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The Argus II retinal prosthesis (Second Sight Medical Products, Sylmar, CA, USA) is an electronic epiretinal implant designed for use in patients with end-stage retinitis pigmentosa, as well as for other outer retinal degenerative conditions, such as choroideremia, Leber’s congenital amaurosis, Bardet-Biedl syndrome, Usher syndrome and rod–cone disease.1 This device was tested in a clinical trial of 30 subjects in the USA and in Europe to measure the rate of serious adverse events (SAEs) and to assess its effects on functional vision and visual acuity.2–4 Subjects performed better on visual tasks with the device turned on and retained these improvements at 5 years postsurgery.4 Additionally, an acceptable safety profile enabled approval of the device for consumer use by the European regulatory authorities in 2011 (Conformité Européenne (CE) mark) and by the US Food and Drug Administration (FDA) in 2013 (FDA approval).
The implant is composed of an extraocular component, namely, an electronics case and implant coil, as well as an intraocular component involving a 60-electrode array that is tacked over the macula (figure 1). The extraocular and intraocular components are connected by a trans-scleral silicone-coated polyamide electrode cable, and the implantation procedure involves a 5.2 mm pars plana sclerotomy incision to insert the electrode array and the electrode cable into the eye. The sclerotomy is then sutured around the cable and covered by an allograft or autograft material.5
As with any system having both intraocular and extraocular components, the trans-scleral electrode cable that traverses the sclerotomy permanently is a high-risk feature of the device, as leakage through the pars plana incision can result in chronic hypotony. The percentages of clinical trial subjects who experienced hypotony were 10.0% at …
Contributors Planning the research and conception or design of the work: SR. Data collection: SR, POB, SAS, RGD, MND, JFK, AR, AY, KTJ, DZ, JTH, SRM, DK, PES, LDC, PW, AJA, LCODK, ACH, BK, PH, LV, RIj, DG, JFA, NZG, PW, EO, JIL, FAR, SSH, FM, UP, RJG, SJ, DB, LC and MSH. Data analysis and interpretation: LCODK, ACH, BK, PH, LV, RIj, DG, JFA, NZG, PW, EO, JIL, FAR, SSH, FM, RJG and SJ. Drafting the article: SR, LC, DB, MSH, SAS, RGD, MND, JFK, AR, AY, KTJ, DZ, JTH, SRM, DK, PES, LDC, PW and AJA. Critical revision and final approval: SR, LC, DB and MSH.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests RGD, SRM, PES, AJA, ACH, PH, LV, EO and SSH are consultants for Second Sight. The authors report no other competing or financial interests in the work.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.
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