Charles Bonnet Syndrome: The Mind Plays Tricks with Low Vision Patients
Fried eggs draped over the objects on the desk. Smaller-than-life-sized people in ancient Roman dress streaming out of the television during the morning weather report. Colorful birds flying through the bathroom, roosting on the shower curtain.
Detailed hallucinations of unknown people, faces, buildings, cartoons, children and animals, patterns and designs the viewer knows aren’t real occur spontaneously in about one-third of people who develop low vision due to illness or injury, according to the Royal National Institute of Blind People.
Most people who experience such hallucinations think they have gone mad, because they don’t realize they are experiencing Charles Bonnet Syndrome (CBS). Often, patients remain silent and fearful about their symptoms, which can lead to much quiet suffering (Lighthouse International; Menon, Rahman, Menon, and Dutton 2003). This can develop into clinical depression or an anxiety disorder. Much of this suffering might be avoided if CBS were more widely known by the people most at risk for it and their care team members.
Named for the Swiss naturalist who first described it in 1780 (Bellows), CBS is not widely known. “Physician awareness and empathy are the cornerstones of management” for CBS (Menon, Rahman, Menon, and Dutton 2003). Sadly, too few medical professionals and most patients and their families have never heard of this syndrome, and even fewer know how to approach it with a likely-to-succeed approach. This two-part article will deal with education and empathetic management.
Why does it happen, this “phantom eye” phenomenon? One theory is that the brain is filling in information where there is none due to diminished vision. A parallel can be drawn to the neurological mixup that occurs with phantom limb. The syndrome results in sensation and pain as if a missing limb were still present.
An extension of this theory is offered on the website of the Royal National Institute of Blind People on their website:
Current research seems to suggest that, when you are seeing real things around you, the information received from your eyes actually stops the brain from creating its own pictures. When you lose your sight, however, your brain is not receiving as much information from your eyes as it used to. Your brain can sometimes fill in these gaps by releasing new fantasy pictures, patterns or old pictures that it has stored. When this occurs, you experience these images stored in your brain as hallucinations. CBS tends to begin in the weeks and months following a deterioration in your sight.
For more information about the possible biological mechanisms in CBS, see neurologist Oliver Saks’s informative and charming (though slightly controversial) talk explaining Charles Bonnet Syndrome neurology, which is linked here.
While the description “sees hallucinations” is accurate with CBS, it is not adequate to describe the full experience, nor is it sufficient to help differentiate CBS from other types of hallucinations. The following — especially taken together — are considered distinctive of Charles Bonnet Syndrome: