ARTIFICIAL VISION
Vision for Blind through Artificial
Intelligence
ABSTRACT:
The five senses play a very vital
role in the functioning of the human body. The loss of any of these senses is
regarded as a major setback to many of the basic functions that were previously
performed without any obstruction. Among the five, the loss of sight can turn
out to be a major handicap to human beings. This can be understood perfectly by
a simple experiment. If you try and walk through your own house blindfolded,
you will realize a major difficulty just to cross from one end of the room to
the other. Blindness turns many simple activities into impossible hurdles,
which in turn makes one feel crippled in the world for the sighted. This is the
kind of situation where science has the opportunity to help the human race to
achieve normalcy in vision for all.
There are a few medical procedures
that involve replacing the defective eye with a normal one which is provided by
a donor. Then are other procedures that involve the implant of chips into the
eye, which simulate or mimic the process undergone by the eye during the
generation of vision. This process definitely requires a rather large leap in
the field of bio-electronics. In this paper we deal with the progress made in
developing retinal implants that help regain lost vision in patients who suffer
from retinitis pigmentosa and other related diseases. The basic idea behind
this concept is to implant a silicon chip between the retinal layers and make
the chip to perform its functions. Dr. William Dobelle, Dr. Dick Norman and Dr.
Mark Humayan are the three scientists who gave headway in developing the
artificial vision system.
Introduction:
This paper deals with the diseases
caused to the eye due to retinal damage or degeneration. Here we also discussed
the scientific developments that have taken place during the course of time
that will help in overcoming this problem.
Natural vision:
A sketch of the anatomical components of the
human eye is shown above figure. The main structures are the iris, lens, pupil,
cornea, retina, vitreous humor, optic disk and optic nerve. .
We now know the basic function of
the components of the human eye and how they participate in the vision process.
Light that reflects off the objects around us is imaged onto the retina by the
lens. The retina, consisting of three layers of neurons (photoreceptor, bipolar
and ganglion), is responsible for detecting the light from these images and
then causing impulses to be sent to the brain along the optic nerve. The brain
decodes these images into information that we know as vision. There are a
number of blinding disorders, which are primarily due to photoreceptor or outer
retinal degeneration/destruction.
Since the artificial eyes have not
been developed, they must follow a specific guideline on how the device should
be made and operated. One of the guidelines is the artificial eye must not
affect the eyelids and muscles that surround the eye. It also has to be
lightweight and must allow the eye to support the implant and lock it in place.
The artificial eye must be able to manipulate the eye movements caused by the
rectus muscles. The most important guideline to be followed is that it must be
biocompatible, meaning it must be made up of materials that can be accepted by
the surrounding tissues. This will prevent any infections, pseudo capsule
formation and rejection of the implant.
Creating Artificial Vision:
The current path that scientists
are taking to create artificial vision received a jolt in 1988, when Dr. Mark
Humayun demonstrated that a blind person could be made to see light by
stimulating the nerve ganglia behind the retina with an electrical current.
This test proved that the nerves behind the retina still functioned even when
the retina had degenerated. Based on this information, scientists set out to
create a device that could translate images and electrical pulses that could restore
vision.
Today, such a device is very close
to becoming available to the millions of people who have lost their vision to
retinal diseases. In fact, there are at least two silicon microchip devices
that are being developed, and one has already been implanted in the eyes of
three blind patients. The concept for both devices is similar, with each being:
·
Small enough to be implanted in the eye
·
Supplied with a continuous source of power
·
Biocompatible with the surrounding eye
tissue
Perhaps the more promising of these
two silicon devices is the artificial silicon retina (ASR). The ASR is an
extremely tiny device, smaller than the surface of a pencil eraser. It has a
diameter of just 2 mm (.078 inch) and is thinner than a human hair. There is
good reason for its microscopic size. In order for an artificial retina to work
it has to be small enough so that doctors can transplant it in the eye without
damaging the other structures within the eye
On June 28 and 29, doctors at the University of Illinois
at Chicago Medical
Center and the Central
DuPage Hospital ,
Winfield , Ill.
Artificial Silicon Retina
Preliminary tests from these
FDA-approved surgeries have determined that the device has been biocompatible
with each patient's eyes so far. It could be months before doctors know the
results of these surgeries. They expect that the patients will be able to
regain some vision that would allow them to see rough black and white images,
but not with any detail or color
The ASR contains about 3,500
microscopic solar cells that are able to convert light into electrical pulses,
mimicking the function of cones and rods. To implant this device into the eye,
surgeons make three tiny incisions no larger than the diameter of a needle in
the white part of the eye. Through these incisions, the surgeons introduce a
miniature cutting and vacuuming device that removes the gel in the middle of
the eye and replaces it with saline.
Here you can
see where the ASR is placed between the outer and inner retinal layers.
Next, a pinpoint
opening is made in the retina through which they inject fluid to lift up a
portion of the retina from the back of the eye, which creates a small pocket in
the sub retinal space for the device to fit in. The retina is then resealed
over the 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. As you learned before, light that enters the
eye is directed at the retina. 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.
The
Artificial Eye
An "artificial eye" which
would allow blind people to see is due to be implanted in a patient within the
next few months. The device taps directly into the optic nerve and could
restore some measure of sight to people whose retinas have been damaged or
destroyed. Visual sensations, beamed from a video camera, are created in the
brain by the artificial eye, directly stimulating different parts of the optic
nerve.
A video camera, positioned externally,
transmits the visual sensations via a radio transmitter and microchip to an
implant behind the ear. This is connected to the electrodes on the optic nerve.
Different parts of the optic nerve are stimulated by altering the signals,
similar to the way in which the electron guns in TVs are aimed at different
parts of the screen. The electrode implanted, with wires leading out of the
body to the signal processor, have been able to map camera pixels onto the
corresponding parts of the visual field. This was possible because the
subject was once sighted and knows what it means to "look at"
something. The researchers hope the device will at least allow blind people to
avoid obstacles, though more tests are necessary before the device is implanted.
Most critical is the time it takes to realize they are approaching an object.
If it takes 30 seconds to recognize an obstacle it will be of little use.
Natural
Vs Artificial Vision:
There are a number of blinding
disorders which are caused primarily due to photoreceptor or outer retinal
degeneration/destruction. These are not exclusive to diseases such as retinitis
pigmentosa and age related macular degeneration. Tests have been made regarding
the feasibility of developing a retinal implant/Chip, which could provide form
vision to this subset of blind patients. This visual prosthesis would be
situated in the eye cavity on the retinal surface. It would create the
sensation of seeing light by electrical stimulation of the remaining retinal
cells, which remain relatively intact despite severe photoreceptor loss.
Moreover, by converting images into pixels and then electrically stimulating
the retina by a pattern 3of electrodes, this device would recreate, at least,
in part the visual information/scene.
Natural
Artificial
In an otherwise totally blind eye, controlled
electrical stimulation in patterns can produce vision compatible with limited
mobility and can generate forms in the shape of large letters. The patients
also often described seeing color and direction of movement. The details of
these tests are provided in the following select references. However, as a word
of caution, these results are from short-term tests. Evaluation is being done
to check if these initial encouraging results uphold during more prolonged
tests.
CONCLUSION
Though there has been a major
headway in the development of artificial vision. These conclusions are based
only upon the initial tests performed in laboratories. What is required is
sustained analysis and successful regeneration of vision which in turn will become
the guiding light for many.
References:
1.
www.irit.fr
2.
www.acw.org
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