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Artificial Vision Clinical Trials

Epiretinal Devices

Following on from the safety and efficacy observed in 6 patients in whom the Argus I device was implanted, the Argus II Retinal Prosthesis System was developed and investigated in a clinical study of 30 patients with end-stage RP and remaining visual acuity of bare light perception or worse. Investigators monitored participants for adverse events related to the device or to the implant surgery and regularly assessed their vision for at least two years after receiving the implant. Some participants have used the system for up to 6 years and continue to use it.

Results from the clinical study show that many participants were able to perform basic activities of daily living better with the Argus II Retinal Prosthesis System than without it. Some of the activities tested included locating and touching a square on a white field; detecting the direction of motion; recognizing large letters, words, or sentences; detecting street curbs; walking on a sidewalk without stepping off; and matching black, grey and white socks.

The Argus II implant offers a visual field of 20° and consists of 60 electrodes. It received marketing approval in Europe (CE Mark) in Feb 2011, and US FDA Approval in Feb 2013. In the UK, the Argus II is approved for use in adults, age 25 years or older; suffering from severe to profound blindness due to outer retinal degeneration (such as Retinitis Pigmentosa).

Further information is available at:
clinicaltrials.gov/ct/show/NCT00407602?order=1
medgadget.com/archives/2007/01/second_sight_me.html

Subretinal Devices

A group in Germany led by Professor Zrenner has been doing research on a subretinal implant (placed between the RPE and overlying retinal layers Figure 2 About RP Section) for a number of years. A preliminary study has been completed (2008). The implant contains 1500 microelectrodes. It is 3x3 mm in size and 70 microns thick producing a field of 12 degrees, enough for mobility and recognition of objects. The implant is being developed by Retina Implant AG.
Figure 31 - Retinal Implant in a person with RP

Figure 31 - Retinal Implant in a person with RP

Figure 32 - A second person with RP with a retinal implant

Figure 32 - A second person with RP with a retinal implant

The preliminary study of 7 people with RP was designed to last 4 weeks although in one patient the retinal device remains implanted after 18 months. Six of the seven people with RP have had light perception restored. Two patients could discern simple patterns. Three patients could locate a bright object such as a light coloured plate. One of the advantages of this device compared to the Argus II is that there is no external camera or power source – everything is located within the eye. A larger multi-centre study (including King's College Hospital and the John Radcliffe Hospital in the UK) is on-going and actively currently recruiting (2013). A total of patients will receive implants in this trial.

Further information is available at:
clinicaltrials.gov/ct2/show/NCT01024803?term=retina+implant+ag&rank=2


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