[Editors] MIT research gives hope to blind children
Elizabeth Thomson
thomson at MIT.EDU
Wed Feb 14 13:51:11 EST 2007
MIT News Office
Massachusetts Institute of Technology
Room 11-400
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Cambridge, MA 02139-4307
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MIT research gives hope to blind children
--Case study shows that those who once
were blind, can learn to see
--Team launches humanitarian initiative
to expand reach of eye care facilities in India
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For Immediate Release
WEDNESDAY, FEB. 14, 2007
Contact: Elizabeth A. Thomson, MIT News Office
Phone: 617-258-5402
Email: thomson at mit.edu
PHOTOS AVAILABLE
CAMBRIDGE, Mass.--How does the human brain "learn" to see? If the
brain is deprived of visual input early in life, can it later learn
to see at all?
MIT researchers are exploring those questions by studying some unique
patients-people who were born blind, or blinded very young, and later
had their sight restored.
Doctors have long believed that children who were blind during a
"critical period" early in life had little hope of learning how to
see even if vision were later restored, so they were reluctant to
offer potentially risky surgical treatments such as cataract removal
to children older than 5 or 6.
However, in a recent case study, the MIT researchers found that a
woman who had her vision restored at the age of 12 performed almost
normally on a battery of high-level vision tests when they studied
her at the age of 32. The study appears in a recent issue of
Psychological Science.
The new research "shows that the brain is still malleable" in older
children, says Pawan Sinha, senior author and associate professor of
brain and cognitive sciences at MIT. This knowledge could benefit
thousands of blind children around the world, particularly in
developing nations, who were previously thought to be too old to
receive eye treatment.
The MIT researchers found their case study subject in India, where
childhood blindness is a huge problem, and where Sinha recently
launched a humanitarian initiative, Project Prakash, to help expand
the reach of eye care facilities.
About 450,000 children in India are blind, and many of those cases
are preventable. Most of the affected children live in remote areas
where eye care is not available, so conditions that could be easily
treated, such as cataracts, vitamin A deficiency or conjunctivitis,
often lead to blindness.
In many such cases, blindness can be deadly: Blind children in India
have a 15-year-shorter life expectancy than sighted children, and
half of them die before the age of 5, according to Sinha. "Blindness
essentially hastens death," he said. Some blind children are able to
go to school, but "many live out their lives entirely dependent on
other people's charity."
Through Project Prakash (Prakash means "light" in Sanskrit), the MIT
researchers are making eye care available to blind children who would
otherwise go untreated. The project has both humanitarian and
scientific benefits-after treatment, the researchers study the
children's progress, gaining insight into how the brain learns to see.
In the Psychological Science paper, the researchers studied a subject
they encountered serendipitously-a 32-year-old woman who had had her
sight restored at the age of 12. Known by her initials, S.R.D., the
woman is the first subject of this kind who has been extensively
studied, but there are other patients like her in India, says Yuri
Ostrovsky, first author of the paper and a graduate student in brain
and cognitive sciences.
Before her surgery, S.R.D. could distinguish between light and dark,
but could not make out form or pattern. Twenty years after the
surgery, S.R.D.'s visual acuity was only 20/200, but the researchers
were surprised to find that she showed normal or near normal
abilities on most tests of high-level vision, including recognizing
objects and faces, judging depth order and matching 2D and 3D shapes.
One task where she did not do well was the gaze-estimation test,
where she based her answers on where people's heads were pointed, not
where their eyes were looking. She also seemed to take longer to
perform some of the tasks, and she had trouble visualizing objects
with her eyes closed, said Ostrovsky.
S.R.D. had no explicit training after her surgery, so she had to
learn by experience. Because of the 20-year lag between her sight
restoration and initial testing by the researchers, they don't know
how much time it took her to reach her present level. "It's hard to
get the full picture," said Ostrovsky.
Still, the findings have significant implications for the idea of a
"critical period" for learning how to see, says Sinha. There are few
data from human subjects regarding such a critical period, but
studies with other animals such as kittens have suggested that visual
recovery is very limited following a few initial months of rearing in
complete darkness. Extrapolating these findings to humans would lead
one to conclude that treating blind children after a few years of age
would be of very limited use.
However, evidence from the case of S.R.D. and others suggests that
the visual cortex retains its plasticity, or ability to learn new
functions, well into childhood.
Those early results have already had an impact on how doctors view
childhood blindness. Ophthalmologists working with the MIT team in
India are now more willing to treat older patients, which they
previously thought would be hopeless.
"Before our collaboration with them, they would be very reluctant to
treat children older than 5 or 6 years of age, but now they are much
more willing to identify older children and treat them," Sinha said.
After completing their case study, the researchers received the
distressing news that S.R.D. had met with an accident while taking
her 9-year-old daughter to the eye clinic. She fell while getting off
of a bus and was pulled under the wheels, and died of her injuries.
The researchers plan to contribute funds to help her daughter, who is
now living by herself in a hostel for the blind, and other blind
children who often end up neglected by society.
MIT graduate student Aaron Andalman of brain and cognitive sciences
is also an author on the Psychological Science paper. The research
was funded by the Merck Scholars Fund and the National Eye Institute.
In other ongoing studies, the researchers hope to track the precise
order and mechanism of visual skill development following sight
restoration.
--END--
Written by Anne Trafton, MIT News Office
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