Retinal prostheses and vision restoration

Also known as Bionic eye, Retinal implant, Visual prosthesis, Argus II, PRIMA subretinal implant

Retinal prostheses are implants that use electrodes or light-sensitive chips to stimulate the remaining retina in people who have lost their light-sensing cells. The Argus II was approved by the FDA in 2013 for advanced retinitis pigmentosa, and its production was suspended in 2019, while the PRIMA implant improved central vision for most participants assessed in a 2025 trial in geographic atrophy.

Pilot and early commercialDemonstratedReviewed 21 Oct 2026
AI illustration · Illustrative scene, not a photograph of the specific device or experiment.

In plain language

Some eye diseases destroy the light-sensing cells at the back of the eye while leaving the nerve cells behind them partly working. A retinal prosthesis tries to use those surviving cells. A camera or a light pattern is turned into electrical or light-driven signals, and an implant stimulates the retina so that the brain receives a rough picture.

The results so far are modest. The first approved device, the Argus II, was approved for adults with severe retinitis pigmentosa, and the FDA said it may help users detect light and dark and identify the location or movement of objects, but that it will not restore vision. A newer subretinal chip, PRIMA, improved central vision for many people in a 2025 trial of people with an advanced form of age-related macular degeneration. The sources reviewed do not confirm regulatory approval for PRIMA.

Technical explanation

The Argus II is an implanted electrode array. It was approved in Europe in 2011 and by the FDA in February 2013 under a humanitarian use device pathway for adults aged 25 or older with severe to profound retinitis pigmentosa (RP) who have only light perception or no light perception in both eyes. In the 30-subject interim trial (Humayun and colleagues, 2012), performance on object localisation was better with the system on in 96% of subjects, motion discrimination was better in 57%, and the best recorded visual acuity was 20/1260. The most common serious adverse event was conjunctival erosion or dehiscence over the external part of the implant.

Subretinal implants place the stimulating electrodes or photodiodes behind the retina, where they can replace the function of lost photoreceptors. Stingl and colleagues (2013) reported a wirelessly powered subretinal implant in nine patients with RP. Light perception was detected in eight of nine patients, light localisation in seven, and motion detection in five. Grating acuity was measured in six patients, and Landolt C acuity was reached by two.

PRIMA is a subretinal photovoltaic implant designed for geographic atrophy, an advanced form of age-related macular degeneration. The PRIMA system combines the subretinal implant with glasses that project near-infrared light onto it. In an open-label, single-group, baseline-controlled study of 38 participants (Holz and colleagues, 2025), 32 were assessed at 12 months and 26 of them (81%) had a clinically meaningful improvement in visual acuity from baseline, defined as at least 0.2 logMAR. Multiple imputation for the six participants not assessed estimated that 80% of all 38 would have improved. Twenty-six serious adverse events occurred in 19 participants, 21 of them within two months of surgery. The authors concluded that the PRIMA system restored central vision and led to a significant improvement in visual acuity from baseline to month 12.

What the evidence says

Each statement is typed by the strength of its evidence and linked to the source that supports it.

Demonstrated Shown in a published experiment, test or shipping product.

The FDA approved the Argus II in February 2013 under a humanitarian use device pathway, for adults aged 25 or older with severe to profound retinitis pigmentosa and only light perception or no light perception in both eyes.

Sources: [1], [5]

The FDA stated that the Argus II may help users detect light and dark and identify the location or movement of objects, but that it will not restore vision.

Sources: [1]

In the 30-subject Argus II interim trial, performance on object localisation was better with the system on in 96% of subjects, and the best recorded visual acuity was 20/1260.

Sources: [2] · Abstract

In the Argus II interim trial, the most common serious adverse event was conjunctival erosion or dehiscence over the external part of the implant, and one device required explantation.

Sources: [2] · Abstract

In nine patients with retinitis pigmentosa who received a wirelessly powered subretinal implant, light perception was detected in eight and motion detection in five.

Sources: [3] · Abstract

In an open-label, single-group, baseline-controlled study of 38 people with geographic atrophy, 26 of the 32 assessed at 12 months (81%) had a clinically meaningful improvement in visual acuity from baseline.

Sources: [4] · Results

The PRIMA trial recorded 26 serious adverse events in 19 participants, 21 of which occurred within two months after surgery.

Sources: [4] · Results

Second Sight temporarily suspended production of the Argus II in May 2019 to accelerate development of its Orion brain implant.

Sources: [5] · medium confidence

Multiple imputation for the six PRIMA participants not assessed at 12 months estimated that 80% of all 38 participants would have improved by at least 0.2 logMAR (95% CI 66 to 94).

Sources: [4] · Abstract

Of the six PRIMA participants not assessed at 12 months, three had died, one had withdrawn and two were unavailable for testing.

Sources: [4] · Abstract

Of the 26 serious adverse events in the PRIMA trial, 21 occurred within two months of surgery, and 20 of those 21 resolved within two months of onset.

Sources: [4] · Abstract

The PRIMA system combines a subretinal photovoltaic implant with glasses that project near-infrared light onto the implant.

Sources: [4] · Abstract

Limitations and open problems

  • Restored vision is limited. The FDA said the Argus II will not restore vision, and the best acuity in the 2012 interim trial was 20/1260 (Humayun and colleagues, 2012).
  • The trials are small. The Argus II interim trial enrolled 30 subjects, and the PRIMA trial was open-label and single-group with 38 participants (Humayun and colleagues, 2012; Holz and colleagues, 2025).
  • Serious complications occur. In the Argus II interim trial, conjunctival erosion was the most common serious adverse event and one device was explanted. PRIMA reported 26 serious adverse events in 19 participants (Humayun and colleagues, 2012; Holz and colleagues, 2025).
  • Missing data affect the all-participant estimate. Six PRIMA participants were not assessed at 12 months: three had died, one had withdrawn and two were unavailable for testing. The 80% estimate depends on multiple imputation and its assumptions (Holz and colleagues, 2025).
  • Commercial support is fragile. Second Sight temporarily suspended Argus II production in May 2019, and the AAO EyeNet article does not say whether production resumed (AAO EyeNet, 2019).
  • The PRIMA results concern central vision in geographic atrophy, not retinitis pigmentosa, and the sources reviewed do not confirm a regulatory approval for PRIMA.
  • Acuity gains are not everyday function. The primary endpoint is a gain in visual acuity, and the abstract does not report reading speed, face recognition or mobility outcomes (Holz and colleagues, 2025).

Possible future uses

Speculative

Ideas, not predictions. None of these has been demonstrated.

  • Implants with more electrodes or pixels that could produce finer images, which current trial results do not yet show.
  • Pairing implants with image-processing software that helps users recognise faces or read large text.
  • Use in other inherited retinal diseases beyond retinitis pigmentosa and geographic atrophy.

Timeline

  1. 2011The Argus II is approved in Europe, as reported by the AAO EyeNet. Sources: [5]
  2. Apr 2012Humayun and colleagues publish interim results of the 30-subject international Argus II trial in Ophthalmology. Sources: [2]
  3. Feb 2013The FDA approves the Argus II for adults with advanced retinitis pigmentosa under a humanitarian use device pathway. Sources: [1]
  4. Apr 2013Stingl and colleagues report a wirelessly powered subretinal implant in nine patients with retinitis pigmentosa. Sources: [3]
  5. May 2019Second Sight temporarily suspends production of the Argus II to focus on the Orion brain implant. Sources: [5]
  6. 20 Oct 2025The New England Journal of Medicine publishes the PRIMA trial, reporting visual acuity improvement in 26 of 32 participants assessed at 12 months. Sources: [4]

Futures this could help bring about

AI illustration
How far away?

Restoring sight to blind people

Pilots · 4 of 8 steps done

Related breakthroughs

Glossary

Retinitis pigmentosa
An inherited condition in which the light-sensing photoreceptor cells of the retina gradually degenerate.
Geographic atrophy
An advanced form of age-related macular degeneration in which areas of the retina's light-sensing layer are lost.
Humanitarian use device
An FDA pathway for devices intended to treat or diagnose fewer than 4,000 people in the United States each year. Sponsors must show reasonable assurance of safety and a probable benefit that outweighs risk.
Visual acuity
A measure of how fine a detail a person can see. A value of 20/1260 means the person must be 20 feet away to see what a person with normal vision sees at 1260 feet.
Subretinal implant
A device placed under the retina, behind its light-sensing layer.
Photovoltaic pixel
A pixel that converts incoming light into electrical current.

Sources

  1. news
    FDA approves first retinal implant for adults with rare genetic eye disease
    ScienceDaily (reprint of the FDA announcement), Feb 2013. Accessed 21 Oct 2026.
  2. peer reviewed paper
    Interim results from the international trial of Second Sight's visual prosthesis
    Mark S. Humayun. Ophthalmology, Apr 2012. DOI: 10.1016/j.ophtha.2011.09.028. Accessed 21 Oct 2026.
  3. peer reviewed paper
    Artificial vision with wirelessly powered subretinal electronic implant alpha-IMS
    Katarina Stingl. Proceedings of the Royal Society B: Biological Sciences, 22 Apr 2013. DOI: 10.1098/rspb.2013.0077. Accessed 21 Oct 2026.
  4. peer reviewed paper
    Subretinal Photovoltaic Implant to Restore Vision in Geographic Atrophy Due to AMD
    Frank G. Holz. New England Journal of Medicine, 20 Oct 2025. DOI: 10.1056/NEJMoa2501396. Accessed 21 Oct 2026.
  5. other
    Retinal Implants for RP: An Update on Argus II and Others
    Rohan Bajaj, Gislin Dagnelie, James T. Handa et al.. American Academy of Ophthalmology (EyeNet), 2 Dec 2019. Accessed 21 Oct 2026.

Revision history

6 changes since this profile was created.

Changes on 21 Oct 2026
Published on owner instruction (content loop iteration 3)840d796
Sources and claims re-checked against originals2870320
Updated with Codex research: added PRIMA non-assessment and imputation detail, serious adverse event resolution counts, the PRIMA system description and the NEJM print date; the 2024 four-year follow-up and ClinicalTrials.gov records were not added because the primary texts could not be opened.0ce9ad8
Published on owner instruction via content loop; AI-researched, QA-checked and link-checkeddb92240
Sources and claims re-checked against originalsfbb434c
Initial profile drafted from primary sources7e66249