Source : FISH ’S Clinical psychopathology

Vision

These may be elementary in the form of flashes of light, partly organised in the form of patterns, or completely organised in the form of visions of people, objects or animals. Figures of living things and inanimate objects

may appear against the normally perceived environment or scenic hallucinations can occur in which whole scenes are hallucinated rather like a cinema film.

All varieties of visual hallucination are found in acute organic states but small animals and insects are most often hallucinated in delirium. One patient in delirium tremens described mice carrying suitcases on their backs as they boarded a flight to Lourdes. These hallucinations are usually associated with fear and terror. Patients with delirium tremens are extremely suggestible so that one may be able to persuade the patient to read a blank sheet of paper; one investigator produced a disc of light by pressing on the patient’s eyeball and persuaded him that he could see a dog. Scenic hallucinations are common in psychiatric disorders associated with epilepsy and these patients may also have visions of fire and religious scenes such as the Crucifixion.

Often, visual hallucinations are isolated and do not have any accompanying voices. Sometimes, however, visual and auditory hallucinations co-occur to form a coherent whole. Patients with temporal-lobe epilepsy may have combined auditory and visual hallucinations and some patients with schizophrenia of late onset (especially when the illness is protracted) may see and hear people being tortured, murdered and mutilated.

In some patients, micropsia affects visual hallucinations so that they see tiny people or objects, so-called Lilliputian hallucinations. Unlike the usual organic visual hallucinations, these are accompanied by pleasure and amusement. For example, one patient with delirium tremens was very

pleased when she saw a tiny German band playing on her counterpane.

When these occur in delirium tremens the patient exhibits a combination of child-like pleasure and terror.

Visual hallucinations are more common in acute organic states with clouding of consciousness than in functional psychosis. The disturbance of consciousness makes it difficult for the patient to distinguish between mental images and perceptions, although this is sometimes possible. Visual

hallucinations are extremely rare in schizophrenia, so much so that they should raise a doubt about the diagnosis. Some patients with schizophrenia describe visions and these appear to be pseudo-hallucinations, but on occasion others will insist that their hallucinations are substantial.

Occasionally visual hallucinations occur in the absence of any psychopathology or brain disease and Charles Bonnet syndrome must then be considered as the most likely differential diagnosis.