An interventional study of Navigation system mode: Argus Vision and Navigation system mode: Depth Vision in Retinitis Pigmentosa, Visual Impairment and Visual Prosthesis, sponsored by Johns Hopkins University. Completed at 2 sites in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-03-10.
Sponsored by Johns Hopkins University · Not applicable, Interventional, and Basic science
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.
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:
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.
278 studies on the registry are indexed under Retinitis Pigmentosa; 72 are open to participants now.
This study's enrollment of 26 is close to the median of 27 across 179 interventional studies indexed under Retinitis Pigmentosa.
Browse Retinitis Pigmentosa studies →Johns Hopkins University is the lead sponsor of 1,815 studies on the registry; 315 are open to participants now.
Of its 208 completed or terminated interventional studies of FDA-regulated products, 144 (69%) have results posted.
Counted across the registry records on this site, refreshed daily.
Criteria for inclusion of normally sighted individuals:
Criteria for inclusion of Argus II users:
The inclusion criteria for the study are the following:
Exclusion criteria for all subjects is the following:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
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
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.
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
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.
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
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
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.
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
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
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
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
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
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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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).
Time frame: Up to 60 seconds for each discrimination task, on Day 1 or Day 2
For blind participants, 6 individuals who had previously received the Argus II retinal implant were recruited. For sighted participants, 20 individuals with normal vision were recruited from staff members of the Johns Hopkins University Applied Physics Laboratory.
| Milestone | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis |
|---|---|---|
| Started | 20 | 6 |
| Completed | 19 | 1 |
| Not completed | 1 | 5 |
| Withdrew: Withdrawal by subject | 1 | 0 |
| Withdrew: Unable or too feeble to walk independently | 0 | 2 |
| Withdrew: Argus ii system stopped functioning | 0 | 1 |
| Withdrew: Died of natural causes unrelated to the study before study ended | 0 | 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.
| seconds/meter | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis |
|---|---|---|
| Obstacle Field Test: Argus Vision | 14.54 ± 1.03 | 14.09 ± 2.19 |
| Obstacle Field Test: Depth Vision | 10.46 ± 0.93 | 14.60 ± 2.17 |
| Obstacle Field Test: Depth Vision + Haptic/Audio | 9.38 ± 0.80 | 14.05 ± 1.31 |
| Obstacle Field Test: Haptic/Audio | 9.72 ± 0.83 | 9.13 ± 1.29 |
| Obstacle Field Test: High Field-of-View Depth Vision | 7.54 ± 0.68 | NA ± NA |
| Navigate to Destination Test: Argus Vision | 9.32 ± 0.94 | NA ± NA |
| Navigate to Destination Test: Depth Vision | 8.68 ± 0.81 | 5.11 ± NA |
| Navigate to Destination Test: Depth Vision + Haptic/Audio | 7.05 ± 0.44 | 7.95 ± 1.70 |
| Navigate to Destination Test: Haptic/Audio | 7.05 ± 0.49 | 9.31 ± 1.75 |
| Navigate to Destination Test: High Field-of-View Depth Vision | 6.37 ± 0.59 | NA ± NA |
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.
| meters/meter | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis |
|---|---|---|
| Obstacle Field Test: Argus Vision | 1.598 ± 0.045 | 1.543 ± 0.048 |
| Obstacle Field Test: Depth Vision | 1.305 ± 0.027 | 1.427 ± 0.126 |
| Obstacle Field Test: Depth Vision + Haptic/Audio | 1.227 ± 0.018 | 1.537 ± 0.125 |
| Obstacle Field Test: Haptic/Audio | 1.230 ± 0.026 | 1.300 ± 0.095 |
| Obstacle Field Test: High Field-of-View Depth Vision | 1.217 ± 0.025 | NA ± NA |
| Navigate to Destination Test: Argus Vision | 1.236 ± 0.095 | NA ± NA |
| Navigate to Destination Test: Depth Vision | 1.315 ± 0.075 | 1.1 ± NA |
| Navigate to Destination Test: Depth Vision + Haptic/Audio | 1.130 ± 0.034 | 1.505 ± 0.245 |
| Navigate to Destination Test: Haptic/Audio | 1.138 ± 0.035 | 1.735 ± 0.205 |
| Navigate to Destination Test: High Field-of-View Depth Vision | 1.196 ± 0.072 | NA ± NA |
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.
| number of contacts / meter | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis |
|---|---|---|
| Obstacle Field Test: Argus Vision | 0.737 ± 0.060 | 0.523 ± 0.101 |
| Obstacle Field Test: Depth Vision | 0.224 ± 0.039 | 0.465 ± 0.058 |
| Obstacle Field Test: Depth Vision + Haptic/Audio | 0.201 ± 0.025 | 0.175 ± 0.101 |
| Obstacle Field Test: Haptic/Audio | 0.250 ± 0.035 | 0.116 ± 0.116 |
| Obstacle Field Test: High Field-of-View Depth Vision | 0.090 ± 0.029 | NA ± NA |
| Navigate to Destination Test: Argus Vision | 0.407 ± 0.057 | NA ± NA |
| Navigate to Destination Test: Depth Vision | 0.257 ± 0.055 | 0.297 ± NA |
| Navigate to Destination Test: Depth Vision + Haptic/Audio | 0.130 ± 0.017 | 0.054 ± 0.013 |
| Navigate to Destination Test: Haptic/Audio | 0.151 ± 0.016 | 0.061 ± 0.006 |
| Navigate to Destination Test: High Field-of-View Depth Vision | 0.162 ± 0.035 | NA ± NA |
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.
| percentage of trials | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis |
|---|---|---|
| Argus Vision | 50.0 ± 8.9 | 0 ± NA |
| Depth Vision | 65.7 ± 8.6 | 50 ± NA |
| Depth Vision + Haptic / Audio | 97.5 ± 2.5 | 100 ± NA |
| Haptic / Audio | 92.5 ± 4.1 | 100 ± NA |
| High Field of View Depth Vision | 72.5 ± 7.7 | 100 ± NA |
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).
| percentage of correct responses | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis |
|---|---|---|
| Low Resolution / Low Field-of-View | 62 ± 3.4 | 83 ± NA |
| Low Resolution / High Field-of-View | 72.2 ± 3.9 | NA ± NA |
| High Resolution / Low Field-of-View | 67.8 ± 4.4 | NA ± NA |
| High Resolution / High Field-of-View | 75.6 ± 2.9 | NA ± NA |
Collected over Up to 2 days. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | 0/20 (0%) | 0/20 (0%) | 0/20 (0%) |
| Evaluation of Blind Participants Using the Argus II Retinal Prosthesis | 2/6 (33.3%) | 0/6 (0%) | 0/6 (0%) |
| Age, Categorical(Participants) | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis | Total |
|---|---|---|---|
| <=18 years | 0 | 0 | 0 |
| Between 18 and 65 years | 19 | 2 | 21 |
| >=65 years | 1 | 4 | 5 |
| Sex: Female, Male(Participants) | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis | Total |
|---|---|---|---|
| Female | 6 | 2 | 8 |
| Male | 14 | 4 | 18 |
| Ethnicity (NIH/OMB)(Participants) | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis | Total |
|---|---|---|---|
| Hispanic or Latino | 0 | 0 | 0 |
| Not Hispanic or Latino | 12 | 6 | 18 |
| Unknown or Not Reported | 8 | 0 | 8 |
| Race (NIH/OMB)(Participants) | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 3 | 0 | 3 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 |
| Black or African American | 1 | 0 | 1 |
| White | 9 | 6 | 15 |
| More than one race | 2 | 0 | 2 |
| Unknown or Not Reported | 5 | 0 | 5 |
| Region of Enrollment(Participants) | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis | Total |
|---|---|---|---|
| United States | 20 | 6 | 26 |
| Vision Impairment(Participants) | Evaluation of Normally Sighted Participants Using a Simulated Visual Prosthesis | Evaluation of Blind Participants Using the Argus II Retinal Prosthesis | Total |
|---|---|---|---|
| Normal Vision | 20 | 0 | 20 |
| Blind having Argus II Implant | 0 | 6 | 6 |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: 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.
Ran from Mar 2021 to primary completion in Sep 2024, 42 months.
Results were first posted in Mar 2025, 5 months after primary completion.
Of 30 interventional studies with no phase under Retinitis Pigmentosa, half reached primary completion within 42 months of starting (the median), counting those still running; a quarter within 21 and three quarters within 154. This study's 42 months is close to that.
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