Illustration by: casajordi
Chances are you’ve never heard of Charles Bonnet, or even of the eye condition that bears his name. But his story, and the nature of the condition was the first to diagnose, are both very interesting.
Bonnet was a Swiss philosopher and naturalist who lived from 1720-1793. In 1760, he noted that his 87-year-old grandfather, who suffered from near-total vision loss due to cataracts, was seeing things. Literally. His complex, vivid visual hallucinations included men, women, birds, buildings, tapestries and carriages. His grandfather was otherwise in good health, both mentally and physically.
The condition Bonnet first noted 250 years ago is now known as Charles Bonnet syndrome. One reason for a lack of general awareness about it may be due to the stigma associated with visual hallucinations: people who experience them may naturally fear they have a mental illness, and thus be reluctant to report them.
But, as is the case with Charles Bonnet syndrome, visual hallucinations are not necessarily symptomatic of mental illness, or of an underlying serious condition such as Parkinson’s disease and Alzheimer’s disease, with which they are sometimes associated.
According to Lighthouse International, roughly one third of people with low vision develop Charles Bonnet syndrome. That includes people with serious eye conditions including age-related macular degeneration, cataracts, diabetic retinopathy, and other eye disorders. The hallucinations are more likely to occur while awake, alone, and in dim light, or during periods of physical inactivity.
The visual hallucinations associated with Charles Bonnet syndrome usually dissipate within a year or 18 months, apparently because of adjustments the brain makes to accommodate vision loss. Although treatment is available, once patients are reassured that their visual hallucinations are not symptomatic of mental illness or serious disease, many learn to live with them.
It goes without saying that you should report any changes to your vision—which certainly includes seeing things that you know aren’t there—to a physician, but I will say it anyway. It may be a difficult call to make, but it will be an important one.
