Bionic eye

Department of ECE Engineering ,SDMCET Dharwad-02

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BIONIC EYE

Maitri Patil

ECE Dept

USN:2SD10EC049

SDMCET


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CONTENTS Human Eye About Bionic Eye Blindness Diseases Artificial Silicon Retina Multi Unit Artificial Retina Chipset Conclusion


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About Bionic Eye Bionic eye’ also called a Bio Electronic eye. An electronic device which replaces functionality of a

part or whole of the eye. The entire electronics system consists of the image

sensors, processors, radio transmitters & receivers, and the retinal chip.


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Human Eye We can see when light from an object move through

space and reach our eyes. Scattered light from the object enters through the

cornea. The light is projected onto the retina. The retina

sends messages to the brain through the optic nerve. The brain interprets what the object is.


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Internal Structure of eye


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More About Human Eye

The important part of an eye that is responsible for vision is retina. The retina is complex in itself.

This thin membrane at the back of the eye is a vital part of your ability to see.

Main function of retina is to receive and transmit images to the brain.


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Human Eye(con’t)

In humans there are three main types of light

sensitive cells in the retina. They are Rod Cells Cone Cells Ganglion Cells

There are about 125 million rods and cones within

the retina that act as the eye’s photoreceptors.


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Human Eye(con’t) Rods are able to function in low light and can create

black and white images without much light. Once enough light is available, cones give us the

ability to see color and detail of objects. The information received by the rods and cones are

then transmitted to the nearly one million ganglion cells in the retina.

These ganglion cells interpret the messages from the rods and cones and send the information on to the brain by way of the optic nerve.


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Blindness Blindness means loss of vision. Rods and Cones are biological solar cells in the retina that

convert light to electrical impulses which travel along the optic nerve to the brain where images are formed.

Without them, eyes lose the capacity to see, and are declared blind.

Degenerative retinal diseases result in death of photoreceptors .

Rod-shaped cells at the retina's periphery are responsible for night vision and cone-shaped cells at its center responsible for color vision.


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Retinal Diseases There are a number of retinal diseases that attack

these cells, which can lead to blindness. The most notable of these diseases are:

1.Retinitis Pigmentosa (RP)

2. Age-related macular degeneration(AMD) Together, AMD and RP affect at least 30 million

people in the world. They are the most common causes of untreatable blindness in developed countries and, currently, there is no effective means of restoring vision


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Retinitis Pigmentosa (RP)

RP is a general term for a number of diseases that predominately affect the photoreceptor layer or “light sensing” cells of the retina.

These diseases are usually hereditary and affect individuals earlier in life.

RP affects the mid-peripheral vision first and sometimes progresses to affect the far -periphery and the central areas of vision. The narrowing of the field of vision into “tunnel vision” can sometimes result in complete blindness.


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Comparison Between Normal and Tunnel Vision


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Age-Related Macular Degeneration(AMD) AMD refers to a degenerative condition that occurs

most frequently in the elderly. AMD is a disease that progressively decreases the

function of specific cellular layers of the retina’s macula.

It degenerates cones in macula region, causing damage to central vision but spares peripheral retina, which affects the ability to read and perform visually demanding tasks.

Although macular degeneration is associated with aging, the exact cause is still unknown


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Comparison Between Normal and AMD Vision


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Bionic Eye : Two Approaches

There are two approaches by which we can implant

a bionic eye: Artificial Silicon Retina – ASR Multi-unit Artificial Retina Chipset - MARC


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Artificial Silicon Retina (ASR) The ASR is a silicon chip 2 mm in diameter and

1/1000 inch in thickness. It contains approximately 3,500 microscopic solar

cells called "microphotodiodes," each having its own stimulating electrode.

These micro photodiodes are designed to convert the light energy from images into thousands of tiny electrical impulses to stimulate the remaining functional cells of the retina in patients suffering with AMD and RP types of conditions.


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ASR (con’t)

The ASR is powered solely by incident light and does not require the use of external wires or batteries.

When surgically implanted under the retina, in a location known as the sub retinal space, the ASR is designed to produce visual signals similar to those produced by the photoreceptor layer.

From their sub retinal location these artificial "photoelectric" signals from the ASR are in a position to induce biological visual signals in the remaining functional retinal cells which may be processed and sent via the optic nerve to the brain.


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Artificial Silicon Retina


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Multi-unit Artificial Retina Chipset (MARC)

The other revolutionary bio electronic eye is the MARC.

This uses a CCD camera input and a laser beam or RF to transmit the image into the chip present in the retina.

Using this, a resolution of 100 pixels is achieved by using a 10x10 array.

It consists of a platinum or rubber silicon electrode array placed inside the eye to stimulate the cells.


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More about MARCMARC basically consists of A secondary receiving coil mounted in close

proximity to the cornea. A power and signal transceiver. A processing chip. A stimulation-current driver and a proposed

electrode array fabricated on a material such as silicone rubber thin silicon or polyimide with ribbon cables connecting the devices.


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MARC (con’t)

An external miniature low-power CMOS camera worn in an eyeglass frame will capture an image and transfer the visual information and power to the intraocular components via RF telemetry.

The intraocular prosthesis will decode the signal and electrically stimulate the retinal neurons through the electrodes in a manner that corresponds to the image acquired by the CMOS Camera.


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Working


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MARC SYSTEM BLOCK DIAGRAM


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Outside Eye:

The video input to the marc system block is given through a CCD camera.

This image is further processed using a PDA sized image processor & to transmit it, we do pulse width modulation in first stage and then ASK modulation is done.

This signal is further amplified using a class E power amplifier and transmitted using RF telemetry coils.


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Inside Eye:

The signal received from the RF telemetry coils is power recovered and then these signal is ASK demodulated and the data and clock is recovered from this signals .

These signals are sent to the configuration and control block of the chip which from its input decode what information has to be sent to each of the electrodes and sends them this data.

The electrodes in turn stimulate the cells in the eye so as to send this stimulation to the brain through optic nerve and help brain in visualizing the image.


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CHALLENGES

Current retinal implants provide very low resolution just a few hundred pixels.

There are many doubts as to how the brain will react to foreign signals generated by artificial light sensors.

Expensive, too clunky and too fragile to withstand decades of normal wear and tear.

There are 120 million rods and 6 million cones in the retina of every healthy human eye. Creating an artificial replacement for these is no easy task.


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On-Going Development:Argus III

The Argus III will work by taking the image from a camera and wirelessly transmitting it to an electronics package. That package will stimulate undamaged retinal tissue using a thin film transistor electrode array.


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Conclusion About 1.5 million people worldwide have Retinitis

Pigmentosa, and one in 10 people over the age of 55 has age related macular degeneration.

The invention and implementation of artificial eye could help those people.

Bionic eye may not restore the vision completely but can help patients to least to find their way, recognize faces, read books, above all lead an independent life .


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References IJCST Paper Artificial Vision-A Bionic Eye Vol 3, Issue

1, Jan-March 2012 James D. Weiland and Mark S. Humayun. "Retinal

Prosthetic Systems for Treatment of Blindness” Frontiers of Engineering 2011: Reports on Leading-Edge Engineering from the 2011 Symposium. Washington, DC: The National Academies Press, 2012, pp. 115–121

www.stanford.edu www.bionicvision.org

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Bionic eye