Towards an Optogenetic Retinal Prosthesis

Abstract

 

Purpose:

 

Research by the World Health Organisation (WHO) in 2002 determined that an estimated 37 million people worldwide were blind. One leading cause of blindness in the developed world is retinitis pigmentosa (RP) for which there is no effective rehabilitation treatment today. Electronic prosthesis have enabled blind patients to perceive phosphenes with limited resolution. In this paper we describe the development of an optogenetic retinal prosthesis based on genetically re-engineering retinal ganglion cells to express the light sensitive ion channel ChannelRhodopsin-2 (ChR2).

 

Methods:

 

An in vitro prototype system based on a planar array of high brightness, micro-meter sized Light Emitting Diodes (micro-LED) has been used to modulate the activity of cultured Retinal Ganglion Cells (RGC). ChR2 expression in these cells has been achieved using the Amaxa® Nucleofector® electroporation technology.

 

Results:

 

We demonstrate the effectiveness of this system to stimulate trains of action potentials in retinal ganglion cells. It can target many cells simultaneously to provide the necessary resolution to encode meaningful images. The system has been developed to enable the capture and processing of the visual scene to control the stimulation of the RGC’s.

 

Conclusions:

 

The ability to optically stimulate photosensitised retinal ganglion cells offers the possibility of an optogenetic retinal prosthesis. We have been developing scalable, optoelectronic equipment that provides the resolution needed to return functional vision to the user.Figure : Optical Stimulation of a RGC(Left) Spiking from a retinal ganglion cell generated in response to light pulse (Right) Retinal Ganglion Cell expressing ChR2 channels (fused with YFP fluorescent label)  

 

Keywords: retina