Charles Bonnet was a Swiss philosopher and naturalist, born in Geneva. Among his achievements are researches related to parthenogenesis in aphids, and the development of caterpillars into butterflies, allowing the publication of the treatise on insectology, in 1745; refutation of the theory of epigenesis; writings on psychology; the pioneering use of the word “evolution”, among others.
It was, however, analyzing his grandfather's case, that he possibly came to be better recognized. Considerably elderly, his grandfather, who had a cataract, had visions of people, animals, and buildings that were quite clear and changed in shape, size, and place. Due to the contributions that this philosopher provided, this clinical picture was named Charles Bonnet syndrome.
This syndrome consists of the sudden visualization of silent, sharp, complex and colorful images, which abruptly disappear. They can last a few minutes or even a few hours, and are noticeable even when your eyes are closed. In most cases they are pleasurable, or at least nil.
The affected person usually has visual impairment such as cataracts, glaucoma, age-related macular degeneration, diabetic retinopathy, and temporal arteritis; and is able to recognize the unreality of such views. Furthermore, she has no cognitive disturbances, or significant systemic changes.
Such symptoms are similar to what happens when an amputee “feels” that part of the body that is no longer there. In both cases, these perceptions are related to the loss of sensory information, causing the brain to fill this gap with remembered or imagined sensations.
Despite occurring in several age groups, this syndrome manifests predominantly in the elderly, with a higher incidence among those between 70 and 93 years of age. The picture is often overlooked: either because those close to them believe it is dementia senile, or because the affected individual has this fear, and hides from other people what he has past. Another factor that makes it difficult to identify this condition is the lack of knowledge on the part of some physicians, causing the condition to be misdiagnosed or neglected.
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Considering the aging of the population, and the longer life expectancy that this group has achieved, it is important that these professionals are attentive. Some experts say the best way to discover potential carriers is to ask those patients who have reduced visual acuity whether or not they have visual illusions.
As for the treatment, it focuses on the ocular deficiency that the patient has; but psychological counseling and treatment of associated entities, such as depression, may also be required. In some cases, drugs can also be prescribed.
Unfortunately, in some cases, the condition only disappears when the patient completely loses the ability to see. Either way, blinking, increasing the lighting in the place where you are, or making other changes to the environment; usually accelerate the disappearance of visions.
Knowing that what is happening is not a psychiatric problem, or something more serious, significantly reduces the anguish that many of these people feel. Thus, the earlier Charles Bonnet syndrome is diagnosed, the better the chances that the patient will go on with his life in a healthier way.
By Mariana Araguaia
Biologist, specialist in Environmental Education
Brazil School Team