GURUNANAK INSTITUTIONS

TECHNICAL SEMINAR

By

C.Prashanth Kumar

ECE,11-424

Artificial

Eye

Contents:

- How human eye works?

- Diseases related to eye

- What is Artificial Silicon Retina?

- Implantation

- Working

- What is Bionic Eye?

- Components

- Working

- Results & Advantages

- Limitations & Drawbacks

- Conclusion

Working of human eye :

-The eye is one of the most important

organs of the body.Before we learn

about ASR,it is important to know the

working of natural retina.

-The light coming from an object enters

the eye through cornea and pupil and

forms inverted image on the retina.

-The light sensitive cells of the retina

gets activated with the incidence of light

and generate electric signals. These

electric signals are sent to the brain by

the optic nerves and the brain interprets

the electrical signals in such away that

we see an image .

-There are mainly two kinds of diseases related to eye:

Age related macular degeneration(AMD or ARMD): Macular

degeneration, often age-related macular degeneration , is a medical

condition that usually affects older adults and results in a loss of vision

in the center of the visual field (the macula) because of damage to the

retina.

Retinitis Pigmentosa: It is a chronic hereditary eye disease

characterized by black pigmentation, gradual degeneration of the retina

and causes narrowing of vision.

What is ASR ?

A visual prosthesis, is an experimental visual device intended to

restore functional vision in those suffering from partial or

total blindness.

-In 1983 Joao Lobo Antunes, a world renowned Portuguese

doctor, implanted a bionic eye in a person born blind.

- The brothers Alan Chow and Vincent Chow have developed a

microchip containing 3500 photo diodes, which detect light and

convert it into electrical impulses called ASR.

Size of an ASR:

- The ASR is an extremely tiny device.It has a diameter of just 2mm

and is thinner than human hair.

Implantation:

- Surgeons make three tiny incisions no

larger than the diameter of a needle in the

white part of the eye.Through these

incisions,they introduce a miniature cutting

and vaccuuming device that removes gel in

the middle of eye and replaces it with

saline.

- Then,a pinpoint opening is made in the

retina through which they inject fluid to lift

up the portion of retina from the back of

eye,which creates a small packet in the sub

retinal space for the device to fit in.Finally

the retina is then released over the ASR.

Working of ASR :

- The ASR microchip is a 2mm in diameter silicon chip (same concept as

computer chips) containing ~5,000 microscopic solar cells called

"microphotodiodes" that each have their own stimulating electrode.

- It detects light and convert it into electrical impulses, which stimulate

healthy retinal ganglion cells and these pulses are sent brain by optic

nerve.

Power needed for ASR :

-For any microchip to work it needs power, and the amazing thing

about the ASR is that it receives all of its needed power from the light

entering the eye.

-This means that with the ASR implant in place behind the retina, it

receives all of the light entering the eye. This solar energy eliminates

the need for any wires, batteries or other secondary devices to supply

power.

Images Shows which type of images are seen to a blind

person using ASR Technology :

BIONIC EYE

History of BIONIC EYE :

- Dr.Mark Humayun, Dr. Eugene Dejuan along with few more scientists

demonstrated that a visually impaired person could be made to see light by

stimulating the optic nerves behind the retina with electrical impulses.This test

proved that the nerves behind retina still functioned even when the retina had

degenerated.

- Based on this scientists set out to create a devise that could translate images

to electrical pulses that could restore vision.

- Groups of researchers have found that blind people can see spots of light

when electrical currents stimulate cells,following the experimental insertion of

an electrode device near to the retina.

- The main target of the research was:

_small enough to be implanted in the eye.

_supplied with a continuous source of power.

_bio-compatible with eye tissues and its surroundings.

Components required for BIONIC EYE:

Camera mounted on eye glases:

-This camera is placed on the goggles.

The camera captures the image and converts it

into pixels of black and white.

- The battery required for this is provided from

the video processing unit.

Video processing unit (VPU) :

- Video Processing Unit is device which

simplifies the image as spots of light and

then reduces the image to the number of

photodiodes.This is connected to goggles

through conneccting wires.

Eye implant :

- These are the MICROELECTRODES

array.

- 68 flat platinum electrodes of 1mm

diameter are pierced through the holes

into the nucleus of neurons of the

occipital lobe.

Working of BIONIC EYE :

-The camera mounted on a pair of eyeglasses, captures the scene in

front of the wearer and sends it to VPU on the patient's belt.

-The processor translates the image into a series of signals that the

brain can understand. The group of wires pass the processed image

which are generated by the processor to the transmitter.

-RF trasmitter sends the signal to the RF receiver which is near the eye

implant wirelessly.

- Receiver attains the transmitted signal and demodulation is done

which is sent to the microelectrode strip.

- These electrodes converts it into electrical pulses and provide it to the

optic nerve.

Role of BIONIC EYE in tracking

objects :

- It provides information about the edges of

images rather than a whole picture. Edge

information is usually sufficient for detecting

and tracking objects.

- The top image shows the raw output of the

retina chip.

- The middle one is a picture processed from

it.

- The third one shows how moving face

would appear.

Results and Advantages :

- Identify the location or movement of objects and people.

Recognize large letters, words or sentences.

- Helps in other activities of daily life, such as detecting street

curbs and walking on a sidewalk without stepping off.

- Ability to perform visual tasks demonstrated in many patients.

- Upgradable external hardware and software to benefit from

future innovations.

- The brain has an amazing ability to adapt to new input and to

improve his or her understanding of what is being “seen” via an

artificial vision system.

Limitations and Drawbacks :

- Repairing is difficult if any of the devices got damaged.

- Those who lost their visions due to other reasons could not use this

device.

- It may not work for people blinded as children or as infants,

because the visual cortex do not develop normally.

- Surgery is required to implant the electrode array.

The approximated cost of the device is $70,000.

Conclusion :

- Revolutionary piece of technology.

- The first useful artificial eye is now helping a blind man walk safely

around and read large letters.

- Good news for AMD and Retinitis Pigmentosa patients.

-Research is going for high resolution images.

THANK YOU !!

References :

-Wikipedia

-Google.com

-Encyclopedia

-Optobionics.com