Surgical Implantation of 1.5 Generation Retinal Implant in Minipig Eyes

Abstract

 

Purpose:

 

This work is related to the efforts of the Boston Retinal Implant Project to develop a sub-retinal prosthesis to restore vision to the blind. This presentation summarizes the surgical results of implantation of 1.5 generation retinal implant in minipig eyes.

 

Methods:

 

2 active and 10 inactive 1.5 generation retinal implants were implanted into 12 minipig eyes via an ab externo method to study in vivo electrical function and biocompatibility. Our active implants contain a circuitry module, secondary power and data receiving coils, and 15 µm-thick, 4mm wide polyimide-based flexible electrode arrays. 4/10(4 out of 10) inactive implants do not have arrays. To prevent excessive bleeding, "controlled" systemic hypotension was introduced during insertion. A local retinal detachment was created after vitrectomy. The coils were sutured around the cornea and the titanium cases were sutured onto sclera nasally. Electrode arrays were placed into subretinal space temporally with an ab externo method. Conjunctiva was closed over the implant.

 

Results:

 

7/8 electrode arrays were successfully implanted into subretinal space. 1 electrode array went into vitreous. Retinal incarceration happened in 1 surgery. No other surgical complications were observed. 3 pigs died of anesthesia complications after surgery. 7/11 eyes had exposure of the coils (5 eyes), the case (1 eye) and between the coil and the case (1 eye). 6/7 exposures happened nasally. Two active devices were functional for more than 2 months in vivo.

 

Conclusions:

 

Our 1.5 generation retinal implant can be safely implanted in Yucatan minipig eyes with our ab externo methods. More experiments will be done to improve the long term biocompatibility of our device.  

 

Keywords: vitreoretinal surgery • retinal detachment • conjunctiva