Ophthalmologists gain insight to Charles Bonnet Syndrome hallucinations

November 10, 2008

Visual hallucinations caused by Charles Bonnet Syndrome (CBS) are not infrequent in older individuals with decreased visual function. While individuals who experience these hallucinations, which are usually generic people, animals, patterns, or scenes, understand that what they are seeing is not real and often are not disturbed by the images, they are worried about the reaction of their families, friends, and physicians.

Visual hallucinations caused by Charles Bonnet Syndrome (CBS) are not infrequent in older individuals with decreased visual function. While individuals who experience these hallucinations, which are usually generic people, animals, patterns, or scenes, understand that what they are seeing is not real and often are not disturbed by the images, they are worried about the reaction of their families, friends, and physicians.

According to Lylas G. Mogk, MD, director of the Visual Rehabilitation and Research Center, Henry Ford Health System, Detroit, an ophthalmologist or other clinician who learns about these hallucinations might suspect psychosis, while family members might fear dementia. Thus, it is important for ophthalmologists to understand CBS, be aware that it might be affecting their low-vision patients, and offer reassurance to them and their families.

The images associated with CBS can occur daily or weekly, lasting from seconds to hours, and either disappear spontaneously or with some activity, such as closing one's eyes, Dr. Mogk said. They may be in full color and are capable of movement, but they do not engage or approach the viewer. Individuals usually see the same images repeatedly, such as flowers and trees, groups of people, a quilt-like pattern, or something out of place such as a giraffe on the patio.

Since these hallucinations are more common in the elderly than in other age groups, it has been speculated that they result from a confluence of age and vision loss, Dr. Mogk said. Other theories about the origin also have been proposed, and the syndrome has been linked to loss of contrast sensitivity, sensory deprivation, and social isolation. Since one or more of these factors is likely to be present among individuals suffering from eye conditions that cause deterioration of their vision, the development of CBS in older patients would not be unusual.

Materials in the American Academy of Ophthalmology's SmartSight initiative include information about CBS, and resources also are available elsewhere, Dr. Mogk said.