Device: Navigation system mode: Argus Vision, Device: Navigation system mode: Depth Vision, Device: Navigation system mode: Depth Vision with Haptic / Audio, Device: Navigation system mode: Haptic / Audio, Device: Navigation system mode: High Field-of-View Depth Vision, Device: Distance test vision mode: Low Resolution / Low Field-of-View, Device: Distance test vision mode: Low Resolution / High Field-of-View, Device: Distance test vision mode: High Resolution / Low Field-of-View, Device: Distance test vision mode: High Resolution / High Field-of-ViewAll normally sighted participants will be assigned to this arm of the study. This study group will perform all experiments using a virtual reality headset (Oculus Go) to simulate the limited vision of a retinal prosthesis system. This study group will include all interventions, including those that both match and exceed the visual performance of the Argus II system. |
| Evaluation of blind participants using the Argus II retinal prosthesis | Experimental | Device: Navigation system mode: Argus Vision, Device: Navigation system mode: Depth Vision, Device: Navigation system mode: Depth Vision with Haptic / Audio, Device: Navigation system mode: Haptic / Audio, Device: Distance test vision mode: Low Resolution / Low Field-of-ViewAll blind participants who have been implanted with the Argus II Retinal Prosthesis System will be assigned to this arm of the study. This study group will be limited to performing a subset of the interventions including only those that do not exceed the visual performance of the Argus II system. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (0 listed)
Key exclusion criteria (3 listed)
- Subject is unwilling or unable to travel to testing facility for at least 3 days of testing within a one-week timeframe;
- Subject does not speak English;
- Subject has language or hearing impairment.
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 |
|---|---|---|
| Navigation system mode: Argus VisionThis intervention uses the navigational aid with the output sensory modalities configured as follows: * Vision: Argus mode * Haptics: none * Audio: none Since this mode only provides the standard Argus vision, it is equivalent to using the base Argus II system without the navigational aid. | Device | Evaluation of blind participants using the Argus II retinal prosthesis, Evaluation of normally sighted participants using a simulated visual prosthesis |
| Navigation system mode: Depth VisionThis intervention uses the navigational aid with the output sensory modalities configured as follows: * Vision: Depth mode (at Argus II resolution and field-of-view) * Haptics: none * Audio: none | Device | Evaluation of blind participants using the Argus II retinal prosthesis, Evaluation of normally sighted participants using a simulated visual prosthesis |
| Navigation system mode: Depth Vision with Haptic / AudioThis intervention uses the navigational aid with the output sensory modalities configured as follows: * Vision: Depth mode (at Argus II resolution and field-of-view) * Haptics: yes * Audio: yes | Device | Evaluation of blind participants using the Argus II retinal prosthesis, Evaluation of normally sighted participants using a simulated visual prosthesis |
| Navigation system mode: Haptic / AudioThis intervention uses the navigational aid with the output sensory modalities configured as follows: * Vision: none * Haptics: yes * Audio: yes Since this mode does not provide any visual feedback, it is equivalent to using navigational aid completely blind without a visual prosthesis. | Device | Evaluation of blind participants using the Argus II retinal prosthesis, Evaluation of normally sighted participants using a simulated visual prosthesis |
| Navigation system mode: High Field-of-View Depth VisionThis intervention uses the navigational aid with the output sensory modalities configured as follows: * Vision: High Field-of-View Depth mode (at twice the Argus II resolution and field-of-view along each dimension) * Haptics: none * Audio: none | Device | Evaluation of normally sighted participants using a simulated visual prosthesis |
| Distance test vision mode: Low Resolution / Low Field-of-ViewThis intervention performs the relative distance to two obstacles test with the user's vision output configured as follows: * Resolution: Low * Field-of-View: Low | Device | Evaluation of blind participants using the Argus II retinal prosthesis, Evaluation of normally sighted participants using a simulated visual prosthesis |
| Distance test vision mode: Low Resolution / High Field-of-ViewThis intervention performs the relative distance to two obstacles test with the user's vision output configured as follows: * Resolution: Low * Field-of-View: High | Device | Evaluation of normally sighted participants using a simulated visual prosthesis |
| Distance test vision mode: High Resolution / Low Field-of-ViewThis intervention performs the relative distance to two obstacles test with the user's vision output configured as follows: * Resolution: High * Field-of-View: Low | Device | Evaluation of normally sighted participants using a simulated visual prosthesis |
| Distance test vision mode: High Resolution / High Field-of-ViewThis intervention performs the relative distance to two obstacles test with the user's vision output configured as follows: * Resolution: High * Field-of-View: High | Device | Evaluation of normally sighted participants using a simulated visual prosthesis |
Primary outcome
Duration of Time to Complete Navigational Tasks as Assessed by the Mean Duration of Travel in Seconds Normalized by the Nominal Path Distance in Meters
Time frame: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Participants will be asked to complete the navigation tasks of crossing an obstacle field approximately 6 meters in length and navigating to a target destination located about 20 - 30 meters away. The normalized duration of time to complete each navigation task will be measured in seconds. To account for variability in the path distances of different trials, the measured time will be normalized by a reference (nominal) path distance in meters associated with the configuration of each trial. The mean normalized time across all trials will be computed for each intervention.
Distance Traversed to Complete Navigational Tasks as Assessed by the Mean Distance Traveled in Meters Normalized by the Nominal Path Distance in Meters
Time frame: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Participants will be asked to complete the navigation tasks of crossing an obstacle field approximately 6 meters in length and navigating to a target destination located about 20 - 30 meters away. The normalized distance traversed to complete each navigation task will be measured. To account for variability in the path distances of different trials, the measured distance will be normalized by a reference (nominal) path distance in meters associated with the configuration of each trial. The mean normalized distance across all trials will be computed for each intervention.
Obstacle Avoidance While Completing Navigational Tasks as Assessed by the Mean Number of Contacts With Obstacles Normalized by the Nominal Path Distance in Meters
Time frame: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Participants will be asked to complete the navigation tasks of crossing an obstacle field approximately 6 meters in length and navigating to a target destination located about 20 - 30 meters away. The number of contacts with obstacles encountered while completing each navigation task will be measured. To account for variability in the path distances of different trials, the number of contacts will be normalized by a reference (nominal) path distance in meters associated with the configuration of each trial. The mean normalized number of contacts with obstacles across all trials will be computed for each intervention.
Success in Completing Navigational Tasks as Assessed by the Mean Percentage of Trials Where Participants Successfully Reached the Intended Destination
Time frame: Up to 7 minutes for each navigation task, on Day 1 or Day 2
Participants will be asked to navigate to a target destination located about 20 - 30 meters away. We will measure success rate as the mean number of trials for which each participants successfully reached the intended destination divided by the total number of trials performed by that participant for each intervention.
Accuracy of Relative Distance Judgments as Assessed by the Percentage of Correct Responses
Time frame: Up to 60 seconds for each discrimination task, on Day 1 or Day 2
Participants will be presented with two physical objects and asked to identify which of the objects is the nearer one after walking a controlled distance down a centerline oriented between the objects. We will measure accuracy as the percentage of correct responses (the total number of correct responses divided by the total number of trials times 100).
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Mar 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 41587489Christie B, Acosta NN, Sadeghi R, Kartha A, Ewulum C, Caspi A, Tenore FV, Dagnelie G, Klatzky RL, Billings SD. Autonomous multisensory enhancement of a visual neuroprosthesis for navigation: technical proof-of-concept with simulated prosthetic vision and single-subject case study of a visual prosthesis user. J Neural Eng. 2026 Feb 5;23(1). doi: 10.1088/1741-2552/ae3d67.
- Individual participant dataSharing planned: No. Results from this study will be disseminated through conference presentations and peer-reviewed publications. However, IPD will not be shared outside the study 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. This study is not recruiting at the moment.
Seth Billings, Ph.D. principal investigator
Johns Hopkins University
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Navigation system mode: Argus Vision, Navigation system mode: Depth Vision and Navigation system mode: Depth Vision with Haptic / Audio in people with Retinitis Pigmentosa and Visual Impairment, run by Johns Hopkins University at 2 sites in United States.
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 0 inclusion and 3 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: finished, as of the sponsor's last update on 10 Mar 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in United States. 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?
Yes. Results are posted in the registry (first posted 10 Mar 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Duration of Time to Complete Navigational Tasks as Assessed by the Mean Duration of Travel in Seconds Normalized by the Nominal Path Distance in Meters (time frame: Up to 7 minutes for each navigation task, on Day 1 or Day 2). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04359108, which also lists 1 linked publication.
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 10 Mar 2025.