Operation and Performance of Eye-conformable Retinal Prosthesis using Liquid Crystal Polymer

Abstract

 

Purpose

 

A miniaturized and eye-surface conformable novel retinal prosthesis using monolithic encapsulation and deformation of biocompatible Liquid Crystal Polymer (LCP) was developed, and its in vivo functionality and long term reliability was assessed.

 

Methods

 

A miniaturized and eye-conformable retinal implant was fabricated through monolithic integration of all the electronic components on a multilayered LCP substrate. Electronics include 16-channel electrode array, multilayered planar coil and 16-channel current stimulator IC (AMS HV CMOS 0.35um). The LCP substrate was spherically deformed to fit the curvature of the eyeball. Stimulation parameters were controlled using a touchscreen-based external unit which can generate power and pulse-width-modulated (PWM) data for the wireless transmission via an inductive link at 2.5MHz. The device was implanted into the rabbit eye to evaluate its functionality and long-term stability by attaching the package on the superotemporal quadrant of the scleral surface under the Tenon's capsule and inserting the electrode array into the suprachoroidal space via superonasal incision.

 

Results

 

The developed LCP-based monolithic retinal implant with circular package of 14mm in diameter and 1.5 mm in the maximum thickness was fabricated. Stimulation patterns and waveforms could be adjusted through the graphic user interface of an external unit and the transmitter coil attached on the skin up to coil distance of 17 mm in vivo. The device could be successfully implanted into the rabbit eye and has been stably implanted for more than 4 months without showing any adverse sign.

 

Conclusions

 

The exterior unit as well as the implantable unit performed as designed. Accelerated soak tests and in vivo animal test to verify their reliability and stability for an extended period of time are ongoing at this moment.

 

 

Keywords: 688 retina • 741 transplantation