What Is Meant By Visual hallucinations?
Visual hallucinations are defined as the perception of an external object when no such object is present.
Classification of Visual hallucinations
Visual hallucinations can be classified as
1. Simple or
2. Complex.
1. Simple visual hallucinations type includes photopsia, lines or patterns which can be seen in ocular diseases like posterior vitreous detachment, optic neuritis, migraine or occipital lobe seizures or tumours.
2. Complex visual hallucinations are usually well formed images and relatively stereotyped and involve humans animals and figures in bright colours. The aetiologies vary and include delirium tremens, dementias, Parkinson’s disease, complex partial seizures, drug abuse etc.
The images may disturb the patient and the patient may lose mental balance.
Charles Bonnet syndrome
Charles Bonnet syndrome is a disorder in which affected individuals present with complex visual hallucinations and visual loss. It was first described by Charles Bonnet, a naturalist and philosopher in 1760.
First Case Of Charles Bonnet syndrome
Charles Bonnet described this condition in his grandfather who was otherwise cognitively unimpaired, had blindness due to cataract and suffered complex visual hallucinations.
In Which other Conditions Charles Bonnet syndrome has been described?
It has been described in several ophthalmic conditions associated with vision loss such as age related macular degeneration, diabetic retinopathy, glaucoma and cataract. The condition is attributed to a cortical release phenomenon due to lack of visual input much like the phantom limb phenomenon.
Prevalence Of Charles Bonnet syndrome
Its prevalence in patients with visual loss varies from 0.4% to 15%. Actual prevalence may be more because certain cases are not detected due to –
1. Some people do not report the symptoms for fear of being labeled as mentally unwell or demented.
2. Doctors are also unfamiliar with the syndrome as a possible diagnosis
Since visual hallucinations are associated with a wide variety of conditions affecting visual pathway as well as other brain structures, systemic diseases, organic brain pathology or psychiatric illnesses must be ruled out before a diagnosis of Charles Bonnet syndrome can be made.
Management Of Charles Bonnet syndrome
Mainstay of treatment of the syndrome involves recognition, reassurance and patient education. Pharmacotherapy has not universally proved to be useful although drugs like carbamazepine, haloperidol and cisapride have been used.
Ophthalmologists and physicians must be aware of this condition as it can occur in many patients with visual impairment. Elderly people with visual impairment should be asked whether they have complex hallucinations. Once other causes of hallucination have been eliminated a diagnosis of Charles Bonnet syndrome can be made. Firm reassurance that the syndrome is not related to mental illness is in itself a major relief to an elderly person.
Why common Man Should Know About Charles Bonnet syndrome?
Every house has old people. Any old person who is visually impaired can develop visual hallucinations. In such case, people may think whether person has developed a psychiatric problem and may neglect or hate him. if one knows that this is a case of Charles Bonnet syndrome, this attitude will change.
