Misconceptions

10 MYTHS of CBS

Misconception 1

"CBS IS STRAIGHT FORWARD AND WELL-RECOGNISED BY CLINICIANS."

This statement - taken verbatim from a peak medical body representative - 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 outlook - 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 the syndrome continued for more than 5 years in 75% of cases. 

There is 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 can make clinical diagnosis tricky.

Clinical papers in a diverse range of academic disciplines over the past 40 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 et al, 1996). In a yet to be published study, a 56% CBS prevalence rate was found amongst a Leber's hereditary optic neuropathy (LHON) cohort and yet just a single subject had received a CBS diagnosis from a health professional (Kreimei et al, 2022). 

A Canadian study found that 55% of general practice doctors had never heard of Charles Bonnet syndrome (Gordon et al, 2018). An informal 2013 survey undertaken in Sydney, Australia found that less than 1% of GPs knew of the syndrome.

Relatives of those affected by CBS often report having approached doctors/nurses about the condition only to be surprised and bemused that many were unfamiliar with the syndrome. The reverberating catchcry is that CBS is seriously under-reported and sorely under-recognised. 

Misconception 2

"CBS IMAGES ARE VISUAL HALLUCINATIONS."

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.

There are two problems with the term visual hallucination. First, the phrase is invariably linked to mental illness. Hence it is a term often feared by those people so affected. Research and anecdotal evidence indicates that people living with CBS tend to be reluctant to share their experiences lest they be viewed as 'crazy' or 'demented'.

Second, visual hallucinations refers to seeing things that are not really there and yet believing that what one has 'seen' is actually real. This is known as a 'true' hallucination whereby the person incorporates such visual hallucinations into their sense of reality. This ultimately leads to mental health problems such as psychosis and delusions. 

CBS-affected people certainly experience imagery that is not really there however they typically have insight into the unreality of what they 'see'. The person living with CBS understands what they 'see' is not - or cannot be - real, even though the images can appear utterly lifelike. Therefore, CBS imagery is more correctly known as a pseudohallucination ('false' hallucination) or parahallucination (resembling an 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 person living with CBS is of sound mind.

The Foundation believes that the use of the term visual hallucination is somewhat inappropriate and misleading in relation to CBS. 'Seeing' phantom visions is hard enough for people living with CBS but when their symptoms are couched in psychiatric terms then it reinforces erroneous links to mental illness and neurodegenerative conditions such as dementia. Even the so-called correct terms - pseudohallucination or parahallucination - are quite unfriendly and evoke similar fears. 

CBS is not a mental illness and the Foundation would prefer less stigmatising language be used such as:                 

• Visual phantoms
• Bonnet images
• Phantom images      
• Visions

Misconception 3

"CBS IS A TEMPORARY AND BENIGN CONDITION. THE PRINCIPAL TREATMENT IS REASSURANCE."

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, sometimes terrifying, 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 discovered in 2014 that 75% of those living with CBS had had their symptoms for at least five years (see Misconception 5). 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 an ongoing basis.

Misconception 4

"CBS IMAGES HAVE NO PERSONAL MEANING."

Most published material claims that CBS images tends 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 has visions of 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 5

"CBS SYMPTOMS RESOLVE WITHIN 18 MONTHS."

This notion stubbornly persists. Family members ask why their loved one still has symptoms after 2 to 3 years. 

This whole idea - 'within 18 months' - stems largely from a single study in 1996, which undertook a 3 year follow up of CBS patients living with macular degeneration. From a sample of just ten patients, it was found that 6 noted their symptoms ended over a mean period of 18 months. This one-off finding somehow has become generalised across the board such that commentary often suggests 'CBS will typically end within 18 months'. 

However, 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 cast considerable doubt over the standard view that CBS is just a temporary condition. Further, the Foundation's own anecdotal evidence suggests that for the majority, symptoms last for several years and sometimes even persist for a decade or more. 

Even though it is true that some living with CBS do find that their visions resolve within a relatively short period of time, a more realistic picture needs to be painted: one that does not pin hopes on an early resolution of CBS. 

Misconception 6

"CBS IS AN OLDER PERSONS CONDITION."

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 5 years of age developing CBS as well as documented cases for those in early to mid adulthood. In fact, a 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 and 21. This study is one of the first to demonstrate that CBS is not restricted to those of advanced years.  

A nine year retrospective of CBS cases (under 25 years of age) within one eye hospital in London revealed 13 cases over that period (Jones & Moosajee, 2020). 

Misconception 7

"CBS IS A RARE CONDITION."

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 whilst clinicians are typically not screening for, or forewarning of, the syndrome. This unfortunate combination has managed to keep CBS relatively well-hidden. 

Despite this, four separate studies by different vision-loss researchers (Abbott et al, 2007; Gilmour et al, 2009; Cox & ffytche, 2014; O'Hare et al, 2015) have found estimated prevalence rates at, or just shy of, 40%. Further, Menon (2005) found a prevalence rate of 63%.

A Danish study (Subhi et al, 2022) has estimated that CBS affects 47.2 million worldwide. This may well be a conservative figure as their study only considered people over the age of 40 when it is known that CBS affects younger populations too. 

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 8

"CBS IMAGERY IS ONLY EXPERIENCED WITH OPEN EYES."

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. 

In the original 1758 dictated writings of Charles Lullin (Bonnet's grandfather) upon whom the syndrome is based, he mentioned that his visions occurred when his eyes were both open and shut.  

Misconception 9

"CBS ONLY OCCURS WITH LOW VISUAL ACUITY."

While 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.

There is also the misconception that only those who are deemed blind or 'legally blind' can develop CBS. This is not true. CBS also occurs in people with mild to moderate vision impairment. 

Misconception 10

"CBS IMAGERY IS ALWAYS PLEASANT."

Two separate studies have revealed identical results: 6% of those living with CBS found their experiences 'fairly pleasant' or 'positive' whereas a third (33%) reported negative reactions. 

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 or gargoyles)
• 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.

REFERENCES:

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.

Gilmour, G. & Ewing, C. (2009). An examination of the relationship between low vision and Charles Bonnet syndrome. Canadian Journal of Ophthalmology, 44(1), 49-52.

Gordon, K et al (2018). Family physician awareness of Charles Bonnet syndrome. Family Practice, 35(5), 595-598.

Jones, L. & Moosajee, M. (2020). Visual hallucinations and sight loss in children and young adults: a retrospective case series of Charles Bonnet syndrome. British Journal of Ophthalmology, 0: 1-6.

Kreimei, M. et al (2022). The incidence and characteristics of Charles Bonnet syndrome in Leber’s hereditary optic neuropathy in a large cohort. Acta Ophthalmologica, 100.

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. 

Subhi et al (2022). Prevalence of Charles Bonnet syndrome in low vision: a systematic review and meta-analysis. Annals of Eye Science; 7: 12.

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