Visual hallucinations in low vision patients

Behrouz Maleki BSc of OptometryMSc & PhD student of Psychology

Charles Bonnet's syndrome

05/03/2023

Visual hallucinations in psychologically normal people who have lost vision

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Definitions

Illusion misinterpreting real objects

Hallucinationperception of an external object when no such object is present

Delusionbeing convinced that what the perceived hallucinations are real

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History

In about 1760, Charles Bonnet, a Swiss naturalist and philosopher, described the vivid hallucinations experienced by his 87-year-old grandfather.

In 1936 de Morsier (whom, like Charles Bonnet, was a native of Geneva Switzerland), named the phenomenon after Charles Bonnet.

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Importance• CBS is not a well known condition, but is a common one. (at least

10%-15% of patients with visual loss are affected)

• Unfortunately some health professionals are not aware it.

• CBS occurs frequently in elderly, visually handicapped patients.

• People live longer

• According to UN reports world’s population is aging rapidly

(median age of Iranians have raised to 27 years in 2010, up from

21 years in 2000. The median age could reach 40 years by 2030.)

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Epidemiology

• Considerable under-reporting• 10%-15% of patients with moderate visual loss• Up to 50% of people with severe visual loss

• Can affect the young as well as the old• But most patients are elderly (mean age: 70 to 85 years)

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Complications

• Hallucinations may interfere with daily life and negatively impact quality of life

•Anger

•Worry that the hallucinations are caused by mental illness, Anxiety

• Depression and social isolation

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Nature of Hallucinations• Occur in a “state of quiet restfulness”

• Start without warning, last for a few minutes or for several hours

• Are very detailed, and much clearer than patient’s current vision

• Interact and conform to actual surroundings

• Make eye contact with the viewer

• Always outside the body

• Patient knows they are not real

• Have no personal meaning to the patient

• Are pleasant expressions

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Nature of Hallucinations• Simple repeating patterns:

patterns, dots, shapes or lines which can form into more complicated patterns such as brickwork, network of branches, mosaic or tiles or seeing different patterns on people’s clothing.(clear description of the shape or position of the image)

• Complex hallucinations:

hallucinations of people, animals, objects, texts or letters, moving vehicles and landscapes.

• Both types of hallucination may occur simultaneously or subsequently

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Nature of Hallucinations

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Causes

Risk factors include:

• vision impairment (especially from ARMD)• old age• hearing impairment• living alone• very little social interaction

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Causesloss of vision from an eye condition:

• Age-related macular degeneration (ARMD)• Cataract• Glaucoma• Diabetic retinopathy and other Retinal disorders with vision loss• Choroidal neovascularization• Visual field defects following stroke or neurosurgery• Bilateral optic nerve damage due to methyl alcohol poisoning• Vision loss from retinopathy of prematurity (ROP)

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Pathogenesis

Sensory deprivation (deafferentation) theory:

3

2

1 Ocular lesion

Reduced sensory input to the brain

Visual brain struggles to make sense of the fragments it has seen

4 Displaying images which are stored or self produced

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Pathogenesis

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Pathogenesis

Sensory deprivation (deafferentation) theory:

• After a time, the visual brain readjusts to its new level of stimulation from the eye and the spontaneous firing of cerebral neurons diminishes.

• 13 normally sighted patients • were blindfolded for 5 days• 10 of these patients reported hallucinations after an average of 1 day

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DiagnosisMain diagnostic criteria:

Visual Loss: • Any type or degree of visual loss• Poor vision in both eyes• Occurs around the time of vision loss

Recurrent Visual hallucinations: • At least one hallucination within the past month• Period between the first and the last hallucination must exceed one month• No hallucinations in other senses

Insight: • Normal cognitive status• Full or partial Insight into the unreal nature of the hallucinations• No delusions

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Differential diagnosisSimple hallucinations:• Ocular disease (e.g. retinal detachment)• Neuro-ophthalmic disease (e.g. optic neuritis)• Neurological disease (e.g. migraine, occipital lobe tumors)

Complex hallucinations:Psychiatric diseases and neurologic diseases:• Drug-intoxication states and drug-withdrawal states• Adverse effect of medication• Schizophrenia and other psychotic mental illness• Delirium• Dementia• Alzheimer's disease (AD)• Parkinson disease• Strokes and other brain conditions, which affect visual brain

Patients with difficulty with mentation, poor insight, numbness, tingling, weakness on one side of the body other neurologic or systemic signs or symptoms should be referred for psychiatric or neurologic evaluation

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Prognosis

The saying "This, too, shall pass" is almost true for those with CBS.For many, the symptoms subside after about 18 months

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Professionals and CBS

• Every health care practitioner should be educated about CBS.

• The eye care professional is the best healthcare professional to diagnose this condition

• It is advised to discuss CBS with any patient whose visual acuity is 20/100 or 20/200 in both or the better eye

• CBS patients should be encouraged to talk about their hallucinations

• The professionals in the mental health field are the experts at helping people deal with hallucinations, depression or anxiety

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ManagementForewarning and education• Forewarning the possibility of hallucinations helps patients cope as they occur• Nature of these hallucinations

Empathy and reassurance• It is a functional problem with their sight, not a problem with their mind• It is a normal occurrence in many visually-impaired people (Normalizing)• The condition usually improves with time

Practical changes to lifestyle and Home modification• Improving vision by improving lighting or the use of optical devices• Physical condition (e.g. not smoking and avoiding sun exposure to the eyes)• Getting enough rest and having enough sleep• Reducing causes of and increasing coping skills around stress• Find ways to reduce social isolation and lack of stimulation

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Cop with hallucinationsIs this too detailed to be real?Having a good knowledge of your surroundings

Distracting the brain• Having the TV or radio on• moving around a little• standing up• Walk away from the hallucination or reaching out towards it• Closing and opening your eyes, blinking and eye exercises• Staring at or fixating on the image• Holding breath• Even feeling a dice with dimples

Pharmaceutical treatment should only be considered in patients:• Experiencing distressing hallucinations • Cannot tolerate these despite non-pharmaceutical approaches

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Thank You!With special thanks to KOA