Retinitis PigmentosaNCT05285618

The Perceptual Experience of Argus II Users

A study testing Argus II in people with Retinitis Pigmentosa, run by University of California, Santa Barbara at 3 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

Who is it for?: Ages 18 years and olderHealthy volunteers can take part
Conditions the study is for: Retinitis Pigmentosa
What is being tested?: Argus II
Type of treatment: Medical device
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 6 participants
Where: 3 sitesUnited States
Study dates: 11 Jan 2022to 31 Aug 2023
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

Subject must be at least 25 years of age;
Subject has been implanted with the Argus II system;
Subject's eye has healed from surgery and the surgeon has cleared the subject for programming;
Subject has the cognitive and communication ability to participate in the study (i.e., follow spoken directions, perform tests, and give feedback);
Subject is willing to conduct psychophysics testing up to 4-6 hours per day of testing on 3-5 consecutive days;
Subject is capable of understanding patient information materials and giving written informed consent;
Subject is able to walk unassisted.

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;
Sighted controls: Subject has a history of motion sickness or flicker vertigo
Subject does not speak English;
Subject has language or hearing impairment

Trial locations and contacts

3 sites in 1 country.

United States3 sites

University of Michigan, Ann Arbor
Ann Arbor, Michigan, 48109
Johns Hopkins University
Baltimore, Maryland, 21287
University of California, Santa Barbara
Santa Barbara, California, 93106

Other trials in United States

About this study

Official title: Predicting the Perceptual Experience of Argus II Retinal Prosthesis System Users

This Basic Experimental Studies Involving Humans (BESH) study investigates phosphene perception and performance factors in blind participants implanted with the Argus II retinal prosthesis system. Using paired-electrode stimulation, we analyze how phosphene shape and number are influenced by neuroanatomical factors, stimulus parameters, and spatial offsets. Additionally, we examine the causes of high current thresholds and limited spatial resolution, which impede pattern vision in Argus II devices. This research aims to provide insights for optimizing stimulation strategies and improving retinal prosthesis design.

Read the detailed description

This study focuses on two experiments involving blind participants implanted with the Argus II retinal prosthesis:

Experiment 1: Paired-Electrode Phosphene Perception The study retrospectively analyzes 3548 phosphene drawings made by three participants. We investigate the impact of single- and paired-electrode stimulation on phosphene shape (area, perimeter, major/minor axis length) and the number of perceived phosphenes. Neuroanatomical parameters, including electrode-retina distance, electrode-fovea distance, and electrode-electrode distance (both along-axon and between-axon), are correlated with these outcomes. Statistical analyses include linear regression and partial correlation to examine the relationship between stimulation parameters and phosphene perception.

Experiment 2: Performance Factors in Argus II Prostheses This study explores the factors contributing to high current amplitude thresholds and poor spatial resolution in three participants. We measure current amplitude thresholds and two-point discrimination (the ability to distinguish stimulation on one versus two electrodes). Data from psychophysical experiments and simulations are analyzed to identify the roles of axonal stimulation, electrode lift, and retinal damage in limiting device performance.

These experiments aim to advance the understanding of epiretinal stimulation and inform the development of future retinal prostheses with improved spatial resolution and sensitivity.

Conditions: Retinitis Pigmentosa
Being tested: Argus II
Medical subject headings: Retinitis Pigmentosa

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Argus IIDevice
Participants used the Argus II retinal prosthesis system in both experiments to perform visual perception tasks.

Study groups in NCT05285618
Study group	Role	What they receive
Argus II users	Experimental	This Basic Experimental Studies Involving Humans (BESH) study investigates phosphene perception and performance factors in blind participants implanted with the Argus II retinal prosthesis system. Using paired-electrode stimulation, we analyze how phosphene shape and number are influenced by neuroanatomical factors, stimulus parameters, and spatial offsets. Additionally, we examine the causes of high current thresholds and limited spatial resolution, which impede pattern vision in Argus II devices. This research aims to provide insights for optimizing stimulation strategies and improving retinal prosthesis design. Receives: Device: Argus II

What is being measured

The primary outcome is the main question the study is designed to answer.

Number of Phosphenes Perceived
Number of phosphenes perceived in response to paired-electrode stimulation across 5 spatial distances and 7 temporal interpulse delays. Phosphenes are brief sensations of light or visual flashes that occur in the absence of an external light source. A response is counted as a phosphene if the participant reports any visual sensation consistent with a flash of light.
Measured: during single-session testing

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

11 Jan 202231 Aug 2023

First posted17 Mar 2022
Study start11 Jan 2022
Primary completion31 Aug 2023
Study completion31 Aug 2023

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 (2)Papers the sponsor has linked to this study.
Other trials for Retinitis PigmentosaStudies 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: Basic science
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Enrolment: 6 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT05285618
Sponsor's protocol ID: R00EY029329
Other IDs: R00EY029329
Status last verified: Dec 2024
First submitted: 4 Feb 2022
Last updated: 1 Jan 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: Yes
Individual data sharing: Yes: Deidentified data will be available from the investigative team, following initial publication of the results

Publications

Yucel EI, Sadeghi R, Kartha A, Montezuma SR, Dagnelie G, Rokem A, Boynton GM, Fine I, Beyeler M. Factors affecting two-point discrimination in Argus II patients. Front Neurosci. 2022 Aug 24;16:901337. doi: 10.3389/fnins.2022.901337. eCollection 2022.
PubMed 36090266
Hou Y, Nanduri D, Granley J, Weiland JD, Beyeler M. Axonal stimulation affects the linear summation of single-point perception in three Argus II users. J Neural Eng. 2024 Apr 8;21(2):026031. doi: 10.1088/1741-2552/ad31c4.
PubMed 38457841

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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Study at a glance

From the registry record, last updated by the sponsor on 1 Jan 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Predicting the Perceptual Experience of Argus II Retinal Prosthesis System Users
ClinicalTrials.gov ID: NCT05285618
Acronym / sponsor ID: R00EY029329
Conditions: Retinitis Pigmentosa
Study type: Interventional
Recruitment status: Completed
Enrolment: 6 participants (actual)
Lead sponsor: University of California, Santa BarbaraUniversity, hospital or other
Collaborators: Johns Hopkins University, University of Michigan, National Eye Institute (NEI)
Study start: 11 Jan 2022 (actual)
Primary completion: 31 Aug 2023 (actual)
Study completion: 31 Aug 2023 (actual)
First posted: 17 Mar 2022 (actual)
Results: Posted 1 Jan 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

This study focuses on two experiments involving blind participants implanted with the Argus II retinal prosthesis:

These experiments aim to advance the understanding of epiretinal stimulation and inform the development of future retinal prostheses with improved spatial resolution and sensitivity.

Study design

Primary purpose: Basic science
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Number of arms: 1

Arm	Type	Receives
Argus II users	Experimental	Device: Argus IIThis Basic Experimental Studies Involving Humans (BESH) study investigates phosphene perception and performance factors in blind participants implanted with the Argus II retinal prosthesis system. Using paired-electrode stimulation, we analyze how phosphene shape and number are influenced by neuroanatomical factors, stimulus parameters, and spatial offsets. Additionally, we examine the causes of high current thresholds and limited spatial resolution, which impede pattern vision in Argus II devices. This research aims to provide insights for optimizing stimulation strategies and improving retinal prosthesis design.

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Accepted
Age groups: Adult, Older adult

Key inclusion criteria (7 listed)

Subject must be at least 25 years of age;
Subject has been implanted with the Argus II system;
Subject's eye has healed from surgery and the surgeon has cleared the subject for programming;
Subject has the cognitive and communication ability to participate in the study (i.e., follow spoken directions, perform tests, and give feedback);
Subject is willing to conduct psychophysics testing up to 4-6 hours per day of testing on 3-5 consecutive days;

Key exclusion criteria (4 listed)

Subject is unwilling or unable to travel to testing facility for at least 3 days of testing within a one-week timeframe;
Sighted controls: Subject has a history of motion sickness or flicker vertigo
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
Argus IIParticipants used the Argus II retinal prosthesis system in both experiments to perform visual perception tasks.	Device	Argus II users

Primary outcome

Number of Phosphenes Perceived
Time frame: during single-session testing
Number of phosphenes perceived in response to paired-electrode stimulation across 5 spatial distances and 7 temporal interpulse delays. Phosphenes are brief sensations of light or visual flashes that occur in the absence of an external light source. A response is counted as a phosphene if the participant reports any visual sensation consistent with a flash of light.

Results and safety

Results posted to the registry on 1 Jan 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Argus II Users	6	6

Primary outcome: Number of Phosphenes Perceived

Time frame: during single-session testing. Mean (Standard Deviation). Unit: number of phosphenes

Measure	Argus II Users n = 6
Delay 0	1.09 (0.910)
Delay 4ms	1.43 (0.555)
Delay 12ms	1.46 (0.538)
Delay 29ms	1.41 (0.570)
Delay 50ms	1.48 (0.511)
Delay 178ms	1.37 (0.544)
Delay 419ms	1.36 (0.639)
Distance (808 - 1834um)	1.24 (0.642)

Argus II Users: p = 0.002, Mixed Models Analysis

Population analysed: Data were collected in 6 participants ranging in age from 45 to 88 years old. One participant was female. All identified as white, non-hispanic.

Adverse events

Time frame: 1 day. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Argus II Users	0 of 6 (0%)	0 of 6 (0%)	0 of 6

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 1 Jan 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Results publication: PubMed 36090266Yucel EI, Sadeghi R, Kartha A, Montezuma SR, Dagnelie G, Rokem A, Boynton GM, Fine I, Beyeler M. Factors affecting two-point discrimination in Argus II patients. Front Neurosci. 2022 Aug 24;16:901337. doi: 10.3389/fnins.2022.901337. eCollection 2022.
Results publication: PubMed 38457841Hou Y, Nanduri D, Granley J, Weiland JD, Beyeler M. Axonal stimulation affects the linear summation of single-point perception in three Argus II users. J Neural Eng. 2024 Apr 8;21(2):026031. doi: 10.1088/1741-2552/ad31c4.
Individual participant dataSharing planned: Yes. Deidentified data will be available from the investigative team, following initial publication of the results

Related trials for Retinitis Pigmentosa

RecruitingObservational study
Rod and Cone Mediated Function in Retinal Disease
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RecruitingObservational study
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Recruiting
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RecruitingObservational study
Universal Rare Gene Study: A Registry and Natural History Study of Retinal Dystrophies Associated With Rare Disease-Causing Genetic Variants
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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.

Michael Beyeler, PhD principal investigator

University of California, Santa Barbara

3 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A study testing Argus II in people with Retinitis Pigmentosa, run by University of California, Santa Barbara at 3 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 7 inclusion and 4 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 1 Jan 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 3 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 1 Jan 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?

Number of Phosphenes Perceived (time frame: during single-session testing). 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 NCT05285618, which also lists 2 linked publications.

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 1 Jan 2025.