Misconception 1


Back in 1760, Charles Bonnet referred to what his grandfather was experiencing in the more neutral term, visions. The more negatively toned, visual hallucinations, has become common place in contemporary medical parlance.

The problem with the term visual hallucination is that it is invariably linked to mental illness. Hence it is a term often feared by those people so affected. Research shows that those persons living with CBS tend to be reluctant to share their experiences lest they be viewed as 'crazy' or 'demented'.

Visual hallucinations refer to 'seeing' things that are not really there and yet believing that what one has 'seen' is indeed real. That is, the person incorporates such phantom imagery into their sense of reality. Typically, such visual hallucinations lead to delusions and consequently mental health problems such as psychosis.

CBS-affected people certainly experience imagery that is not really there however they typically have insight into the unreality of what they 'see'. The CBS-affected person understands what they 'see' is not - or cannot be - real, even though they keep 'seeing' the images. Therefore, CBS imagery is more correctly known as a pseudo-hallucination. This means that the images do not deceive the perceiver. And in turn does not indicate more widespread cognitive, memory or psychiatric decline. By and large, the CBS-affected person is of sound mind and memory.

The CBS Foundation believes that the use of the term visual hallucination is somewhat inappropriate and misleading. 'Seeing' phantom visions is hard enough for people with CBS but when their symptoms are couched in such medical/psychiatric terminology then it reinforces erroneous links to mental illness, dementia or senility. CBS is not a mental illness and the Foundation would prefer other terminology be used such as:                 

  • Visions            
  • Bonnet images
  • Involuntary images
  • Visual apparitions
  • Phantom images
  • Pseudo-hallucinations

Misconception 2


Increasing evidence is being compiled to show that the CBS landscape is far more varied than first thought. It is now being suggested that for about 35% of all those living with CBS, their experiences are unpleasant and generally have a negative impact upon the quality of their lives.

On top of this, many are finding that their CBS symptoms persist for much longer periods of time than traditionally thought. Once seen as a transient condition (ie. 12-18 months), it was recently discovered that 75% of those living with CBS had had their symptoms for at least five years (see Misconception 4). For such individuals, the standard information supplied about CBS (including reassurances that they are 'not going bonkers') may be insufficient to help them manage on a daily basis.

Misconception 3


Most published material claims that CBS images tend to bear no relationship to a person’s life experience. However, some certainly report imagery that appears to have direct relevance to their personal life. This includes:

  • An United Kingdom woman - but living in Australia for the past 25 years - 'sees' Union Jack waterfalls.
  • A car enthusiast who once drove vintage sports cars would primarily experience horizontal movement of images, typically vehicles.
  • A composer 'sees' musical notation superimposed on his walls.
  • A woman who worked with physically disfigured and abused children of war-torn Africa 40 years ago now 'sees' disfigured faces of dark skinned children.
  • A former builder's imagery includes housing estates and motorised equipment associated with the building industry.

These examples suggest that there may actually be a continuum of CBS experiences ranging from no (apparent) personal meaning to significant. Whether there are clinical repercussions for this remains a moot point. 

Misconception 4


For quite some time it was suggested that in approximately 60% of cases, symptoms resolved within 12-18 months. This somehow became generalised such that commentary on CBS often suggested 'not to overly worry, because CBS will typically end within 12-18 months.'  

However, in 2014, in the largest ever study of people living with CBS, it was found that in 75% of cases, CBS continued for five years or more (Cox & ffytche, 2014). This has further cast doubt on the standard view that CBS is just a transient condition. The Foundation's own anecdotal evidence suggests symptoms often last for several years and sometimes persisting for a decade or more.  

Misconception 5


Just as with dementia, CBS suffers from being labelled as a condition solely of the elderly. Whilst it is certainly the case that the majority of CBS cases occur in those of advancing years, it is important to stress that CBS can, and does, strike at any age.

There are several clinical reports of children as young as 6-7 years of age developing CBS as well as documented cases for those in early to mid adulthood. In fact, a recent research paper from Germany (Elflein et al, 2016) found that CBS occurs in younger populations of the vision-impaired (ie. under 40 yrs of age) with two subjects as young as 18 & 21. This study is one of the first to demonstrate that CBS is not restricted to those of advanced years.  

Misconception 6


The condition is only viewed as rare because of an entrenched mixture of silence, secrecy and (clinical) neglect. CBS is globally under-reported and under-recognised. This has repeatedly been the finding in published clinical papers from fields such as psychiatry, neurology and ophthalmology. 

People living with CBS tend to conceal their unusual visual experiences from others while clinicians are typically not screening for, or forewarning of, the syndrome. This unfortunate combination has managed to keep CBS relatively hidden.

Despite this, three separate studies by different vision-loss researchers (Gilmour et al, 2009; Cox & ffytche, 2014; O'Hare et al, 2015) have found estimated prevalence rates just shy of 40%. Further, in one paper, Menon (2005) found a prevalence rate of 63%. 

The largest ever global eye health study undertaken (Bourne et al, 2017) has forecast vision loss rates to treble by 2050 due to the growth and ageing of the world's population. In turn, this indicates CBS rates can also be expected to rise. The 'tip of the iceberg' proverb seems incredibly apt.

Misconception 7


Whilst some do find that closing the eyes relieves them of their symptoms, for many others their CBS images continue unabated. CBS images can definitely persist even with eyelids closed or being in darkness.  

Misconception 8


Whilst it is true that the bulk of CBS cases occur where a person has low visual acuity (eg. 6/38 - 6/120 or 20/125 - 20/400), there are cases where people develop CBS even though they have good to excellent visual acuity. Those living with both glaucoma and CBS can present with very good visual acuity. So too, CBS-affected people who have lost one eye (eg. enucleation) often have normal visual acuity in their remaining eye. 

Furthermore, we know that a sizeable proportion of people with low visual acuity do not develop CBS. This suggests that visual acuity in and of itself is not a determinant of CBS.

Misconception 9


There are innumerable forms of CBS imagery that can be encountered. Some imagery may be deemed 'pleasant' such as brightly coloured flowers or a mosaic but others can be viewed as:

  • 'irritating' (eg. green grid which constantly overlays one's visual field)
  • 'scary' (eg. distorted faces)
  • a neutral feeling (eg. a toaster). 

Even so-called pleasant CBS imagery can evoke unpleasant responses in the CBS-affected person:"Why am I seeing a waterfall when I'm sitting at the kitchen table?"

The person living with CBS can be quite perturbed by any form of imagery (regardless of its content) because they cannot account for why they are having such experiences. Understandably, their thoughts can turn to fearful scenarios of impending psychiatric disturbance or dementia. 

Misconception 10


This statement could not be further from the truth. What was once believed to be a fairly benign and transient condition, CBS is now becoming increasingly recognised as far more variable in its clinical profile than first thought. 

A far more gloomy profile - in terms of negative outcomes for those living with CBS - has emerged. It is now suggested that in ~35% of cases, the CBS symptoms are associated with anxiety, distress and reduced quality of life (Cox & ffytche, 2014). It was also found (same paper) that CBS continued for more than 5 years in 75% of cases. Further still, there is now some evidence that links CBS to higher mortality rates (Lapid et al, 2013) and CBS symptoms bear an uncanny similarity to conditions such as peduncular hallucinosis which makes clinical diagnosis tricky.

Clinical papers in a diverse range of academic disciplines over the past 35 years have repeatedly and consistently stated that CBS is terribly under-recognised by clinicians. In one study in the Netherlands it was found that for 16 CBS-affected individuals who consulted their GP or ophthalmologist, only one was correctly diagnosed (Tuenisse, 1996).  

Relatives of those affected by CBS often report having approached doctors and nurses about the condition only to be surprised and bemused that many were unfamiliar with the syndrome. The catch-cry that emanates over and over again is that CBS is under-reported, under-recognised and under-diagnosed.



Bourne, RA et al (2017). Magnitude, temporal trends, and projections of the global prevalence of blindness and distance and near vision impairment: a systematic review and meta-analysis. The Lancet (Global Health) Published online 02 August 2017. 

Cox, TM & ffytche, DH (2014). Negative outcome Charles Bonnet Syndrome. British Journal of Ophthalmology, 98: 1236-1239.

Elfein, H et al (2016). Charles Bonnet's syndrome: not only a condition of the elderly. Graefe's Archive for Clinical and Experimental Ophthalmology, 254(8): 1637-1642.

Lapid, MI et al (2013). Clinical phenomenology and mortality in Charles Bonnet Syndrome. Journal of Geriatric Psychiatry & Neurology, 26(1): 3-9.

Menon, GJ (2005). Complex Visual Hallucinations in the Visually Impaired. Archives of Ophthalmology, 123(3): 349-355.

O'Hare, F et al (2015). Charles Bonnet Syndrome in advanced retinitis pigmentosa. JAMA Ophthalmology, 122(9): 1951-3. 

Teunisse, RJ et al (1996). Visual hallucinations in psychologically normal people: Charles Bonnet syndrome. Lancet, 347: 794-7.