Charles Bonnet syndrome (CBS) is a disease in which visual hallucinations occur as a result of vision loss. CBS is not thought to be related to psychosis or dementia and people with CBS are aware that their hallucinations are not real. The hallucinations people with CBS experience can be described as simple or complex. Simple hallucinations include shapes and patterns, while complex include images of people, vehicles, animals, and plants. Hallucination episodes can range from a few seconds to hours and may recur over the course of several days to years. 

The cause of CBS is not well understood, but it is thought to be related to the brain continuing to interpret images, even in their absence. There are many underlying diseases of vision loss that are associated with CBS, such as macular degeneration and stroke. Hallucinations may resolve in instances where the the underlying vision issue can be corrected (such as with cataracts). Treatment differs depending on the impact symptoms have on a person's life. Some people are taught to block their hallucinations, while others may benefit from antipsychotic medications.

Hallucinations associated with Charles Bonnet syndrome (CBS) can be simple, non-formed images such as lines, light flashes, patterns, or geometric shapes. They also can be complex, such as images of people, animals, or scenes. They are usually not disturbing and do not involve other senses. People with CBS are generally aware that the hallucinations are not real and do not have an underlying psychological disease or dementia.

The timing and frequency of hallucinations can vary widely. The hallucinations tend to occur upon awakening. They usually last several minutes, but can be seconds or hours. Typically, there is a distinctive pattern to the timing and frequency of the hallucinations. The degree and complexity of the hallucinations also vary among individuals, but no association has been found between the complexity of the hallucinations and the severity of visual loss.

Associated symptoms depend upon the underlying disorder producing the visual loss. For example, strokes involving the visual pathways produce vision loss and sometimes other neurologic deficits, while macular degeneration and diabetic retinopathy produce loss of vision loss without neurologic deficits.

While there is currently no single treatment that is effective for all cases of Charles Bonnet syndrome, there are steps that patients can take that might have a positive effect:

• Optimal eye care and regular visits to the ophthalmologist
• Low vision aids to help maximize any existing vision
• Avoidance of conditions known to aggravate CBS such as stress, anxiety, social isolation, and sensory deprivation
• Reassurance that the hallucinated images are benign and that treatment is an option
• Medications including olanzapine, quetiapine, carbamazepine, clonazepam, and donepezil
• Certain rapid eye movements or blinking to help suppress the hallucination
• Repetitive transcranial magnetic stimulation

The Charles Bonnet Syndrome Foundation has additional information.