Modified 23-Gauge Microincisional Vitrectomy Surgery (MIVS ) Technique For The Implant Of The Argus II Retinal Prostesis

Abstract

Purpose: : To describe our modified surgical technique for the implant of the Argus II epiretinal prosthesis (Second Sight Medical Products,Sylmar, California, USA) aimed at partially restoring vision to people blinded by retinitis pigmentosa (RP).

Methods: : Argus II system consists of a surgically implanted 60-electrode stimulating microelectrode array consisting of 200 μm diameter disc electrode, an inductive coil link used to transmit power and data to the internal portion of the implant, an external belt-worn video processing unit and a miniature camera mounted on a pair of glasses, and had been implanted with 20 gauge (G) pars plana vitrectomy (PPV). We used 23 G high speed MIVS (Alcon Constellation), instead of standard 20 G ppv. To maintain an adequate intraocular pressure control, Alcon 23 G valved trocars (Valved Entry System) were applied at 7 o’ clock position for the infusion cannula and at 3 and 9 o’clock by using a straight insertion modality in order to allow an easy access to all the vitreous chamber and to facilitate the tackling manouvre. A 25 G chandelier light was placed at six o’clock to provide illumination, setting free the surgeon’s second hand. At the time of the insertion of the retinal tack, we removed the nasal trocar and enlarged the sclerotomy with a 19 G MVR blade. After the tack was placed we applied a 20 G to 23 G calliper reducer to complete the vitrectomy.

Results: : the surgery was performed in 3 hour and 45 minutes, without any complication.

Conclusions: : Our technique was safe and could be advantageous. The use of a high speed vitrectomy cutter ensured a safe vitreous aspiration with less retinal tractions. Valved cannulas reduced IOP spikes during surgery, decreasing vitreous prolapse through the sclerotomies and reducing consumption of BSS. As a consequence fluid turbulence in the vitreous chamber was lower, thus allowing a good stability of the implant during the tack positioning, therefore making this challenging manoeuvre easier.

Keywords: vitreoretinal surgery • degenerations/dystrophies • retinal degenerations: hereditary