Argus II retinal prosthesis implantation with scleral flap and autogenous temporalis fascia as alternative patch graft material: a 4-year follow-up

Abstract

IntroductionThe Argus II retinal prosthesis is composed of an epiretinal electrode array positioned over the macula and connected to an extrascleral electronics case via a silicone cable, running through a sclerotomy. During implantation, the manufacturer recommends to cover the sclerotomy site with a patch of processed human pericardium to prevent postoperative hypotony and conjunctival erosion by the underlying electronics case. Due to biomedical regulations prohibiting the use of this material in France, we developed an alternative technique combining a scleral flap protecting the sclerotomy and an autogenous graft of superior temporalis fascia overlying the electronics case.MethodsThe purpose of this study is to describe the 4-year outcomes of this modified procedure in three subjects who underwent Argus II Retinal Prosthesis System implantation. Clinical data consisting of intraocular pressure measurements and tolerance in terms of conjunctival erosion or inflammation were retrospectively assessed over a 4-year postoperative follow-up.ResultsNone of the three patients implanted with the modified technique developed ocular hypotony over 4 years. A normal, transient conjunctival inflammation occurred during the first postoperative month but conjunctival erosion was not observed in any of the three patients over 4 years. Four years after implantation, the autogenous temporalis fascia graft remained well tolerated and the retinal prosthesis was functional in all three patients.ConclusionThe combination of an autograft of superficial temporalis fascia and a scleral flap efficiently prevented leakage through the sclerotomy site, ocular hypotony, and conjunctival erosion by the extrascleral electronics case. This modified technique is suitable for the implantation of existing and forthcoming retinal prostheses. Superficial temporalis fascia may also be used as alternative to commercial tectonic tissues for scleral wound repair in clinical settings where they are not available.

Assessment of the Electronic Retinal Implant Alpha AMS in Restoring Vision to Blind Patients with End-Stage Retinitis Pigmentosa

“…The likely cause of conjunctival retraction and foil exposure was tension at the limbal wound due to anterior prominence of the scleral patch. Although alternatives to scleral allograft exist (e.g., temporalis fascia autograft 21 ), the risk of wound dehiscence was ameliorated in subsequent cases by construction of a 2-mm corneoscleral pocket to receive the anterior most edge of the scleral graft, thus smoothing the conjunctival profile and lessening tissue tension in the vicinity of the limbal conjunctival wound. It is likely that surgical techniques will improve with further refinements as we gain more experience with retinal implant surgery.…”

Argus II retinal prosthesis system: a review of patient selection criteria, surgical considerations, and post-operative outcomes

“…The use of processed pericardium Tutoplast (IOP Ophthalmics Inc., Costa Mesa, CA, USA) or temporalis fascia autograft 32 or a corneal patch graft over the electronics case and coil is critical to decreasing the risk of device exposure. The use of a scleral flap along with temporalis fascia autograft prevented any cases of hypotony and conjunctival erosion in one series.…”