The Charles Bonnet Syndrome is that visual hallucination event most commonly assumed to be the phenomenon experienced only by those with low vision.
While the elderly are more likely to ex
perience CBS, there have been reported cases of children with CBS visual hallucinations. The problem with defining CBS is that individuals are not likely to report visual events for fear that they will be perceived as old and ‘losing it,’ or crazy and in need of psychological help or medications.
Those who experience CBS hallucinations are those who:
- have recent vision loss, not usually those with long term vision loss,
- have lost the vision in both eyes, (20/100 or worse), and
- are mentally alert, attentive, and understand the hallucinations are not real.
The elderly who experience eye diseases of old age most commonly experience CBS, especially those with age-related macular degeneration. CBS can occur for those with vision loss due to cataracts and diseases that affect the retina, such as glaucoma, diabetic retinopathy, optic neuropathy, retinitis pigmentosa or any disease that causes vision loss due to damage along the visual pathway of the brain.
The hallucinations of Charles Bonnet Syndrome can be simple lines and patterns or complex with animals, people, scenery, and action. Sometimes they are cartoon like, small in size, or grotesque in appearance. They are reported to be brilliant in imagery and blend into the surrounding scenery. They may last a few fleeting seconds or may last for hours. These experiences are episodic and may continue for months to a year. They will eventually end. Those who have these visual experiences may find them disturbing, but do not usually describe them as horrifying or threatening. The images do not interact with them, they are merely observers. Studies indicate that those who live alone are more likely to experience the visual images of CBS. The hallucinations may be triggered by sitting quietly or in bed when there is low light levels. It may also be related to fatigue or stress.
It is believed that visual hallucinations of the CBS are the result of the sudden vision loss due to pathology somewhere along the visual system, which includes the eye, the neural connections, or the occipital cortex part of the brain at the back of the head. The visual hallucinations are analogous to the phantom pain experienced by an amputee. Phantom pain is pain felt in the area where the limb was before it was removed. The brain is filling in the ‘blanks’ where there is no longer any stimulus. The eye doesn’t experience pain with vision loss, but experiences phantom vision. The nerves of the visual system are still firing, in the absence of stimulus, in the form of images. Hallucinations can be called phantom vision!
There are case reports of people, disturbed by the hallucinations, seeking medical help. There is no one direct treatment for these visual disturbances. Resolving the underlying condition of the vision loss will help, for example, cataract surgery for vision loss due to cataracts. Unfortunately, restoring vision is not usually possible. Reports indicate people have used eye movement, eye closure, or lighting changes at the time to dispel the hallucination. Reducing isolation, vision rehabilitation, and the use of optical aids can help an individual redirect visual stimulation.