Charles Bonnet Syndrome Causes Blind People to "See Things"

April 03, 2012
A 75-year-old woman with virtually complete vision and hearing loss from Usher syndrome went to the ophthalmology department at the Hospital Clinico San Carlos in Madrid, Spain, a while back, reporting some curious symptoms. At night she was hearing cabaret music and seeing what the doctors called “complex visual hallucinations.”

After a thorough neurological examination, the doctors determined that she was “aware of her reality” and wasn’t suffering from any mental illness or neurological problems. They concluded that her unusual sensory experiences were caused by a form of Charles Bonnet syndrome.

The doctors’ findings were published in the March 6, 2012, online edition of the European Journal of Ophthalmology.

Named after the Swiss philosopher who first described the condition in the 1700s, Charles Bonnet syndrome occasionally affects people who are blind or have very little vision. It occurs in much the same way that people with lost limbs continue to perceive sensations in them. The reason for these phenomena is that the region of the brain that was controlling the limb — or, in this case, vision — continues to be active after the loss.

The case of the elderly woman with Usher syndrome was different from previously reported cases, because she was also experiencing auditory hallucinations. Her doctors referred to her condition as “Charles Bonnet plus syndrome.”

People with Charles Bonnet syndrome have reported “seeing” a variety of images, from babies to landscapes to buildings. Sometimes the images seem very real, other times abstract, like cartoons or patterns. The condition often occurs when someone is sitting quietly in dim lighting, and goes away when the lighting gets brighter, or they become more active.

While the syndrome can be frightening, it isn’t dangerous. However, a person experiencing hallucinations should see a doctor to rule out more serious underlying neurological problems or possible side effects from medications.