NCT05285618

The Perceptual Experience of Argus II Users

Predicting the Perceptual Experience of Argus II Retinal Prosthesis System Users

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 6 (actual)
• Sponsor: University of California, Santa Barbara · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Accepted

Summary

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.

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

Interventions

Type	Name	Description
DEVICE	Argus II	Participants used the Argus II retinal prosthesis system in both experiments to perform visual perception tasks.

Timeline

• Start date: 2022-01-11
• Primary completion: 2023-08-31
• Completion: 2023-08-31
• First posted: 2022-03-17
• Last updated: 2025-01-01
• Results posted: 2025-01-01

Locations

3 sites across 1 country: United States

Regulatory

• FDA-regulated device study