retinal prostheses anthony burkitt presentation

8/7/2019 Retinal Prostheses Anthony Burkitt Presentation

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Retinal Prostheses for People

who are Vision Impaired

Deafblind Conference, 28th April 2010

Anthony N. BurkittElectrical & Electronic EngineeringThe University of Melbourne

Retinal Prosthesis (Bionic Eye)

Components:

Camera: mounted on glasses externally

Vision processing unit: Converts image to electrical

impulses (worn externally)

Transmitter: Sends data and power (worn externally)

Receiver unit: Receives data and power (implanted)

Electrode array: Delivers electrical impulses to retina

(implanted)


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Bionic Eye

Image

Processor

Power

Supply

Power/Data

Transmitter

Camera

Implanted

Receiver/Stimulator

Battery

IMAGE

PROCESSOR

Transcutaneous

Power/Data LinkIMPLANT

Power

Data

Telemetry

Bionic Eye


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The Eye

Retinal Diseases

light


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The clinical need

Retinitis Pigmentosa (RP)- Leading cause of inherited blindness.

- 1.5 million people affected worldwide.

- 25% of RP patients legally blind

Age-related MacularDegeneration (AMD)

- Major cause of severe vision loss inWestern countries.

- 1/1000 people affected world wide.

- Currently costs Australia $2.6bn p.a.

- 1-2% of AMD patients legally blind

Two major retinal diseases are the target for a bionic eye.

International approaches

German VC funded founded 2003

Have conducted preclinical trials(Zrenner group)

Second-Sight

US VC & Govt funded

Clinical trials conducted

Commercial

German-Swiss VC &Govt funded

Academic

Optoelectronic Retinal Prosthesis

(Palanker group)

Mass Eye and Ear / MIT

(Rizzo & Wyatt group)

Intelligent Medical

Implants (IMI)

France: Institut de la Vision Paris

Japan: Medicine, Nagoya Uni

Korea: Seoul Artificial Eye Center


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BVAs Wide-View Neurostimulator

(suprachoroidal)

TRANSMITTER COILCAMERA

98 ELECTRODEARRAY

98 ELECTRODEARRAY

CHOROIDSCLERA

VISION PROCESSOR

ELECTRONICS UNIT

CHOROID

SCLERA

WHAT WILL I SEE? WHAT WILL I LOOK LIKE? WHAT IS IMPLANTED?

Normal

vision:

Anticipated

vision:

A wide-view neurostimulator provides mobility through

navigation and avoidance of obstacles

A wide-view neurostimulator provides mobility through

navigation and avoidance of obstacles

BVAs High-Acuity Neurostimulator (epi-retinal)

TRANSMITTER COIL

CAMERA

1000 ELECTRODE ARRAY &SIMULATOR

WIRELESS TRANSMISSION

VISION PROCESSOR

32 x 32 ARRAY

Second

Prototype

vision

WHAT WILL I SEE? WHAT WILL I LOOK LIKE? WHAT IS IMPLANTED?

A high-acuity neurostimulator provides face recognition

and large-print reading ability

A high-acuity neurostimulator provides face recognition

and large-print reading ability


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Implant placement in eye

Phosphene Vision

Electrical stimulation produces

phosphenes.

Phosphene vision:

Induced perception of light bymeans other than light entering

the eye.


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Electrical stimulation

Electrical stimulation

Electrical pulses

Which electrode

Number of electrodes

Amplitude &Frequency

Perception

Phosphenes

Position

Acuity

Brightness

Retinotopic map of visual field

What do you see here?

16 Phosphenes


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64 Phosphenes


1000 Phosphenes



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Original Picture


16 Phosphenes

Can you read this?


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64 Phosphenes

Can you read this?

1000 Phosphenes

Can you read this?


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Original Text

Can you read this?

The key scientific challenges

1. Electrode-neural interface

Ability to stimulate neural tissue reliably

Stable long-term interface, without causing damage

2. Localized visual perception

Charge distribution in localized area within retina Evoke multiple phosphenes across the visual field in blind humans

3. Long-term biostability and encapsulation

Safe inert materials

Life-long hermeticity


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Core Device Development Stream

Common hardware interface to implant:

External vision processor:

Image capture, stimulus

encoding, wireless power and

data transfer.

Implanted receiver-controller:

A behind-the-ear implant to

receive power and data

wirelessly.

Ocular implant device:

Implanted near site of

stimulation on sclera.

Wide-View Neurostimulator Electronics

98 stimulation channels toprovide mobility and objectrecognition.


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Multi-layered, biologically-inert,high-density electrode arraysmade from Pt and medical gradesilicone.

Supra-choroidal placementprovides robust tissue interfacingon all electrodes

Laser-induced surfacemodifications electrodes improvecharge-carrying capacity.

Wide-View Neurostimulator Electrodes

Hermeticity is key to devicelongevity

Material composition of the

hermetic feedthrough consists ofonly Al2O3 ceramic and platinumconductors.

98 channels are readily achievedwith this approach.

Wide-View Neurostimulator Encapsulation


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High-Acuity Neurostimulator

Key issues:

Electrode-tissue interface: safe and high-acuity (e.g. face recognition).

Wireless power and data: safe and efficient.

Implantable microelectronics: low-power and flexible.

Device encapsulation: safe and hermetic.

Strategy:

Advanced materials and newcircuit designs.

World leading expertise inmaterials, microelectronics,wireless data and powertransmission, medicalbionics.

Electrical Stimulation can Restore Vision

Design

boron dopedconductive channel

.

chipsolder ball

electrode tip (Pt, Ir)

diamond

5000 m

~150 m

~ 5 m

60 m

Design

boron dopedconductive channel

.

chipsolder ball

electrode tip (Pt, Ir)

diamond

5000 m

~150 m

~ 5 m

60 m

High density electrode array: >1000 in 5 5 mm.

Close proximity to neurons: < electrode pitch (i.e. < 150 m)

Hermetically sealed feed-through

Response threshold < safe charge density

Minimise impedance

Biocompatible


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Electrode-tissue interface: safe and high-acuity

Penetrating

Diamond

Wireless data and power: safe and efficient

Data transceiver < 1 mW

30 mW power deliveredwell within SAR safety limit (2W/kg)using two-pair coils

Intermediatecoils

Secondarycoil

Primarycoilskin

hole thru bone

Data

402MHz

Power5 MHz

penetratingdiamondelectrode

Chronic implantation of electrode materials for biocompatibility evaluation:

Acute study of device performance and surgical safety in animal model

Preclinical Program

5V

20 ms

5V

20 ms

retinaimplant

sclera

biomaterial histopathology

acute implantation OCT imaging electrode voltage electrophysiology


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Stimulation Strategy Program

Computational modelling of concurrent stimulation and retinal activation

Goal: To understand how best to evoke perception of consistent, stable,localised phosphenes in multiple locations


Our patented hex-guard electrode arrangement gives localized potential inretinal models, in vitro, and in vivo.


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Psychophysics (normally sightedindividuals and implant recipients)

Landolt C (broken ring) test

Stimulation Strategy Development -Psychophysics Key psychophysics questions :

How to control visual percepts from a single electrode?

How to control visual percepts from multiple electrodes?

How are the dynamic properties of electrical stimuli perceived?

Wide-view neurostimulator: Developing strategy to encoding distance asbrightness of the image.

High-acuity neurostimulator: Developing strategy to aid facial recognition,object recognition, and hand-eye coordination.

Preliminary data have been obtained with normally-sighted people.


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Surgical Program


Surgical placement studies of high-acuity neurostimulator

In vivo OCT scan of retina

Clinical Program

Objectives:

Accurate pre-operative assessment of potential implant candidates

Appropriate post-operative management of patients to optimiseimplant use

Pre-implant: Use state of the art imaging and visual function analysis for:Determine suitability of potential candidates

Correlate structure and function of retina

Post-implant:

Correlate patient performance with

location of implant


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Clinical Program

Objective is to develop clinical assessment tools for patient suitability, eye

health, visual function, functional vision, visual training, & rehabilitation

CERA, BEI and RVEEH will collaborate to deliver:

Protocols and preliminary data for:

assessment of patient suitability

assessment of eye health & visual function post-implantation

assessment of functional vision in daily life

Fitting software for customisation to individuals

Training and rehabilitation programs post-implantation

Competitive advantage

The Team:

Each world-leaders in their respective fields

Cover all aspects of the design and implementation

Have a solid track record

Work together as a team

The Technology:

Integrated circuit and wireless technology

Implant design, function and encapsulation

Biocompatibility and biological safety techniques

Ophthalmology and eye surgery, inc. clinical expertise

Neural stimulation techniques


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AcknowledgmentsUniversity of Melbourne

Steven Prawer, David Grayden, Frank Caruso

NICTA

Stan Skafidas, Nick Barnes, Hamish Meffin, Mark Halpern, David Ng,Tania Kameneva, Nick Opie, Emily OBrien, Jiawei Yang, Bai Shun,Nang Trann, Clive Boyd

Bionic Ear Institute

Rob Shepherd, James Fallon, Chris Williams, Rodney Millard, MarkHarrison, Mohit Shivdasani, Joel Villalobos

Centre for Eye Research Australia (CERA)

Robyn Guymer, Chi Luu, Penny Allen, Mark McCombe, WilliamCampbell

University of NSW (UNSW)

Nigel Lovell, Gregg Suaning, Torsten Lehmann; Philip Byrnes-Preston

Australian National University (ANU)

Michael Ibbotson

University of Western Sydney (UWS)

John Morley

Thank you!

retinal prostheses anthony burkitt presentation

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