Charles Bonnet Syndrome 101

The Charles Bonnet Syndrome is a neurological syndrome that causes visual hallucinations. Damage to the anterior or posterior visual pathway causes the hallucinations, which the patient does not perceive as real. If eyesight can be improved through glasses or surgery, symptoms can go away completely.

What is Charles Bonnet Syndrome?

Charles Bonnet syndrome is a complex of neurological psychiatric symptoms. At first glance, the symptoms resemble those of mentally ill people. In the real sense, however, those affected are not mentally ill, but neurologically damaged. The main symptom for the syndrome is visual hallucinations. The hallucinations are even limited to the visual system. There are no acoustic or tactile phenomena.

Also a delusion not develop patient of Charles Bonnet syndrome usually. You perceive the complex and sometimes moving hallucinations for several minutes with unclouded consciousness before they subside again. The natural scientist Charles Bonnet first described the syndrome. The phenomenon mainly affects the elderly. Corresponding cases have also been observed in children.


Meanwhile, medicine suspects damage to the visual pathways and the slow loss of vision behind the CB syndrome. Hallucinations can both be caused by damage to the front part and damage to the rear part of the visual pathways. For this reason, the syndrome can occur, for example, in the context of diseases such as macular degeneration, diabetic retinopathy or cataracts, which especially older people are often affected by.

Also cerebral infarcts or brain tumors occur as the primary causes of the question. Hallucinations take place especially in the blind area of ​​the field of vision. Therefore, medicine suspects a connection to the association cortex, which is tied to the visual system. If not only the visual pathways are damaged, but also the cortex of the visual hallucinations, hallucinations cannot occur. In the case of most defects in the visual pathways, the cortex is preserved, as is the visual imagination.

Symptoms, ailments & signs

The main symptom of the CB syndrome are visual hallucinations that occur without previous psychological illnesses with a completely clear consciousness and are not accompanied by hallucinations from other perceptual systems. These hallucinations are stereotypical optical hallucinations that the patient experiences from a distance. He doubts the authenticity of the pictures.

There is therefore no delusional experience with actual involvement in the hallucinatory world. The images can therefore actually not be described as hallucinations, but rather as illusions and pseudo-hallucinations.

If there is a implication, a mental illness is the more likely cause and the clinical picture can no longer be summarized as CB syndrome. Typically, the illusions in the CB syndrome correspond to light phenomena, geometrical figures with clear outlines, distortions of objects or fantasy figures just seen and double hallucinations.

Diagnosis & course

Charles Bonnet syndrome has to be differentiated from diseases such as Lewy body dementia, hallucinatory migraine attacks, the side effects of certain drugs and the effects of hallucinogenic drugs. When making a diagnosis, in addition to the anamnesis, an inspection of the visual pathways can provide crucial information.

As a rule, however, the causal damage to the visual pathway is diagnosed well before the first hallucinations. Therefore, the medical history is usually sufficient to make a diagnosis of CB syndrome. Up to almost 60 percent of all people with impaired visual acuity are said to suffer from Charles Bonnet syndrome. The prognosis depends in each individual case on the possibilities of improving eyesight. Although the syndrome is a harmless disease in and of itself, it can affect patients’ quality of life.

When should you go to the doctor?

In the case of Charles Bonnet syndrome, a doctor should then be seen if the person is suffering from hallucinations. As a rule, however, the patient can determine for himself that the hallucinations are not real and differentiate them from reality. The doctor should especially be seen if these symptoms occur after an accident or after a blow to the head. Severe migraines and other head pain can also indicate Charles Bonnet syndrome and should be investigated.

In many cases the patient sees in his hallucinations a doppelganger or different light phenomena, the authenticity of which he questions, however. Decreased eyesight is also a sign of Charles Bonnet Syndrome and should definitely be examined. Diagnosis and treatment can be carried out by a psychologist. Eye discomfort can usually be improved by surgery or by wearing glasses. It cannot be universally predicted whether the disease will progress positively.

Treatment & Therapy

Medicinal substances such as the antipsychotics melperon and risperidone, anticonvulsants such as carbamazepine and clonazepam or serotonin antagonists such as ondansetron are available to alleviate the symptoms. However, this symptomatic treatment is rarely carried out. In connection with drug therapies, the benefits and risks for the patient are first weighed up. Since the CB syndrome is not threatening in and of itself, the doctor can, for example, advise against taking medication from the outset.

Since a causal therapy is available for the CB syndrome, this therapy usually corresponds to the primary treatment. The attending physician strives to improve eyesight. Instead of medication, glasses or operations are usually used. A lens operation can completely reduce the visual hallucinations in some diseases. If the symptoms of the syndrome are confined to the dark, adequate lighting is often sufficient to mitigate the hallucinations.

In some cases, the causal therapy does not make the hallucinations go away completely. As a rule, however, the intensity is reduced. Supportive therapy can also be appropriate to accompany the causal treatment. The patient’s suffering is relieved and the quality of life increases. Since socially isolated people suffer from CB syndrome all the more often, supportive therapy with social ties can even aim to improve symptoms. At least those affected have the opportunity to talk to each other about their suffering in institutions such as self-help groups.

Outlook & forecast

As a rule, a general prognosis cannot be given for Charles Bonnet syndrome. The further course depends on the exact cause of the syndrome and its severity.

If the sufferer’s eyesight can be improved, the symptoms of Charles Bonnet Syndrome can in most cases be completely overcome. The eyesight is mainly improved by interventions with a laser or by wearing glasses. In these cases, the disease progresses positively without complications.

Since the symptoms of the syndrome often only appear in the dark, they can be alleviated by suitable lighting so that there are no particular restrictions in the everyday life of the person concerned. Because the person concerned does not experience the hallucinations as real, they can often go about an ordinary life even if the condition cannot be completely alleviated.

The treatment of Charles Bonnet Syndrome with the help of medication only very rarely leads to success, so that it is usually not used. The syndrome does not have a negative impact on the life expectancy of the person affected. The further course depends strongly on the underlying disease.


In many cases, Charles Bonnet Syndrome can be prevented by providing adequate visual aids.


Follow-up care for Charles Bonnet Syndrome usually begins after therapy with psychotropic drugs or after lens surgery. Often glasses are used, which are supposed to improve eyesight. Depending on when the syndrome primarily occurs, it may be helpful to adjust the lighting. But there are also cases in which the hallucinations persist.

At least they can be reduced with bright light. As a support and aftercare, this solution for increasing the quality of life is quite simple. Often the affected patients are relatively isolated people. This is why follow-up therapy with a stronger social connection is helpful. The symptoms no longer occur as often and as severely.

This aftercare includes, for example, participating in a self-help group. Here the patients feel less alone and can exchange ideas about possible methods of alleviating their visual problems. In such a self-help group or at the doctor’s office, they learn that the problem is a physical defect and not a special form of mental illness. The drugs that the doctor prescribes are usually not completely successful, but with the right approach, patients have no problems coping with everyday life.

You can do that yourself

In order to cope better with the disease in everyday life, it is important for the patient and, above all, his social environment to internalize that Charles Bonnet syndrome is not a mental illness. Those affected are not mentally ill, but suffer from a purely physical defect.

In self-help groups that are active on the Internet and in larger cities, those affected learn to cope better with their hallucinations and the often discriminatory or even humiliating reactions of the social environment. These groups also provide information material that can be used to educate the near-social field, especially employers and work colleagues, about the disease. In this way, prejudices resulting from ignorance can be broken down.

In addition, those affected should seek professional medical care. Charles Bonnet Syndrome is a rather rare disease. It is therefore important that the person concerned seeks a specialist who is already experienced in treating the syndrome. Information on appropriately qualified doctors is available from the medical associations and health insurance companies.

The causes of the disease have not yet been conclusively clarified, but treatment successes are already being achieved. A person affected should therefore be fully informed about all medical possibilities to alleviate their suffering.

Charles Bonnet Syndrome

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