VISUAL PROSTHESIS

By Richard Jones and David Henley

OVERVIEW

Various methods of helping (partially) blind– Brain implant– Seeing with sound– Eye implant

The First Useful Artificial Eye

First implanted in 1978 Allowed ‘Jerry’ to see shades

of grey– Whilst connected to a 10ft

by 7ft, 2 ton computer Now computer weighs 5kg,

and Jerry sees phosphenes

Edge detection algorithms applied to images from camera ‘Jerry’ can navigate New York subway Very limited field of view

Neural Implants

Camera mounted on glasses Computer converts signals

into a form that can be ‘understood’ by the brain

Signal passes down wires into the skull

Connect to an electrode array on the surface of the visual cortex.

Since the 1950s it has been known that stimulating the visual cortex produces phosphenes

The Second Generation

Costs $80,000 US Percutaneous pedestals

- were sunk into both sides of Jens skull

Connected to platinum electronic arrays lying on surface of visual cortex

Phosphene images had to be mapped He drove a car

Alternative methods

Implant described sits on top of the visual cortex– Many neurons are stimulated at once

Richard Normann, is working on device that will be implant into the visual cortex– Lower voltages required, so safer– Much more accurate

Potential to stimulate individual neurons

vOICe DEVICE

Visual Cortex can be stimulated by sound Typically 4000 pixels (vocals) / sec Perception 1000-4000 $2500 (exc training/adaptation) Environment /web etc

HOW IT WORKS

1) Left and Right– Scanning, stereo

2) Top and Bottom– Pitch = elevation

3) Dark and Light– Loudness = brightness

EXAMPLE

Oscilloscope other sound?

EXAMPLE 2

USER THOUGHTS

A late-blinded user of The vOICe commented on August 29, 2002, saying: ``Just sound?.... No, It is by far more, it is sight ! There IS true light perception generated by the vOICe. When I am not wearing the voice the light I perceive from a small slit in my left eye is a grey fog. When wearing the vOICe the image is light with all the little greys and blacks. Yet a definite light image .” …….

ADVANTAGES

Cheap (1/10 implant cost) Fewer risks Quick No implants, no electrodes, no surgery Unobtrusive

DISADVANTAGES

Cannot hear anything else Limited information Brain can only perceive so much sound Training is equivalent to learning a foreign

language

EYE IMPLANT

Artificial Retina Optic nerves and ganglia are intact Partially sighted Infra-red positioning/info/power

EYE IMPLANT

EYE IMPLANT

EXAMPLE OF PIXELATION

CONCLUSON

Field is advancing all the time Three routes mentioned here have adv/disadv Dr. Dobelle has predicted that guide dogs /

Braille will be obsolete by 2100 Geordi LaForge here we come!!!