Second Sight Medical Products’ Argus II retinal prosthesis system has demonstrated improvements in blind people suffering from degenerative diseases such as retinitis pigmentosa.
Argus II is an implantable device that works by converting video images captured from a miniature camera, housed in the patient’s glasses, into a series of small electrical pulses that are transmitted wirelessly to an array of electrodes on the surface of the retina.
The single-arm controlled prospective multicentre clinical trial of Argus II retinal prosthesis system included a total of 30 patients who were implanted with the prosthesis and followed up for a minimum of six months and up to 2.7 years.
In the study three types of visual acuity tests were performed using computer monitors – square localisation, direction of motion and grating visual acuity – and two types of real-world orientation and mobility (O&M) tests were performed – a door test and a line test.
The trial showed that 96% of subjects improved in object localisation, 57% of subjects improved in motion discrimination and 23% of subjects improved in the discrimination of oriented gratings.
Subjects implanted with Argus II system also showed considerable improvements in the O&M tasks and the safety profile of Argus II was found to be comparable to other ophthalmic devices and procedures.
Lead author of the study Mark Humayun said: "The Argus II retinal prosthesis is now approved as a medical implant in Europe and the results to date are very encouraging for patients with end-stage outer retinal degenerations such as retinitis pigmentosa."
He added: "The results from the trial demonstrated long-term reliability and showed that the previously blind subjects performed better at visual tasks with the Argus II system such as object localisation and motion discrimination."
Second Sight Medical Products aims to develop, manufacture and market implantable visual prosthetics to allow blind individuals achieve greater independence.
Image: Fundus of patient with retinitis pigmentosa, bone spicule-shaped pigment deposits are present in the mid periphery along with retinal atrophy, while the macula is preserved although with a peripheral ring of depigmentation. Photo: Christian Hamel.