Blind World


Charles Bonnet syndrome.
When the Vision Goes, the Hallucinations Begin.





September 14, 2004.

By SUSAN KRUGLINSKI,
The New York Times.




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."




End of article.



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