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R. N. Agrawal, R. Freda, B. Mech, J. S. Little, R. J. Greenberg, M. S. Humayun; Outcomes of Surgical Techniques and Chronic Implantation of the SSMP Argus II Intraocular Retinal Prosthesis Implant. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4050. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To develop the surgical implantation procedure and evaluate long term outcomes of implantation of the SSMP Argus II Intraocular Retinal Prosthesis (IRP)
All procedures conformed to ARVO resolution on use of animals & were approved by USC-IACUC. Mechanical models of Argus II (Second Sight Medical Products, Sylmar, CA) were implanted in the right eye of 33 healthy canines. The device is externally made up of a package & a coil integrated on a silicone band. Following a routine 20G vitrectomy, a polymer cable & array enter the eye through an enlarged sclerotomy & is fixed to the macula with a retinal tack. Diagnostic procedures included baseline & post-operative eye exams, intraocular pressure (IOP), color fundus photography (CFA), fluorescein angiography (FA) & optical coherence tomography (OCT). A 6-month follow-up period was planned, with early euthanasia for any adverse events like retinal detachment or infection.
CF & FA did not show any significant damage on follow-up, while OCT depicted array’s proximity to the retina. Vitreous hemorrhage and retinal detachment were found to be the most common adverse events. Canine eyes are more vascular and hence frequently develop vitreous hemorrhage at conclusion of surgery. This usually resolved in early post-operative period. Most of the retinal detachments occurred in the early phase of device development. There was one case of Staph. intermedius endophthalmitis; this organism is commonly found on the surface of canine body and possibly found accidental entry into the eye during the procedure. An organized, thin capsule was found around the package and the coil on gross dissection, similar to a scleral buckle, with mild indentation under the coil, package and band.
Surgical procedure for implantation of the Argus II was found to be feasible and safe during the study period. FDA has given clearance for a multicentric clinical trial that is currently in progress.
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