From Diana J. Choyce
Dec 20 - 26, 1999
Science and Technology have grown so fast, that the lines
between them have been crossing more and more. But this is a good thing because in
co-operation the two have made many incredible advances for man and his environment.
Recent research has made some remarkable breakthroughs in helping the blind. Though it
will be quite some time before a full cure is found, these advances come as a gift to
those who can't see. In a dark world, even a shadow or shade of light is better than
nothing at all.
Our eyes work similar to that of a camera. The lens focuses images onto
the retina which stimulates special nerve cells called retinal ganglions. They then send
the information on to the optic nerve which is connected to the brain. That is where the
picture of what we are seeing is developed. Over10 million people worldwide suffer from
retinal degenerative diseases such as age-related macular degeneration (AMD) and retinitis
pigmentosa (RP). In those with a healthy retina, photoreceptors start the signalling to
the brain in response to light. These receptors are almost completely absent in those with
RP or AMD. However many of the nerve cells remain active and attached. So the new approach
is to replace photoreceptor function with electrical stimulation of these nerves.
The new technology uses a small video camera in a set of goggles to
send images to the microchip fastened to the back of the retina. Electrodes on the chip
form an image that can stimulate the retina and be "seen'' by blind people. An
implanted chip, and its bank of 5000 solar cells, converts the light into electrical
signals that travel through the optic nerve to the brain, and are interpreted as an image.
Currently the device displays only black and white images. "The beauty of it is that
you're hooked up to the most powerful computer in the world, which is the human brain,''
said Dr. Mark Humayun, an ophthalmologist at Johns Hopkins Hospital's Wilmer Eye
Institute. If planned animal and human trials are successful, the eye chip could be
available in the next five years. Dr. Humayun says the prosthetic eyes are most useful for
people who had sight at one time. Or those whose eyesight is lessening due to a
degenerative eye disease.
The full system hasn't been tried with humans yet, but its various
components have been undergoing tests for the last ten years. To date, seventeen patients
have been fitted with the electrodes that are inserted directly into the retina. Many have
been able to see light and a few have seen colours and light forms. One patient,
72-year-old Harold Churchey of Sharpsburg, Md., was able to recognize that a series of
lighted dots formed the letter H. "From the very first time they put that first probe
in my eye, I knew they were on the right track,'' he said. Harold and his brother Carroll
are identical twins who are both legally blind. They are both participating as volunteers
in the research. "There's a lot of blind people in this whole world, a lot of blind
people, and through this procedure, if I can help them, I'm all for it. I can't wait till
I can see my wife, and my son and my grandson", said Harold Churchey, crying.
These tests are done as short term transplants. They are done over a
two to three hour period, and the implant is then removed. The implants are not
biocompatable and are therefore not safe for more long term sessions. Scientists have made
this a priority in their studies. The ability to leave the implants in for longer periods
would help the research progress much more rapidly. The research teams involved in ongoing
projects come from Massachusetts Institute of Technology (MIT), Johns Hopkins Hospital's
Wilmer Eye Institute, and the University of Bonn in Germany.
There are several obstacles that remain to be solved. One is that the
chip being used can only transmit an image of one hundred pixels or points. Scientists
hope to develop one that will transmit 500 pixels or more. The other problem is a safe and
secure way to attach the microchip to the retina. The fabric of the retina is as delicate
as wet tissue paper. Also it must fit very tightly in order to prevent eye fluids from
corroding it. And its power source must be strong enough but sensitive enough not to heat
up and damage the eye. Scientists are saying that one shouldn't expect this to be a cure
for blindness. "It would help their quality of life because they could make out the
general forms of a spouse or a child,'' he said. "But it's not going to give them the
kind of high-acuity vision that you and I have.''
What a wonderful feat of technology this could be, if the blind can be
made to see again. Most people agree that losing their sight would be the worst handicap
to live under. If man would spend a little more money on this type of research, instead of
the more foolish, we could then say we are truly working towards man's good. To enable
people like Harold and Carroll Churchey to see their families again would indeed be a
great accomplishment.
