THE ENIGMA BEHIND CHARLES
Netranee Anju Ramdinny-Purryag
Charles Bonnet Syndrome,
also known as visual release hallucinations, is the experience of complex
visual hallucinations in a person with partial or severe blindness. It was
first described by Charles Bonnet in 1760.1,2
Draaisma remarks, the ‘enormous variation in
the type of images’ seen by Charles Bonnet Syndrome patients is striking.3
Once regarded as
extremely rare, it is now known that up to 40% of people with impaired vision
develop Charles Bonnet Syndrome 4 although up to 60% may keep the
experiences to themselves.5
psychosis, delirium and early dementia is common5 and some people
with Charles Bonnet Syndrome have been almost confined to mental institutions.
So, clinicians need to remain vigilant for this intriguing condition.
Charles Lullin was a distinguished and well loved magistrate in Geneva for many years. He
was the grandfather of Charles Bonnet, who documented the experiences of the old
man when the latter was 89 years of age; the old man experienced visual
hallucinations. The elderly man was seeing things that were not there. He
developed a variety of hallucinations, ranging from simple to complex forms.
The simplest hallucinations he described were an infinity
of whirling atomic particles swirling around his field of view. He also had
hallucinations of simple lines and dots, coloured
blobs and geometrical patterns. He saw figures in his room, typically females
in elaborate flowing silk robes, but, bizarrely, wearing inverted tables or
caskets on their heads. In his room, the walls would become adorned with
paintings in beautiful golden frames, landscapes, portraits; things that he had
never seen before.6
Charles Lullin was normal sighted until about 80 years of age,
after which his vision began to deteriorate. At first this was partly
attributed to a cataract in one eye. In the late 80s’, Lullin’s vision deteriorated further and a second
cataract operation did not help. By the age of 89 years, he was unable to read
because he had lost his central vision, but with a preserved peripheral field.
In that state, he suddenly developed a variety of hallucinations, ranging from
simple to complex forms.6
In the 1930s, the
medical community decided to honour Charles Bonnet
with the naming of Charles Bonnet Syndrome to reflect that Bonnet had been the
first person ever to realize that visual hallucinations in eye disorders were
something rather different to the visual hallucinations encountered in mental
illness and Alzheimer’s disease.6
Explanations for this
psychoanalytical interpretation suggested that ‘the ego defends itself by
creating a substitute world full of entertaining scenes to compensate for the
visual loss.3 However, far from being entertained,
the hallucinations leave some people distressed.
A widely supported
theory suggests that the hallucinations are a mental equivalent of a phantom
limb.7 Half of the afferent neuronal fibres projecting to the brain begins in the eyes 8
and so, the brain expects a considerable perceptual input. According to the deafferentation theory, lack of stimuli to the visual
association areas of the cerebral cortex causes a release phenomenon similar to
phantom limb symptoms.7,9 As Draaisma
points out, the images often appear when vision begins to decline and then
disappear when blindness occurs. According to the release theory, the vision
should then be at their clearest when vision starts to decrease, as he notes.
offers another possible explanation. The hallucinations developed by sufferers
of Charles Bonnet Syndrome develop when some sufferers shut their eyes.10
In one study, 10 of 13 normally sighted patients report hallucinations while
being blindfolded for 5 days.7 This is however contradictory to Draaisma’s view that the images disappear when
Another theory proposes
a dysfunction in the brain’s censors. A psychoanalytic theory published
in 1962 suggested that the failing eyesight decreases the perception of
reality, which makes room for the products of imagination.3
version suggests that the brain’s censorship mechanism continually
removes irrelevant sensory impulses from conscious perception. However, this
depends on normal sensory input. If the input falls below a certain threshold, the brain allows subconscious
perceptions to surface producing visual hallucinations.10
There have been various prevalences reported for Charles Bonnet Syndrome. A 1989
review identified just 46 cases of Charles Bonnet Syndrome. More recent
prevalence estimates range from less than 1% to 40% of patients with impaired
vision. Several reasons account for this variation in prevalence: differences
in history taking, the definitions used and patients’ willingness to
report their hallucinations.7
Some definitions of
Charles Bonnet Syndrome do not include visual loss.7
do not agree whether certain images, for example bright lights and diffuse colours or auditory hallucinations are part of Charles
There is no specific
treatment for Charles Bonnet Syndrome.
Reassurance about the
nature of the illness, that is not being a mental illness, could be highly comforting
and all that may be needed.
and anticonvulsants have been used for Charles Bonnet Syndrome with good effect
in previous reports,11, 12 the
efficacy of these drugs in the treatment is somewhat questionable and should be
reserved for those who exhibit high levels of distress and have not responded
to conventional intervention.13
The treatment approach
would also depend on other comorbid physical or
mental disorders.13,14 Combination of medications and programmed
blinking or intermittent closing and opening of the eyes have been reported as
helpful.2 The techniques used in the treatment of Charles Bonnet
Syndrome are enumerated in the table which follows:
Techniques in the treatment of Charles Bonnet Syndrome
A change is made to see if hallucinations disappear.
For example, switch on a light to see if they disappear.
The eyes are moved from left to right every second
for up to 30 seconds without moving the head.
Staring at the image, blinking rapidly or reaching out
to touch the vision. For some, these methods help the vision to fade.
Moving around or performing a task, such as getting
up to make a cup of tea may help
Hallucinations may be worse when a person is
stressed out or tired. So, enough sleep is required to prevent hallucinations
The best solution is
however, finding the effective treatment to the eye disorder because Charles
Bonnet Syndrome has been reported to regress with effective treatment of the cause
of visual loss and improvement of visual activity.15,16
In conclusion, doctors
and relatives are advised to seek for hallucinatory experiences by asking the
visually impaired about it. Doing this would go a long way at ameliorating the
suffering of the usually impaired from this syndrome that could possibly be
passed off as a mental disorder. It would also strengthen the consultation
liaison services between psychiatry and ophthalmology.
.Morsier G. Le syndrome de
Charles Bonnet: Hallucinations visuelles des viellards sans deficience mentale (in French). Ann Med Psychol
Vukicevic M, Fitzmaurice K. Butterflies and black lacy patterns:
the prevalence and characteristics of Charles Bonnet hallucinations in an Australian
population. Clinical and Experimental Ophthalmology 2008; 36:659-65.
Draaisma D. Disturbances of the Mind. Cmbridge University Press 2009;11-39.
Singh A, Subhi Y, Sorensen
TL. Low awareness of Charles Bonnet Syndrome in patients attending a retinal clinic.
Danish Med J 2014; 61: A4770.
Jan T, Del Castillo J. Visual Hallucinations. Charles
Bonnet Syndrome. Western J Emerg Med 2012; 13: 544-7.
Dominique F. Charles Bonnet Synd.
MDS Digest 27-32.
Jackson ML, Ferencz J. Charles
Bonnet Syndrome: visual loss and hallucinations. Can Med Assoc J 2009;
Grunda T, Marsalek P, Sykorova P. Homonymous hemianopia
and related visual defects: Restoration of vision after a stroke. Acta Neurobiologiae Experimentalis 2013; 73: 237-49.
Singh A, Subhi Y, Sorensen
TL. Low awareness of the Charles Bonnet Syndrome- elderly people and visual
hallucinations. BMJ 2004; 328: 1552-4.
10. O’ Farrell L, Lewis S, Mckenzie
A, et al. Charles Bonnet Syndrome. A review of the literature. J Visual Impairment
Blindness 2010; 104: 261-72.
11. Terao T. Effects of Carbamazepine
and Clonazepam combination on Charles Bonnet
Syndrome. A case report. Hum Psychopharmacol Clin Exp 1998;13: 451-3.
12. Lang UE, Stokowski D, Schulze
D, Domula M, Schmidt E, Linat
JG, et al. Charles Bonnet Syndrome: Successful treatment of visual
hallucinations due to vision loss with SSRIs. J Psychopharmacol 2007; 21: 553-7.
13. Hartney KE, Catalano G, Catalano M.
Charles Bonnet Syndrome: Are medications necessary? J Psychiatr
Pract 2011; 17: 137-41.
14. Teunisse RJ, Cruysberg JR, Hoefnagels WH, Verbeek AL, Zitman FG. Visual hallucinations in psychologically normal
people: Charles Bonnet Syndrome. Lancet 1996; 347: 794-7.
15. Singh A, Sorensen TL. Charles Bonnet Syndrome improves
when treatment is effective in age related macular degeneration. British
Journal Ophthalmol 2011; 95: 291-2.
16. Meyer CH, Fleckensstein M, Rodrigues EB, Mennel S. Incidence
and regression of Charles Bonnet Syndrome in vascular age-related macular
degeneration. British Journal Ophthalmol 2011; 95: