Artificialsiliconretinamain 110919140301 Phpapp02

Artificial Silicon Retina
Acknowledgement
First and foremost I would like to thank God for creating so much, so beautiful that
one would never get bored exploring things.
I believe the best thing that happened to information craz humans was the invention
and advancement of internet.
Internet for me is a repositor of information. It provides the information from around
the world which would have rather taken ears to gather.
So I would like to thank father of internet, Vint Serf for connecting this world
together.
!ut the best thing that happened to internet, which has well now become snonm for
internet, is "Google# .It would have taken a lot of pain to search information on
internet if the concise and appropriate results form $oogle has not been there.
I would like to thank Larry Page and Sergey Brin for their innovative effort to
provide the best search engine ever.
I would also like to thank Wikipedia which has alwas been the first place I go to
know about something. I also thank the people who put in effort to add and organize
information in this free encclopedia which anone can edit. %uch of the information
in this reports are from &ikipedia which explained the concept in such simple wa
that it was worth including in the report.
I would also like to thank Microsoft to have built such powerful &ord 'rocessing
software that helped me to store and organize information. It also helped me to
indentif the numerous spelling and grammar mistakes that I make that would have
otherwise gone (nnoticed.
%ahakal Institute of )echnolog * %anagement,(++AI,
ABSTRACT

!lindness is more feared b the public than an other
ailment. Artificial vision for the blind was once the stuff of science fiction.
!ut now, a limited form of artificial vision is a realit .,ow we are at the
beginning of the end of blindness with this tpe of technolog. In an effort to
illuminate the perpetuall dark world of the blind, researchers are turning to
technolog. )he are investigating several electronic-based strategies
designed to bpass various defects or missing links along the brain.s image
processing pathwa and provide some form of artificial sight.
)his paper is about curing blindness. /inking electronics and
iotec!nology, the scientists has made the commitment to the development
of technolog that will provide or restore vision for the visuall impaired
around the world. )his paper describes the development of artificial "ision
system, which cures blindness to some extent. )his paper explains the
process involved in it and explains the concepts of artificial silicon retina,
cortical implants etc. )he roadblocks that are created are also elucidated
clearl. Finall the advancements made in this sstem and scope of this in the
future is also presented clearl.

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Artificial-vision researchers take inspiration from another device, the
cochlear implant, which has successfull restored hearing to thousands of
deaf people. !ut the human vision sstem is far more complicated than that
of hearing. )he ee is one of the most amazing organs in the bod. !efore we
understand how artificial vision is created, it.s important to know about the
important role that the retina plas in how we see. 6ere is a simple
explanation of what happens when we look at an obCectD
Scattered light from the obCect enters through the cornea.
)he light is proCected onto the retina.
)he retina sends messages to the brain through the optic nerve.
)he brain interprets what the obCect is.

)ig*res +,-./( t!e anatomy of t!e
eye and its pat! "iew
)he retina is complex in itself. )his thin
membrane at the back of the ee is a vital part
of our abilit to see. Its main function is to receive and transmit images to the
brain. )hese are the three main tpes of cells in the ee that help perform this
functionD Rods, 0ones and $anglion 0ells. )he information received b the
rods and cones are transmitted to the nearl 3 million ganglion cells in the
retina. )hese ganglion cells interpret the messages from the rods and cones
and send the information on to the brain b wa of the optic nerve. )here are
a number of retinal diseases that attack these cells, which can lead to
blindness. )he most notable of these diseases are retinitis pigmentosa and
age0related mac*lar degeneration. !oth of these diseases attack the retina,
rendering the rods and cones inoperative, causing either loss of peripheral
vision or total blindness. 6owever, it.s been found that neither of these retinal
diseases affects the ganglion cells or the optic nerve. )his means that if
scientists can develop artificial cones and rods, information could still be sent
to the brain for interpretation. )his concept laid the foundation for the
invention of the ART#)#C#AL V#S#%$ S1ST2M technolog.
3%W T% CR2AT2 ART#)#C#AL V#S#%$4
)he current path that scientists are taking to create artificial vision received a
Colt in 3A@@, when 4r. %ark 6umaun demonstrated that a blind person
could be made to see light b stimulating the nerve ganglia behind the retina
with an electrical current. )his test proved that the nerves behind the retina
still functioned even when the retina had degenerated. !ased on this
information, scientists set out to create a device that could translate images
and electrical pulses that could restore vision. )oda, such a device is ver
close to be available to the millions of people who have lost their vision to
retinal disease. In fact, there are at least two silicon microchip devices that
are being developed. )he concept for both devices is similar, with each
beingD
Small enough to be implanted in the ee
Supplied with a continuous source of power
!iocompatible with the surrounding ee tissue
)ig*res +5-6/ T!e dot ao"e t!e date on t!is penny is t!e f*ll si7e of t!e
Artificial Silicon Retina8
'erhaps the most promising of these two silicon devices is the ART#)#C#AL
S#L#C%$ R2T#$A EASRF. )he ASR is an extremel tin device. It has a
diameter of Cust 5 mm E.B?@ inchF and is thinner than a human hair. In order
for an artificial retina to work it has to be small enough so that doctors can
transplant it in the ee without damaging the other structures within the ee.
$roups of researchers have found that blind people can see spots of light
when electrical currents stimulate cells, following the experimental insertion
of an electrode device near or into their retina. Some patients even saw crude
shapes in the form of these light spots. )his indicates that despite damage to
cells in the retina, electronic techniGues can transmit signals to the next step
in the pathwa and provide some form of visual sensation. Researchers are
currentl developing more sophisticated computer chips with the hope that
the will be able to transmit more meaningful images to the brain.
3ow does ART#)#C#AL S#L#C%$ R2T#$A works4
)he ASR contains about 9,=BB microscopic solar cells that are able to
convert light into electrical pulses, mimicking the function of cones and rods.
)o implant this device into the ee, surgeons make three tin incisions no
larger than the diameter of a needle in the white part of the ee. )hrough
these incisions, the surgeons introduce a miniature cutting and vacuuming
device that removes the gel in the middle of the ee and replaces it with
saline. ,ext, a pinpoint opening is made in the retina through which the
inCect fluid to lift up a portion of the retina from the back of the ee, which
creates a small pocket in the sub retinal space for the device to fit in. )he
retina is then resealed over the ASR.
)ig*re 9(3ere yo* can see w!ere t!e ASR is placed etween t!e o*ter
and inner retinal layers8
For an microchip to work it needs power, and the amazing thing about the
ASR is that it receives all of its needed power from the light entering the ee.
)his means that with the ASR implant in place behind the retina, it receives
all of the light entering the ee. )his solar energ eliminates the need for an
wires, batteries or other secondar devices to suppl power.
Another microchip device that would restore partial vision is currentl in
development called the artificial retina component c!ip EAR00F, this
device is Guite similar to the ASR. !oth are made of silicon and both are
powered b solar energ. )he AR00 is also a ver small device measuring 5
mm sGuare and a thickness of .B5 millimeters E.BBB?@ inchF. )here are
significant differences between the devices, however. According to
researchers, the AR00 will give blind patients the abilit to see 3B b 3B
pixel images, which is about the size of a single letter on this page. 6owever,
researchers have said that the could eventuall develop a version of the chip
that would allow 5=B b 5=B pixel arra, which would allow those who were
once blind to read a newspaper.
W%R:#$G %) ART#)#C#AL V#S#%$ S1ST2M(
)he main parts of this sstem are miniature video camera, a signal processor,
and the brain implants. )he tin pinhole camera, mounted on a pair of
eeglasses, captures the scene in front of the wearer and sends it to a small
computer on the patient.s belt. )he processor translates the image into a
series of signals that the brain can understand, and then sends the information
to the brain implant that is placed in patientHs visual cortex. And, if
everthing goes according to plan, the brain will IseeI the image.

)ig*res +;-</ ill*strating t!e AV S1ST2M8
/ight enters the camera, which then sends the image to a wireless wallet-
sized computer for processing. )he computer transmits this information to an
infrared /24 screen on the goggles. )he goggles reflect an infrared image
into the ee and on to the retinal chip, stimulating photodiodes on the chip.
)he photodiodes mimic the retinal cells b converting light into electrical
signals, which are then transmitted b cells in the inner retina via nerve
pulses to the brain. )he goggles are transparent so if the user still has some
vision, the can match that with the new information - the device would
cover about 3BJ of the wearerHs field of vision.
)he patient should wear sunglasses with a tin pinhole camera mounted on
one lens and an ultrasonic range finder on the other. !oth devices
communicate with a small computer carried on his hip, which highlights the
edges between light and dark areas in the camera image. It then tells an
adCacent computer to send appropriate signals to an arra of small electrodes
on the surface of patientHs brain, through wires entering his skull. )he
electrodes stimulate certain brain cells, making the person perceive the
specks of light. )he shifting patterns as scans across a scene tells him where
light areas meet dark ones, letting him find the black cap on the white wall,
for example. )he device provides a sort of tunnel vision, reading an area
about the size of a card 5 inches wide and @ inches tall, held at arm.s length.
A&VA$C2M2$TS #$ CR2AT#$G ART#)#C#AL V#S#%$(
0eramic optical detectors based on the photo-ferroelectrics effect are being
developed for direct implantation into the ees of patients with retinal
dystrop!ies. In retinal dstrophies where the optic nerve and retinal ganglia
are intact Esuch as Retinitis 'igmentosaF, direct retinal implant of an optical
detector to stimulate retinal ganglia could allow patients to regain some sight.
In such cases additional wiring to the brain cortex is not reGuired, and for
biologicall inert detectors, surgical implantation can be Guite direct. )he
detector currentl being developed for this application is a thin film
ferroelectric detector, which under optical illumination can generate a local
photocurrent and photo voltage. )he local electric current generated b this
miniature detector excites the retinal neural circuit resulting in a signal at the
optic nerve that ma be translated b the cortex of the brain as Iseeing lightI.
4etectors based on 'b/aKr)i1
9
E'/K)F and !i7%n1
9
E!7%1F films
exhibit a strong photo response in visible range overlapping ee response
from 9@B nm to >=B nm. )he thin film detector heterostructures have been
implanted into the ees of rabbits for biocompatibilit test, and have shown
no biological incompatibilities.
)he bionic devices tested so far include both those attached to the back of the
ee itself and those implanted directl in the brain. 'atients with both tpes
of implants describe seeing multiple points of light and, in some cases, crude
outlines of obCects. 'lacing electrodes in the ee has proved easier. 4uring
the past decade, work on these retinal implants has attracted growing
government funding and commercial interest. Such implants zap electrical
signals to nerves on the back of the ee, which then carr them to the brain.
6owever, since these devices take advantage of surviving parts of the ee
the will help onl the subset of blind people whose blindness is due to
retinal disease, b some estimates about 9BL of the blind. %oreover,
scientists don.t believe an implant could help those blind since birth,
because their brains never have learned to recognize vision.
W!at lind patients wo*ld not e ale to *se t!is de"ice?
&e believe the device will be applicable to virtuall all patients who are
blind or who have ver low vision. )he onl ones contraindicated would be a
few blinded b serious brain damage, or who have chronic infections, etc.
that preclude surgical implants. 'atients who have a small amount of vision
are not contraindicated. 7isual cortex stimulation seems to work the same in
both sighted and blind patients.
B%TTL2$2C:S RA#S2& B1 T3#S T2C3$%L%G1(
,.)he first and foremost thing is the cost .)he miniaturization of eGuipment
and more powerful computers have made this artificial vision possible, but
it.s not cheapD )he operation, eGuipment and necessar training cost M?B,BBB
per patient. And also ma be much higher depending upon the context and
severit.
..It ma not work for people blinded as children or as infants, because the
visual cortex do not develop normall. !ut it will work for the vast maCorit
of the blind -- A@ to AA percent.
5.Researchers caution, however, that artificial vision devices are still highl
experimental and practical sstems are man ears awa. 2ven after the are
refined, the first wave will most likel provide onl crude images, such as
the outline of a kitchen doorwa. It does not function as well as the real ee,
and does not have crstal-clear vision Eas it is onl a cameraF.)he device is a
ver limited navigational aid, and it.s a far cr from the visual experience
normal people enCo.
%T32R R2AS%$S CA'S#$G BL#$&$2SS A$& T32#R
R2M2&#2S(
)he main aim of Artificial 7ision is to restore some degree of sight to the
profoundl blind. Since blindness can result from defects at man different
points along the visual pathwa, there are accordingl a wide variet of
proposed models for an IArtificial 2eI.
)he earliest stage of visual processing is the transudation of light into
electrical signals b the p!otoreceptors8 If this is the onl process that is
interrupted in a blind individual, he or she ma benefit from a S*0Retinal
Prost!esis, a device that is designed to replace onl the photoreceptors in the
retina. 6owever, if the %ptic $er"e itself is damaged, the onl possibilit for
restoring sight is to directl stimulate the visual cortex. Cortical prost!esis
is designed specificall for this task. Although the categories presented
account for most of the research in Artificial 7ision, there are a few more
exotic techniGues being developed. 1ne of these is the Bio3yrid #mplant a
device that incorporates living cells with man-made elements. Regardless of
the specific design, all of these devices are working towards the same goal--
a permanent replacement for part of the human visual sstem.
P3%T% GALL2R1(

Vincent C!ow and !is rot!er &r8 Alan C!ow- in"entors of t!e Artificial Silicon Retina c!ip- pose
for a p!otograp! A*g*st ;- .==, in W!eaton- #L

&octors P*lido- Peyman- and C!ow pose for a p!otograp! after a s*ccessf*lly implanting
an artificial silicon retina c!ip in a patient>>s eye A*g*st ;- .==, in W!eaton- #L8

A magnified image of an eye wit! age0related mac*lar degeneration A*g*st ;- .==, in
W!eaton- #L8
A magnified image of an eye wit! retinitis pigmentosa A*g*st ;- .==, in W!eaton- #L8
C%$CL'S#%$(
)he electronic ee is the latest in high-tech gadgets aimed at helping millions
of blind and visuall impaired people. Although the images produced b
the artificial ee were far from perfect, the could be clear enough to
allow someone who is otherwise blind to recognize faces. )he first
useful artificial ee is now helping a blind man walk safel around and
read large letters. Several efforts are now underwa to create vision in
otherwise blind ees. &hile technicall exciting, much more work in
this area needs to be completed before anthing is available to the
maCorit of patients. Research is ongoing in two areasD cortical implants
and retinal implants. )here is still an enormous amount of work to be
done in developing artificial retinas. In recent ears, progress is being
made towards sensory distri*tion devices for the blind. In the long
run, there could be the possibilit of brain implants. A brain implant or
cortical implant provides visual input from a camera directl to the brain
via electrodes in contact with the visual cortex at the backside of the
head.
B#B#L#%GRAP31(
B%%:S(
,86umaun %S, de +uan 2 +r., 4agnelie $, et al. 7isual perception
elicited b electrical stimulation of retina in blind humans. Archives
of 1phthalmologN vol 33;.
.8 ?Artificial Vision for t!e Blind y Connecting a Tele"ision
Camera to t!e Brain@ ASAIO Journal 2000
References( www8artificial"ision8com
!ttp(AAwww8life8comAimage
www8!owst*ffworks8com
www8wikipedia8org
www8itotd8com

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Artificial Silicon Retina

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