bionic eyes - hope for the blind

8/7/2019 Bionic Eyes - Hope for the blind

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Paper Presentation On

Bionic Eyes - Hope for the blind!

-K. Harish Kumar, M. Santosh Kumar, T.Sanjeev Kumar

Abstract

Technology has done wonders for the mankind. We have seen prosthetics that helped

overcome handicaps. Bio medical engineers play a vital role in shaping the course of these

prosthetics. Now it is the turn of Artificial Vision through Bionic Eyes.

Chips-designed specifically to imitate the characteristics of the damaged retina, and the

cones and rods of the organ of sight are implanted with a microsurgery.

Whether it be Bio medical, Computer, Electrical, or Mechanical Engineers all of them

have a role to play in the personification of Bionic Eyes. This multidisciplinary nature of the new

technology has inspired me to present this paper.

There is hope forthe blind in the form of Bionic Eyes. This technology can add life to their

vision less eyes!

Introduction:

There is no lovelier way tothank God for your sight

Than by giving a helping hand

To those in dark.There is no replacement for human sight. It is simply incomparable because of its capacity

to see. Our life is full of pictures we daily see. Life without sight is dark. And blind people lead

dark lives. As capable human beings, we need to do something more than just helping a blind

person cross the road.

Belonging to the community of engineers there is no frontier that we cannot conquer. If

scientists give birth to ideas, then it is we engineers who put life into those ideas. Today, we have

every tool in our hand. The ball is in our court! It is our turn now, to return what mankind has given

us. What about bestowing sight for the blind? There is no magic wand to do this in a jiffy. But yes!

We certainly know the magic route to reach our goal: Science and Technology.

Today, we talk of artificial intelligence that has created waves of interest in the field of

robotics. When this has been possible, why not artificial vision? It is with this dream that I present

this paper on Bionic Eyes. Sooner or later, this shall create a revolution in the field of medicine.


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It is important to know few facts about the organ of sight i.e, the Eye before we proceed

towards the technicalities involved.

How are we able to see?

Having seen the anatomical part of human eye, lets try to know as to how we are able to see how

is an image being formed?

For vision to occur, 2 conditions need to be met:

1.An image must be formed on the retina to stimulate its receptors (rods and cones).

2.Resulting nerve impulses must be conducted to the visual areas of the cerebral cortex for

interpretation.

Four processes focus light rays, so that they form a clear image on the retina

1.refraction of light rays

2.accommodation of the lens

3.constriction of the pupil

4.convergence of the eyes

How is vision impaired?

Damage or degeneration of the optic nerve, the brain, or any part of the visual pathway

between them, can impair vision. For example, the pressure associated with glaucoma can also

damage the optic nerve. Diabetes, already cited as a cause of retina damage, can also cause

degeneration of the optic nerve.

Damage to the visual pathway does not always result in total loss of sight. Depending onwhere the damage occurs, only a part of the visual field may be affected. For example, a certain

form ofneuritis (nerve inflammation), often associated with multiple sclerosis, can cause loss of

only the center of the visual field a condition called scotoma.

A stroke can cause vision impairment when the resulting tissue damage occurs in one of the

regions of the brain that process visual information. For example, damage to an area that process

information about colors may result in a rare condition called acquired cortical color blindness.

This condition is characterized by difficulty in distinguishing any color not just one or two colors

as in the more common inherited forms of color blindness.

A more common treatment for curing blindness has been corneal transplantation. More about it:

Corneal Transplants:


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Surgical removal of opaque or deteriorating corneas and replacement with donor transplants is a

common medical practice. Corneal tissue is avascular; that is, the cornea is free of blood vessels.

Therefore corneal tissue is seldom rejected by the bodys immune system. Antibodies carried in the

blood have no way to reach the transplanted tissue, and therefore long-term success following

implant surgery is excellent.

What are Bionic Eyes?

An artificial eye provokes visual sensations in the brain by directly stimulating different parts of the

optic nerve.

There are also other experimental implants that can stimulate the ganglia cells on the retina or the

visual cortex of the brain itself. There is more concentration given to the production of artificial

retinas.

Here is the description of a Bionic Eye:

Many types of artificial eyes have been designed and research is still going on . There is no

standard model in this case. Researchers are working out different types of concepts. Here are a few

examples:

The prototype devices are 2 millimeters across and contain some 3,500 micro photodiodes.

Placed behind the retina, this collection of miniature solar cells is designed to convert natural light

to electrical signals, which are then transmitted to the brain by the remaining healthy parts of the

retina.


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A Belgian device has a coil that wraps around the optic nerve, with only four points of

electrical contact. By shifting the phase and varying the strength of the signals, the coil can

stimulate different parts of the optic nerve, rather like the way the electron guns in TVs are aimed at

different parts of the screen. The video signals come from an external camera and are transmitted to

the implant via a radio antenna and microchip beneath the skin just behind the ear.

Implants of a microchip, smaller than the head of a pin and about half the thickness of a

sheet of paper were used to remove blindness.

Engineering details of the Bionic Eye:

First, for visually impaired people to derive the greatest benefit from an enhanced-vision

system, the image must be adapted to their particular blind areas and areas of poor acuity or

contrast sensitivity. Then the information arriving instantaneously at the eye must be shifted around

those areas.The thrust of all prosthetic vision devices is to use an electrode array to give the user

perceptions of points of light (phosphenes) that are correlated with the outside world. Thus, to

achieve the expected shift of the image across the stimulating electrode array, the camera capturing

the image must follow the wearer's eye or pupil movements by monitoring the front of the eye

under infrared (IR) illumination. The eye-position monitor controls the image camera's orientation.

If the main image-acquisition camera is not mounted on the head, compensation for head

movement will be needed, as well.

Finally, if a retinal prosthesis is to receive power and signal input from outside the eye via

an IR beam entering the pupil, the transmitter must be aligned with the intraocular chip. The beam

has two roles: it sends power, and it is pulse- or amplitude-modulated to transmit image data. Under

the control of eye movement, the main imaging camera for each eye can swivel in any direction.

Each of these cameras--located just outside the users' field of view to avoid blocking whatever

peripheral vision they might have--captures the image of the outside world and transmits the

information through an optical fiber to a signal-processing computer worn on the body.

The surgery!

This concept of Artificial Vision is also interesting to engineers, because there are a number

of technicalities involved in this surgery apart from the anatomical part.

The microsurgery starts with three incisions smaller than the diameter of a needle in the

white part of the eye. Through the incisions, surgeons introduce a vacuuming device that removes

the gel in the middle of the eye and replaces it with saline solution. Surgeons then make a pinpoint

opening in the retina to inject fluid in order to lift a portion of the retina from the back of the eye,


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creating a pocket to accommodate the chip. The retina is resealed over the chip, and doctors inject

air into the middle of the eye to force the retina back over the device and close the incisions.

During the entire surgery, a biomedical engineer takes part actively to ensure that there is no

problem with the chip to be implanted.

Some facts about Bionic Eyes:

Scientists at the Space Vaccum Epitaxy Centre (SVEC) based at the University of Houston,

Texas, are using a new material, comprising tiny ceramic photocells that could detect incoming

light and repair malfunctioning human eyes. Scientists at SVEC are conducting preliminary tests on

the biocompatibility of this ceramic detector.

The artificial retinas constructed at SVEC consist of 100,000 tiny ceramic detectors, each

1/20th the size of a human hair. The assemblage is so small that surgeons cant safely handle it. So,

the arrays are attached to a polymer film one millimeter in size. After insertion into an eyeball, the

polymer film will simply dissolve leaving only the array behind after a couple of weeks.

The Analogy:

There is a great degree of coherence between the way our eyes function to that of a camera.

Perhaps our eyes had been the inspiration behind the cameras invention. Heres more about it:

From the structural point of view the eye may be compared with a camera. The eyelids act as a

shutter and there is an entrance window for light the cornea; a diaphragm to regulate the aperture

and therefore the amount of light entering the iris; a lens to focus the image; a darkened interior

formed by the choroid, and a light sensitive plate which receives the image the retina.Brain Implants:

There is one more concept similar to Bionic Eyes that is also making waves in the medical

field and that is the use of Brain Implants to remove blindness.

In recent years, progress is being made towards sensory substitution devices for the

blind. In the long run, there could be the possibility of brain implants. A brain implant or

cortical implant provides visual input from a camera directly to the brain via electrodes in

contact with the visual cortex at the backside of the head.

If we try to do a fair and objective comparison between auditory display technology

and brain implant technology it should first be stressed that result of any comparisons can of

course change over time as the respective technologies are further developed and refined.

The Challenges:

There are many very many obstacles to be overcome before Bionic Eyes become a success story.
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Our eyes are perhaps the most sensitive of all organs in the human body. A nano-sized irritant

can create havoc in the eye.

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.

Si based photo detectors have been tried in earlier attempts. But Si

is toxic to the human body and reacts unfavorably with fluids in the eye.

There are many doubts as to how the brain will react to foreign signals

generated by artificial light sensors.

Infection and negative reaction are the always-feared factors. It is

imperative that all precautionary measures need to be ascertained.

Conclusion:

Restoration of sight for the blind is no more a dream today. Bionic Eyes have made this true.

Though there are a number of challenges to be faced before this technology reaches the

common man, the path has been laid. This paper has tried to present the concept of

Artificial Vision through a engineers viewpoint. Engineers play a major role in the design

stage of Bionic Eyes.

It is just a matter of 4-5 years, that the blind will be able to see through these Bionic Eyes;

thanks to Science and Technology.

References:

1. Neural Implants First Bionic Eyes by Victor Chase.

2. Hitting the Nerve (from the New Scientist).

3. Doctors Test Chips in Eyeballs to Restore Sight from azcentral.com

4. www.dobelle.com

5. Anthonys textbook of Anatomy and Physiology - Gary A Thibodeau, Kevin T Patton

6. Science Reporter (December 2004)
http://www.azcentral.com/http://www.dobelle.com/http://www.dobelle.com/http://www.azcentral.com/http://www.dobelle.com/

bionic eyes - hope for the blind

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