Sequence of visual cortex stimulation affects phosphene brightness in blind subjects.

Background: Visual cortical prostheses (VCP) could potentially benefit a majority of the blind population. Feasibility testing of these VCP opens new avenues to characterize stimulation of visual cortex in blind subjects.

Objective/hypothesis: To determine if sequential stimulation of visual cortex produces a perception bias in phosphene brightness.

Multi-electrode stimulation evokes consistent spatial patterns of phosphenes and improves phosphene mapping in blind subjects.

Background: Visual cortical prostheses (VCPs) have the potential to restore visual function to patients with acquired blindness. Successful implementation of VCPs requires the ability to reliably map the location of the phosphene produced by stimulation of each implanted electrode.

Objective: To evaluate the efficacy of different approaches to phosphene mapping and propose simple improvements to mapping strategy.

Eye movements and the perceived location of phosphenes generated by intracranial primary visual cortex stimulation in the blind.

Background: Restoring sight for the blind using electrical stimulation of the visual pathways is feasible but demands an understanding of the spatial mapping of the visual world at the site of targeted stimulation, whether in the retina, thalamus, or cortex. While a visual cortex stimulator can bypass the eye and create visual percepts, there is an inherent dissociation between this stimulation and eye movements. It is unknown whether and how robustly the brain maintains the oculomotor circuitry in patients with bare- or no-light perception.

Electronic retinal prosthesis for severe loss of vision in geographic atrophy in age-related macular degeneration: First-in-human use.

Background: To date there are yet no available approved therapies for Geographic Atrophy (GA) secondary to age-related macular degeneration (AMD).

Methods: Single site, non-randomized safety and efficacy study presenting the preliminary results in a cohort of five late stage AMD (GA) patients successfully implanted with the Argus II Retinal Prosthesis System (Second Sight Medical Products Inc., Sylmar, CA, USA).

Improved performance and safety from Argus II retinal prosthesis post-approval study in France.

Purpose: To evaluate the post-approval long-term outcomes of the Argus II Retinal Prosthesis, with a specific focus on its functional visual benefit in patients' daily activities.

Methods: Eighteen patients with bare light perception due to end-stage retinitis pigmentosa were included in a French prospective, multicentre, single-arm study and followed for 2 years. Visual benefit in patients' daily activities was monitored through the use of the Functional Low-vision Observer Rated Assessment (FLORA), and the final score at 2 years was the primary effectiveness outcome.

Improved localisation and discrimination of heat emitting household objects with the artificial vision therapy system by integration with thermal sensor.

Aim: To demonstrate the potential clinically meaningful benefits of a thermal camera integrated with the Argus II, an artificial vision therapy system, for assisting Argus II users in localising and discriminating heat-emitting objects.

Methods: Seven blind patients implanted with Argus II retinal prosthesis participated in the study. Two tasks were investigated: (1) localising up to three heat-emitting objects by indicating the location of the objects and (2) discriminating a specific heated object out of three presented on a table.

Retina-electrode interface properties and vision restoration by two generations of retinal prostheses in one patient-one in each eye.

Objective: The Argus I implant is a first-generation epiretinal prosthesis approved for an investigational clinical trial in the U.S. Its successor, the Argus II implant, has a higher electrode density for increased spatial resolution and covers a larger retinal area to accommodate a wider visual angle.

Phosphene perceptions and safety of chronic visual cortex stimulation in a blind subject.

Stimulation of primary visual cortices has the potential to restore some degree of vision to blind individuals. Developing safe and reliable visual cortical prostheses requires assessment of the long-term stability, feasibility, and safety of generating stimulation-evoked perceptions.A NeuroPace responsive neurostimulation system was implanted in a blind individual with an 8-year history of bare light perception, and stimulation-evoked phosphenes were evaluated over 19 months (41 test sessions).

One-Year Safety and Performance Assessment of the Argus II Retinal Prosthesis: A Postapproval Study.

Importance: The Argus II Retinal Prosthesis System is indicated for patients with vision loss due to severe to profound outer retinal degeneration, a group with few treatment options.

Objectives: To collect postapproval safety and visual function data for the Argus II.

Design, Setting, And Participants: Multicenter, postapproval clinical trial conducted at 9 sites in Germany and Italy.

Eye movements as a marker for visual prosthesis spatial mapping - A feasibility study using a blind patient implanted with the Argus II retinal prosthesis.

Spatial mapping, the location in space of a perceived location due to an implanted electrode's electrical stimulation is important in the design of visual prostheses. Generally, a visual prosthesis system consists of an implanted electrode array, an external camera that acquires the image, and a transmitter that sends the information to the implanted electrodes. In cortical visual implant, the layout of the implanted array in most cases does not match the retinotopic map and it is necessary to find the location of the percept of each electrode in world coordinates.

Retinotopic to Spatiotopic Mapping in Blind Patients Implanted With the Argus II Retinal Prosthesis.

Purpose: To quantify the precision of mapping from retinotopic (retina-centered) to spatiotopic (world-centered) coordinates in blind humans implanted with a retinal prosthesis device. Additionally, to demonstrate that an eye tracker can be calibrated on sightless patients based on the percept from a visual implant.

Methods: We directly activated epiretinal electrodes to create retinotopic stimuli and recorded the location of the percept at world-based coordinates.

Improvements in vision-related quality of life in blind patients implanted with the Argus II Epiretinal Prosthesis.

Background: The purpose of this analysis is to report the change in quality of life (QoL) after treatment with the Argus II Epiretinal Prosthesis in patients with end-stage retinitis pigmentosa.

Methods: The Vision and Quality of Life Index (VisQoL) was used to assess changes in QoL dimensions and overall utility score in a prospective 30-patient single-arm clinical study. VisQoL is a multi-attribute instrument consisting of six dimensions (injury, life, roles, assistance, activity and friendship) that may be affected by visual impairment.

Performance of real-world functional vision tasks by blind subjects improves after implantation with the Argus® II retinal prosthesis system.

Background: The main objective of this study was to test Argus II subjects on three real-world functional vision tasks.

Design: The study was designed to be randomized and prospective. Testing was conducted in a hospital/research laboratory setting at the various participating centres.

Five-Year Safety and Performance Results from the Argus II Retinal Prosthesis System Clinical Trial.

Purpose: The Argus II Retinal Prosthesis System (Second Sight Medical Products, Inc, Sylmar, CA) was developed to restore some vision to patients blind as a result of retinitis pigmentosa (RP) or outer retinal degeneration. A clinical trial was initiated in 2006 to study the long-term safety and efficacy of the Argus II System in patients with bare or no light perception resulting from end-stage RP.

Design: Prospective, multicenter, single-arm clinical trial.

Worldwide Argus II implantation: recommendations to optimize patient outcomes.

Background: A position paper based on the collective experiences of Argus II Retinal Prosthesis System investigators to review strategies to optimize outcomes in patients with retinitis pigmentosa undergoing retinal prosthesis implantation.

Methods: Retinal surgeons, device programmers, and rehabilitation specialists from Europe, Canada, Middle East, and the United States were convened to the first international Argus II Investigator Meeting held in Ann Arbor, MI in March 2015. The recommendations from the collective experiences were collected.

An analysis of observer-rated functional vision in patients implanted with the Argus II Retinal Prosthesis System at three years.

Objective: The purpose of this analysis was to compare observer-rated tasks in patients implanted with the Argus II Retinal Prosthesis System, when the device is ON versus OFF.

Methods: The Functional Low-Vision Observer Rated Assessment (FLORA) instrument was administered to 26 blind patients implanted with the Argus II Retinal Prosthesis System at a mean follow-up of 36 months. FLORA is a multi-component instrument that consists in part of observer-rated assessment of 35 tasks completed with the device ON versus OFF.

OPTOMAP WIDEFIELD IMAGING OF THE ARGUS II RETINAL PROSTHESIS IN PATIENTS WITH RETINITIS PIGMENTOSA.

Purpose: To explore the utility of using ultra-widefield imaging to visualize the Argus II implant in the eyes of three patients with retinitis pigmentosa.

Methods: Case series of three patients with retinitis pigmentosa who were implanted with the Argus II Retinal Prosthesis System; two of whom were enrolled in the Argus II clinical trial and one received the implant after the commercial release of the device. Optomap widefield fundus autofluorescence and color images of both eyes were taken in all three patients by an experienced technician using the Optos 200Tx imaging system.

Ten-Year Follow-up of a Blind Patient Chronically Implanted with Epiretinal Prosthesis Argus I.

Purpose: The Argus I implant is the first-generation epiretinal prosthesis approved for an investigational clinical trial by the United States Food and Drug Administration. Herein we report testing results obtained from a 10-year follow-up to study the physiologic effects of the bioelectronic visual implant after prolonged chronic electrical stimulation.

Design: Case report.

Long-Term Results from an Epiretinal Prosthesis to Restore Sight to the Blind.

Purpose: Retinitis pigmentosa (RP) is a group of inherited retinal degenerations leading to blindness due to photoreceptor loss. Retinitis pigmentosa is a rare disease, affecting only approximately 100 000 people in the United States. There is no cure and no approved medical therapy to slow or reverse RP.

FLORA™: Phase I development of a functional vision assessment for prosthetic vision users.

Background: Research groups and funding agencies need a functional assessment suitable for an ultra-low vision population to evaluate the impact of new vision-restoration treatments. The purpose of this study was to develop a pilot assessment to capture the functional visual ability and well-being of subjects whose vision has been partially restored with the Argus II Retinal Prosthesis System.

Methods: The Functional Low-Vision Observer Rated Assessment (FLORA) pilot assessment involved a self-report section, a list of functional visual tasks for observation of performance and a case narrative summary.

The Detection of Motion by Blind Subjects With the Epiretinal 60-Electrode (Argus II) Retinal Prosthesis.

Objective: To investigate the ability of 28 blind subjects implanted with a 60-electrode Argus II (Second Sight Medical Products Inc) retinal prosthesis system to detect the direction of a moving object.

Methods: Blind subjects (bare light perception or worse in both eyes) with retinitis pigmentosa were implanted with the Argus II prosthesis as part of a phase 1/2 feasibility study at multiple clinical sites worldwide. The experiment measured their ability to detect the direction of motion of a high-contrast moving bar on a flatscreen monitor in 3 conditions: with the prosthesis system on and a 1-to-1 mapping of spatial information, with the system off, and with the system on but with randomly scrambled spatial information.

The Argus II epiretinal prosthesis system allows letter and word reading and long-term function in patients with profound vision loss.

Background: Retinal prosthesis systems (RPS) are a novel treatment for profound vision loss in outer retinal dystrophies. Ideal prostheses would offer stable, long-term retinal stimulation and reproducible spatial resolution in a portable form appropriate for daily life.

Methods: We report a prospective, internally controlled, multicentre trial of the Argus II system.

Reading visual braille with a retinal prosthesis.

Retinal prostheses, which restore partial vision to patients blinded by outer retinal degeneration, are currently in clinical trial. The Argus II retinal prosthesis system was recently awarded CE approval for commercial use in Europe. While retinal prosthesis users have achieved remarkable visual improvement to the point of reading letters and short sentences, the reading process is still fairly cumbersome.