[Paleopsych] NYT: When the Vision Goes, the Hallucinations Begin

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When the Vision Goes, the Hallucinations Begin
NYT September 14, 2004
By SUSAN KRUGLINSKI

One day a few years ago, Doris Stowens saw the monsters
from Maurice Sendak's "Where the Wild Things Are" stomping
into her bedroom. Then the creatures morphed into
traditional Thai dancers with long brass fingernails, whose
furious dance took them from the floor to the walls to the
ceiling.

Although shocked to witness such a spectacle, Ms. Stowens,
85, was aware that she was having hallucinations, and she
was certain that they had something to do with the fact
that she suffered from the eye disease macular
degeneration.

"I knew instantly that something was going on between my
brain and my eyes," she said.

Ms. Stowens says that ever since she developed partial
vision loss, she has been seeing pink walls and early
American quilts floating through the blind spots in her
eyes several times each week.

In fact, Ms. Stowens's hallucinations are a result of
Charles Bonnet syndrome, a strange but relatively common
disorder found in people who have vision problems. Because
the overwhelming majority of people with vision problems
are more than 70 years old, the syndrome, named after its
18th-century Swiss discoverer, is mostly found among the
elderly. And because older people are more susceptible to
cognitive deterioration, which can include hallucinations
or delusions, Charles Bonnet (pronounced bon-NAY) is easily
misdiagnosed as mental illness.

Many patients who have it never consult a doctor, out of
fear that they will be labeled mentally ill.

"It is not a rare disorder," said Dr. V. S. Ramachandran, a
neurologist at the University of California at San Diego,
who has written about the syndrome. "It's quite common.
It's just that people don't want to talk about it when they
have it."

Researchers estimate that 10 to 15 percent of people whose
eyesight is worse than 20/60 develop the disorder. Any eye
disease that causes blind spots or low vision can be the
source, including cataracts, glaucoma, diabetic retinopathy
and, most commonly, macular degeneration. The
hallucinations can vary from simple patches of color or
patterns to lifelike images of people or landscapes to
phantasms straight out of dreams. The hallucinations are
usually brief and nonthreatening, and people who have the
syndrome usually understand that what they are seeing is
not real.

Nancy Johnson, a 72-year-old retired schoolteacher from San
Diego whose left eye was removed because of cancerous
tumors, says she is not bothered by the images she sees.

"I see little tiny geometric shapes that all fit together,"
Ms. Johnson said. "Like doodles in the margin of a
notebook. It's sort of interesting and distracting, but
it's not fearful."

But the experience can also be frightening. Ms. Stowens,
for example, said the visions of monsters terrified her.

"I couldn't even speak, my heart was beating so fast," she
said.

Many patients are relieved to hear that what they are
suffering from is simply a vision problem, said Dr. William
O'Connell, a low-vision specialist at the State University
of New York College of Optometry who has seen scores of
patients with Charles Bonnet syndrome.

"I've had patients tell me, 'I thought I might be getting a
brain tumor,' '' he said. "Or 'I thought I might be having
a stroke,' or 'I thought I might have Alzheimer's.' "

Experts say that medication offers no relief to Charles
Bonnet patients, and that in fact there is little that they
can do to stop the hallucinations, besides blinking,
brightening the light in a room or making other changes in
the environment.

In some ways, researchers say, the hallucinations that
define the syndrome are similar to the phenomenon of
phantom limbs, where patients still vividly feel limbs that
have been amputated, or phantom hearing, where a person
hears music or other sounds while going deaf. In all three
cases, the perceptions are caused by a loss of the sensory
information that normally flows unceasingly into the brain.


In the case of sight, the primary visual cortex is
responsible for taking in information, and also for forming
remembered or imagined images. This dual function, Dr.
Ramachandran and other experts say, suggests that normal
vision is in fact a fusion of incoming sensory information
with internally generated sensory input, the brain filling
in the visual field with what it is used to seeing or
expects to see. If you expect the person sitting next to
you to be wearing a blue shirt, for example, you might, in
a quick sideways glance, mistakenly perceive a red shirt as
blue. A more direct gaze allows for more external
information to correct the misperception.

"In a sense, we are all hallucinating all the time," Dr.
Ramachandran said. "What we call normal vision is our
selecting the hallucination that best fits reality."

With extensive vision loss, less external information is
available to adjust and guide the brain's tendency to fill
in sensory gaps. The results may be Thai dancers or
monsters from a children's book.

"The most interesting thing to me," Ms. Stowens said of her
syndrome, "is that this brain of mine keeps telling me
things I don't want to know."

http://www.nytimes.com/2004/09/14/science/14eyes.html