Visual release hallucinations

Visual release hallucinations, also known as Charles Bonnet syndrome or CBS, are a type of psychophysical visual disturbance and the experience of complex visual hallucinations in a person with partial or severe blindness.

First described by Charles Bonnet in 1760,<ref>,

 Le syndrome de Charles Bonnet: hallucinations visuelles des vieillards sans deficience mentale, 
 Ann. Méd.-Psychol., 
 1967,
 Vol. 125,
 pp. 677–701,</ref><ref name="Vukicevic/Fitzmaurice">, 
 Butterflies and black lacy patterns: The prevalence and characteristics of Charles Bonnet hallucinations in an Australian population, 
 Clinical & Experimental Ophthalmology, 
 2008,
 Vol. 36(Issue: 7),
 pp. 659–65,
 DOI: 10.1111/j.1442-9071.2008.01814.x,
 PMID: 18983551,</ref> the term Charles Bonnet syndrome was first introduced into English-speaking psychiatry in 1982.<ref>, 
 The Charles Bonnet Syndrome and the Problem of Visual Perceptual Disorders in the Elderly, 
 Age and Ageing, 
 1982,
 Vol. 11(Issue: 1),
 pp. 17–23,
 DOI: 10.1093/ageing/11.1.17,
 PMID: 7041567,</ref>  A related type of hallucination that also occurs with lack of visual input is the closed-eye hallucination.

Signs and symptoms

People with significant vision loss may have vivid recurrent visual hallucinations (fictive visual percepts).<ref name=":1" /> One characteristic of these hallucinations is that they usually are "lilliputian" (hallucinations in which the characters or objects are smaller than normal).<ref>Vojniković, Bozo,

 What associates Charles Bonnet syndrome with age-related macular degeneration?, 
 Collegium Antropologicum, 
 
 Vol. 34 Suppl 2,
 pp. 45–48,
 
 PMID: 21305724,
 
 
 Full text,</ref> Depending on the content, visual hallucinations can be classified as either simple or complex.<ref name=":1" /> Simple visual hallucinations are commonly characterized by shapes, photopsias and grid-like patterns.<ref name=":0">Pang, Linda, 
 Hallucinations Experienced by Visually Impaired: Charles Bonnet Syndrome, 
 Optometry and Vision Science, 
 
 Vol. 93(Issue: 12),
 pp. 1466–1478,
 DOI: 10.1097/OPX.0000000000000959,
 
 PMC: 5131689,
 
 Full text,</ref> On the other hand, complex visual hallucinations consist of highly detailed representations of people and objects.<ref name=":0" /> The most common hallucination is of faces or cartoons.<ref name="ted">

TED2009. Oliver Sacks: What hallucination reveals about our minds | Video on(link). {{{website}}}. Ted.com.

</ref> Sufferers understand that the hallucinations are not real, and the hallucinations are only visual, that is, they do not occur in any other senses, e.g. hearing, smell or taste.<ref>,

 The Charles Bonnet syndrome: 'phantom visual images', 
 Perception, 
 1991,
 Vol. 20(Issue: 6),
 pp. 809–25,
 DOI: 10.1068/p200809,
 PMID: 1816537,</ref><ref name="Mogk/Riddering/Dahl/Bruce/Brafford">, 
  
 Vision Rehabilitation, 
  
  
 2000, 
  
  
 ISBN 978-90-265-1631-3, 
  
  
  
 Pages: 117–9,</ref> Visual hallucinations generally appear when the eyes are open, fading once the visual gaze shifts.<ref name=":1" /> It is widely claimed that sensory deprivation is instrumental in the progression of CBS.<ref name=":2" /> During episodes of inactivity, hallucinations are more likely to occur.<ref name=":1" /> Majority of those suffering from CBS describe the duration of hallucinations to continue for up to a few minutes, multiple times a day or week.<ref name=":1" />

Even though people of all ages may be impacted by Charles Bonnet Syndrome, those within the age range of 70 to 80 are primarily affected.<ref name=":1" /> Among older adults (> 65 years) with significant vision loss, the prevalence of Charles Bonnet syndrome has been reported to be between 10% and 40%; a 2008 Australian study found the prevalence to be 17.5%.<ref name="Vukicevic/Fitzmaurice" /> Two Asian studies, however, report a much lower prevalence.<ref>,

 Charles Bonnet syndrome in Asian patients in a tertiary ophthalmic centre, 
 British Journal of Ophthalmology, 
 2004,
 Vol. 88(Issue: 10),
 pp. 1325–9,
 DOI: 10.1136/bjo.2004.041947,
 PMID: 15377560,
 PMC: 1772345,</ref><ref>, 
 Visual Loss and Visual Hallucinations in Patients with Age-Related Macular Degeneration (Charles Bonnet Syndrome), 
 Investigative Ophthalmology & Visual Science, 
 2007,
 Vol. 48(Issue: 3),
 pp. 1416–23,
 DOI: 10.1167/iovs.06-0942,
 PMID: 17325191,</ref> The high incidence of underreporting this disorder is the greatest hindrance to determining the exact prevalence.<ref name="Mogk/Riddering/Dahl/Bruce/Brafford" /> Underreporting is thought to be a result of sufferers being afraid to discuss the symptoms out of fear that they will be labeled of unsound mind.<ref name="Mogk/Riddering/Dahl/Bruce/Brafford" />

Pathophysiology

File:Lawrence 1960 9.7.png

Anatomical illustration of human neuroanatomy

There is no general consensus on the definition of CBS.<ref name=":0" /> Predominant factors correlated with CBS are a decrease of visual acuity, visual field loss, and elderly age.<ref name=":1" /> While characteristic features of visual hallucinations are not specifically linked to the anatomical site of the ocular injury, they usually match to the location of visual loss.<ref name=":1" /> The most commonly accepted theory for Charles Bonnet Syndrome proposes that extreme visual impairment promotes sensory deafferentation, leading to disinhibition, thus resulting in sudden neural firings of the visual cortical regions.<ref name=":1" /> A few studies record that visual hallucinations are likely to be concentrated in the blind regions.<ref name=":2"> Reichert, David P.. Hallucinations in Charles Bonnet Syndrome Induced by Homeostasis: a Deep Boltzmann Machine Model(link). NIPS Proceedings.

</ref> Functional magnetic resonance imaging (fMRI) of Charles Bonnet Syndrome patients display a relationship between visual hallucinations and activity in the ventral occipital lobe.<ref name=":1" /> A connection between age-related macular degeneration (AMD) and colored visual hallucinations has been presented.<ref name=":0" /> Color vision signals travel through the parvocellular layers of the lateral geniculate nucleus (LGN), later transmitting down the color regions of the ventral visual pathway.<ref name=":0" /> Due to cone photoreceptor damage located in the macula, there is a significant reduction of visual input to the visual association cortex, stirring endogenous activation in the color areas and thus leading to colored hallucinations.<ref name=":0" /> Patients with CBS alongside macular degeneration exhibit hyperactivity in the color areas of the visual association cortex (as shown in fMRI’s).<ref name=":0" /> Those with significant ocular disease yet maintain visual acuity may still be susceptible to CBS.<ref name=":0" />

The Deep Boltzmann Machine (DBM) is a way of utilizing an undirected probabilistic process in a neural framework.<ref name=":2" /> Researchers argue that the DBM has the ability to model features of cortical learning, perception, and the visual cortex (the locus of visual hallucinations).<ref name=":2" /> Compelling evidence details the role homeostatic operations in the cortex play in regards to stabilizing neuronal activity.<ref name=":2" /> By using the DBM, researchers show that when sensory input is absent, neuron excitability is influenced, thus potentially triggering complex hallucinations.<ref name=":2" />

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Acetylcholine Pathway

A short-term change in the levels of feedforward and feedback flows of information may intensely affect the presence of hallucinations.<ref name=":2" /> In periods of drowsiness, CBS related hallucinations are more prone to arise.<ref name=":2" /> Disrupting cortical homeostatic processes after vision has been lost may prevent or setback the emergence of hallucinations.<ref name=":2" /> At varying stages of the cortical grading, acetylcholine (ACh) may impact the balance of thalamic and intracortical inputs as well as the balance in between bottom-up and top-down.<ref name=":2" /> Particularly in CBS, a shortage of acetylcholine at cortical locations should correspond to the onset of hallucinations.<ref name=":2" />

The syndrome can also develop after bilateral optic nerve damage due to methyl alcohol poisoning.<ref>,

 Optical hallucinations in the aged with diseases of the eye, 
 Zeitschrift für Gerontologie, 
 1987,
 Vol. 20(Issue: 4),
 pp. 227–9,
 
 PMID: 3660920,</ref>

Diagnosis

A variety of disciplines including optometry, ophthalmology, geriatric medicine, psychiatry, and neurology play a part in securing the diagnosis of CBS.<ref name=":0" /> Since CBS is not commonly recognized by all clinicians, it oftentimes goes misdiagnosed and identified as psychosis, delirium, or dementia.<ref name=":1" /> As a result of this, it is estimated that almost 60% of CBS patients hesitate to notify their physicians.<ref name=":1" /> By focusing on the specific type of visual hallucination, one may find an accurate diagnosis.<ref name=":1" /> If a patient presents symptoms indicative of Charles Bonnet Syndrome, basic laboratory examinations like metabolic panel and blood count tests, as well as neuroimaging, may aid in an accurate diagnosis.<ref name=":1" />

Prognosis

There is no treatment of proven effectiveness for CBS.<ref name=":0" /> For those experiencing CBS, knowing that they are suffering from this syndrome and not a mental illness seems to be the most comforting treatment so far, as it improves their ability to cope with the hallucinations.<ref name=":0" /> As time passes from the initial onset of visual hallucinations, studies show that around 60% of those living with CBS feel that visual hallucinations have no effect on their lives, 33% of people feel that the hallucinations are disruptive to their lives, and 7% of people even find pleasure in the hallucinations.<ref name=":0" />

A large proportion of those suffering from CBS develop the visual hallucinations as vision begins to deteriorate and stop hallucinating once vision is entirely gone.<ref name=":2" /> Complex hallucinations may progress over time if the primary loss of vision is due to damage of the early cortical areas.<ref name=":2" /> If activation of the early cortical areas is suppressed when CBS symptoms have already been exhibited, hallucinations may temporarily terminate.<ref name=":2" /> Also, interrupting vision for a short time by closing the eyes or blinking may be helpful.<ref name="Vukicevic/Fitzmaurice" />

It is possible for a stressful life event to alter the disposition of hallucinatory experiences as well as the emotional experiences (from unconcerning to concerning) in CBS.<ref name=":3">Vukicevic, Meri,

 Frightening visual hallucinations: atypical presentation of Charles Bonnet syndrome triggered by the Black Saturday bushfires, 
 The Medical Journal of Australia, 
 
 Vol. 193(Issue: 3),
 pp. 181–182,
 DOI: 10.5694/j.1326-5377.2010.tb03843.x,
 
 
 
 Full text,</ref> As expressed in some patients, an interplay between CBS and an acute or post-traumatic stress disorder may exist.<ref name=":3" /> The role that trauma plays in CBS may affect how and when a hallucinatory episode is triggered.<ref name=":3" />

History

File:CharlesBonnet.jpg

Charles Bonnet, the first person to describe the syndrome.

The disease was first noted by the Swiss naturalist Charles Bonnet, who described the condition in 1760.<ref name=":1" /> He documented it in his 89-year-old grandfather<ref>Bonnet Charles (1760) Essai Analytique sur les facultés de l’âme. Copenhagen: Philibert, pp 426–428</ref> who was nearly blind from cataracts in both eyes.<ref name="ted" /> After Bonnet’s grandfather received bilateral cataract surgery, his vision evolved from slightly better to complete deterioration over time.<ref name=":0" /> It was around this period that his visual hallucinations started.<ref name=":0" /> His hallucinations consisted of perceptions of men, women, birds, carriages, buildings, tapestries, physically impossible circumstances and scaffolding patterns.<ref name="ted" /><ref>

Bonnet's syndrome (Charles Bonnet)(link). {{{website}}}. Whonamedit.

</ref> Even though his health was in good shape and he had an absence of any psychiatric disorders, the source of the hallucinations remained unknown.<ref name=":0" /> At forty years old, Charles Bonnet himself suffered from an unrevealed cause of severe vision loss.<ref name=":0" />

In 1967, French-Swiss neurologist, Georges de Morsier, coined the term Charles Bonnet Syndrome in Bonnet's honor.<ref name=":1">Jan, Tiffany,

 Visual Hallucinations: Charles Bonnet Syndrome, 
 Western Journal of Emergency Medicine, 
 
 Vol. 13(Issue: 6),
 pp. 544–547,
 DOI: 10.5811/westjem.2012.7.12891,
 PMID: 23357937,
 PMC: 3555593,
 
 Full text,</ref> De Morsier’s description of CBS implies a concentrated neurodegeneration, usually occurring in the elderly with typical cognition.<ref name=":0" /> In 1936, well-renowned neuropsychiatrists, Jean Lhermitte and Julian de Ajuriaguerra, concluded that visual hallucinations comprise of thalamic lesions as well as ocular pathology.<ref name=":0" /> This definition contradicted De Morsier’s, as he believed there was no ocular pathology involvement in hallucinations.<ref name=":0" /> In psychiatric literature, the most commonly accepted interpretation of CBS is that of Gold and Rabins’.<ref name=":0" /> In 1989, they detailed that the hallucinations associated with CBS are not affecting other sensory modalities.<ref name=":0" /> They believed that the visual hallucinations are oftentimes stereotyped, persistent, and/or repetitive in nature.<ref name=":0" /> 

Society and culture

The syndrome is discussed in

• Vilayanur S. Ramachandran's book Phantoms in the Brain. Ramachandran suggests that James Thurber, who was blinded in one eye as a child, may have derived his extraordinary imagination from the syndrome.<ref>{{{last}}},

 V.S. Ramachandran, 
  
 Phantoms in the Brain, 
  
 HarperCollins, 
 1988, 
  
  
  
  
  
  
 Pages: 85–7,</ref>

• Vikram Chandra's book Sacred Games (2006)
• David Eagleman's book Incognito: The Secret Lives of the Brain
• Oliver Sacks' 2012 book Hallucinations
• The Indian movie Jawan of Vellimala released in 2012, where Mammootty is a victim of this disease.<ref name=moviebase>

Movie Review: Jawan of Vellimala(link). {{{website}}}. NowRunning.

</ref>

• "The Black Canvas" (2014), a chamber opera by the Greek composer Spyros Syrmos, is about a celebrated painter whose visions are caused by CBS.
• Margaret Atwood's short story "Torching the Dusties"
• Deborah Lawrenson's novel "The Lantern" (2011)
• Gareth Brookes' graphic novel A Thousand Coloured Castles (2017)
• The 2019 Netflix film Velvet Buzzsaw
• Dealt, 2017 documentary about notable victim Richard Turner