CBS Defined

A vision-impaired
person of sound mind experiences
phantom images (visions) in
their visual field.

National helpline
1300 121 123


The Mystery

There are many layers of mystery to this syndrome:

  • Back in 1760, Bonnet correctly surmised that an 'organ of sight' in the brain was responsible for the phantom visions. Modern neuroscience appears to confirm his thoughts. However, precisely how and why CBS occurs remains unexplained.  


  • Another part of the mystery is the actual content of people's visions. One might expect that the visual imagery of CBS would be of a basic form. But actually, often the forms are remarkably intricate or unusual. For example, when figures are involved, rather than appearing to be rather straight forward, the characters can often have peculiar aspects to them such as having a distorted face, being adorned in exotic headdress or wearing long, flowing robes from ancient times. Some encounter scenes of marching soldiers who are miniature in size or a human being who is as tall as a horse. A few even find themselves in a completely different environment to where they actually are: for example, being at home in Australia during summer but it seems you're surrounded by a Polish winter landscape. Seeing anything that is not truly there is extraordinary enough but the fact that many report qualities that are well beyond the standard only adds to the syndrome's mystique. 


  • A puzzling dimension is that medical and health care practitioners of today are often not aware of the syndrome. Meanwhile, the people who are actually living with the condition tend to keep their visual experiences a closely guarded secret. This unfortunate overlap has ensured silence and mystery prevails.



CBS seems to remain a blind spot for medical practitioners and health care professionals. One study reported that of 16 CBS-affected persons who consulted either their general practitioner (GP) or eye specialist, only one was given the correct diagnosis (Teunisse et al, 1996).

In an informal 2010 survey of 343 GPs in the Sydney metropolitan area, only two reported that they had heard of Charles Bonnet syndrome (0.56%). These two GPs admitted their knowledge of CBS was scant.

Further, a recent study of GP awareness of CBS in Canada found that 55% of GPs were 'not at all aware' of Bonnet syndrome (Gordon & Felfeli, 2018). The paper also remarked:

"Almost all respondents [GPs] never discussed Charles Bonnet syndrome as a possibility with patients who have experienced severe vision loss."  (p.3)


Client / patient

What further compounds the mystery is that somewhere between 40 - 65% of CBS-affected persons tend to not mention their symptoms to anyone. This includes a spouse or family member. It seems that the fear of:

  • being labelled 'crazy',
  • 'losing one's independence', 
  • 'worrying a loved one' or
  • 'not being taken seriously' are reasons that inhibit people talking about their CBS experiences.

With CBS-affected individuals generally not sharing their unusual visual experiences (for understandable reasons), it has further contributed to the condition remaining incredibly well-hidden. 


Mystery overview

  • The actual cause of CBS remains essentially unknown. 
  • Why some people with vision loss develop the syndrome while others do not remains unsolved.
  • Safe, reliably effective treatment for CBS is yet to be found.
  • Modern neuroscience cannot yet explain how or why Bonnet images occur.
  • It remains baffling how the CBS images often possess stunning detail combined with curiously odd aspects. 
  • Knowledge of CBS within the general community is virtually non-existent. 
  • Awareness of CBS within the medical and health care sectors is seemingly low.
  • What is known about CBS continues to poorly filter down to clinical settings and to the wider community.




Teunisse, R. et al (1996). Visual hallucinations in psychologically normal people: Charles Bonnet's syndrome. The Lancet, 347, 794-798.

Gordon, K., Felfeli, T. (2018). Family physician awareness of Charles Bonnet syndrome. Family Practice, 1-4.