Charles Bonnet Syndrome: What Nurses Need to Know

Submitted by John Paul Cook, MSN, RN

Tags: Case Study Charles Bonnet Syndrome Guidance for Clinicians Hallucinations treatment Visual Hallucinations

Charles Bonnet Syndrome: What Nurses Need to Know

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John P. Cook
University of Texas at Houston School of Nursing

All nurses know the importance of an accurate history in ensuring that patients receive the proper diagnosis and treatment. Asking the right questions is essential to avoid making assumptions that lead to wrong conclusions. While an accurate history is vital, it can be particularly important when the patient is elderly and visually impaired. It is not uncommon for patients with visual disease such as age-related macular degeneration (ARMD or just AMD), cataracts, or glaucoma to experience visual hallucinations in the absence of any psychological problems. 1,2 These visual hallucinations, reported by either the patient or family, are easily misinterpreted as psychiatric symptoms. Charles Bonnet Syndrome (CBS) is the name given to such hallucinations. 3

This case study describes an elderly stroke patient’s visual hallucinations and shows how they might be misinterpreted.  What follows details how an incomplete assessment can lead to the wrong conclusions and might affect management and ultimately the prognosis. 

What is Charles Bonnet Syndrome?

Charles Bonnet described the syndrome that bears his name in 1760 in Geneva, Switzerland. 4  His grandfather had severe vision loss from cataracts and would see hallucinations of people, birds, scaffolding, and tapestries. 5 Currently, Charles Bonnet Syndrome is the term used to describes the presence of visual hallucinations in people with no known mental illness but have significant vision loss. One theory is that the visual deprivation caused by retinal or occipital damage causes visual hallucinations in a manner similar to phantom limb pain. Another theory is the damaged visual pathway sends distorted images to the brain. 6 CBS hallucinations may appear real and blend perfectly into the background or they may be unreal images such as geometric shapes or dragons. 7

Nurses need to be aware that visual hallucinations are not necessarily indicative of psychiatric symptoms. An understanding that visual impairments can cause visual hallucinations is needed in order to be able to provide the patient with the most appropriate care.

Prevalence of Charles Bonnet Syndrome

With an aging population, degenerative eye diseases such as AMD will become more common. 8 In one study of late stage AMD, 27% of the patients were diagnosed with CBS. 9 In another study, while only 0.47% of all patients had CBS, 15% of low (i.e., impaired) vision patients had CBS. 10 Another large study found the incidence at 11% of visually impaired patients. 11 Also, CBS is not limited to the elderly as it has also been identified in pediatric cases. 12 Neurological disease can also cause CBS even in the absence of ophthalmologic problems. 13

Case Study

Mrs. M, a near centenarian with a history of AMD in both eyes, awoke from her sleep about an hour before her usual awakening time screaming incoherently. She was admitted to the hospital through the emergency department. A cerebral infarction was confirmed by computed tomography, but no thrombolytics were administered because she was determined to be well past the time limit for safe and effective administration. Upon admission, the family provided a list of her medications which consisted of daily simvastatin, levothyroxine, lisinopril, and 81 mg of aspirin. Her medical records were in another city and unavailable to the hospital staff.

Although legally blind in her left eye, Mrs. M was able to read billboards with her right eye while travelling in a motor vehicle. She had given up on her near vision after using a magnifying glass for years. The family accompanying her to the hospital was unware of her past medical history of Charles Bonnet Syndrome diagnosed by her ophthalmologist although they were aware of her reduced acuity. In the two to three decades prior to the cerebrovascular event, Mrs. M had outpatient surgeries for treating breast cancer and skin cancer. Her mobility was impaired due to osteoarthritis and osteoporosis but she ambulated for short distances with the aid of a walker.

Mrs. M’s visual hallucinations were of geometric shapes, usually approximately spherical in shape, either with a solid smooth surface or open like a lattice. They appeared either at ground level or suspended in the air like a balloon. She first admitted to the hallucinations approximately 5 years prior to the cerebral infarction when she was living independently. Mrs. M was reluctant to divulge her hallucinations at first because she was afraid that her children would no longer allow her to live independently. Additionally, she thought her family would be more willing to visit her if they thought she was psychologically normal. Mrs. M eventually concluded that the hallucinations were not caused by a psychiatric problem and decided to reveal them to her only daughter and her ophthalmologist who made the CBS diagnosis. She was relieved to receive confirmation that her CBS hallucinations were normal occurrences in people with significant visual impairment.

One of the key components to patient evaluation is having a complete and accurate baseline to compare the patient’s current state to. Prior to the acute event, the patient was mentally alert without obvious signs of dementia. At the hospital, the staff did not know Mrs. M’s baseline included CBS hallucinations. This affected how they interpreted Mrs. M’s symptoms. Her chart included notations about hallucinations, but nothing about CBS or her visual impairment. When her family asked about her post-infarct prognosis, the hallucinations were mentioned to family as evidence of brain damage caused by the stroke. The family members at the hospital called the daughter urging her to come to the hospital quickly because they thought the prognosis was poor. The hospital staff discussed possible hospice care with the family.

Mrs. M’s daughter was relieved to hear about the hallucinations because she recognized hallucinations as a normal part of her mother’s baseline condition. The daughter asked for a description of the hallucinations and was provided a very familiar description of balloons appearing near the celling. The daughter tried to explain to the nurse and the rest of the family that was a normal occurrence for her mother but this point of view was not immediately accepted. The daughter asked the nurse to chart the description of Mrs. M’s CBS diagnosis but the nurse was dismissive.

Mrs. M did not fully recover to her pre-infarct state but was discharged to a son’s house instead of hospice care. After a period of several weeks, she was moved to an assisted living facility where she was able to regain much of her autonomy and enjoy daily visits from her family.

Guidance for Clinicians

Visual hallucinations have psychosocial implications for both the patient and the patient’s social network. It is important that visual acuity be considered when evaluating visual hallucinations. This is particularly true with the elderly because they are more likely to have visual impairment. CBS etiology should be ruled out before assuming visual hallucinations have a psychiatric etiology. Some patients are sufficiently distressed by CBS that they seek pharmacologic treatment. 14 Eperjesi and Akbarali advised that “the best form of rehabilitation for CBS is disclosure to a sympathetic professional.” 15 Reassurance is all many patients need. Clinicians need education on what to look for.

Menon’s Clinical Analysis Framework

Menon and colleagues published a comprehensive literature review of CBS that is one of the most cited publications on the subject. They made the following points that can be used as a framework for clinical analysis for symptoms. 16

  1. Visual pathology is associated with but not required for CBS symptoms.
  2. It is under recognized with the hallucinations being misattributed to dementia or other psychological dysfunction which may or may not be present.
  3. The hallucinations are usually clear and complex. Patients may report seeing a person or geometric forms. The images may be fixed or move, large or small, black and white or color. They may persist without remission or appear episodically. Remission can be permanent.
  4. Closing the eyes may cause an image to appear, disappear, or cause no change.
  5. Investigators differ on their interpretations of how distressing CBS hallucinations are to patients and how likely patients are to share their experiences.
  6. Many reports describe patients as fearful of being labelled psychologically unstable by either their providers or social networks if they reveal the hallucinations.
  7. Patients report relief when the hallucinations are explained as normal occurrences not of psychiatric origin.

Implications for Nursing Practice

Nurses have a vital role as both patient advocate and confidante. By asking the right questions, nurses can identify possible CBS symptoms and refer accordingly. In this manner, patients can receive the proper diagnosis and treatment. One of the fears the elderly have is becoming institutionalized. An incorrect perception of psychological problems could hasten this at significant social and financial costs. Thus, a correct diagnosis can be helpful in keeping families intact and preserving patient autonomy for as long as possible.

A complete and thorough history should include questions about hallucinations in the visually impaired elderly. This will help ensure proper treatment of CBS and also ensure proper patient evaluation in the future.


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  12. Mewasingh, L. D., Kornreich, C., Christiaens, F., Christophe, C., & Dan, B. (2002). Pediatric phantom vision (Charles Bonnet) syndrome. Pediatric neurology26(2), 143-145.
  13. Ashwin, P. T., & Tsaloumas, M. D. (2007). Complex visual hallucinations (Charles Bonnet syndrome) in the hemianopic visual field following occipital infarction. Journal of the neurological sciences263(1), 184-186.
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