[Editors] MIT research gives hope to blind children

[Elizabeth Thomson]

MIT News Office
Massachusetts Institute of Technology
Room 11-400
77 Massachusetts Avenue
Cambridge, MA  02139-4307
Phone: 617-253-2700
http://web.mit.edu/newsoffice/www

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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