Kamal S. Bhatia, MD

CASE Seeing friends
Mr. B, age 91, presents to the emergency room (ER) for hip pain. As he is being evalu­ated, he asks a nurse to tell the “other people” around her to leave so that he can have pri­vacy. As clarification, Mr. B reports visual hal­lucinations, which prompts the ER physician to request a psychiatry consult.

Mr. B is alert and oriented to time, place, and person when he is evaluated by the on-call psychiatry resident. He reports that he has been seeing several unusual things for the last 4 to 5 months. Asked to elaborate, Mr. B admits seeing colorful and vivid images of people around him. These people come and go as they like; rarely, they talk to him. He describes the conversations as “a constant chatter” in the background and adds that it is difficult to understand what they are talking about.

Mr. B states that he has been “seeing” a cou­ple of people on a regular basis, and they are “sort of like my friends.” He endorses that these people often sing songs or dance for him. He states that, sometimes, these “friends” bring 3 or 4 friends and, although he could not make out their faces clearly, “they all are around me.” He describes the people he sees as “nice people” and does not report being scared or frightened by them.

Mr. B does not report paranoia, and denies command-type hallucinations. He and his family report no unusual changes in behavior in recent months. The medical history is remarkable for atrial fibrillation, coronary artery disease, chronic obstructive pulmonary disease, age-related macular degeneration, and glaucoma.

Mr. B denies having any ongoing mood or anxiety symptoms. He states that he knows these people are “probably not real,” and they do not bother him and just keep him company.

What could be causing Mr. B’s hallucinations?
   a) a stroke
   b) late-onset schizophrenia
   c) dementia
   d) Charles Bonnet syndrome

The authors’ observations
Visual hallucinations among geriatric pa-tients are a common and confusing pre­sentation. In addition to several medical causes for this presentation (Table 1), con­sider Charles Bonnet syndrome in patients with visual loss, presenting as visual hal­lucinations with intact insight and absence of a mental illness. Other conditions to con­sider in the differential diagnosis include Parkinson’s disease, dementia with Lewy bodies, schizophrenia, seizures, migraine, and stroke, including lesions of the thala­mus or brain stem.

Charles Bonnet syndrome was first described by Swiss philosopher Charles Bonnet in the 18th century. He reported vivid visual hallucinations in his visually impaired grandfather (bilateral cataracts).¹

It is important to recognize this syn­drome because patients can present across different specialties, including psychia­try, ophthalmology, neurology, geriat­ric medicine, and family medicine.² As life expectancy increases, this condition might be seen more often. It is prudent to identify, intervene, and refer as appropri­ate, in addition to educating patients and caregivers about the nature and course of the condition. 

EVALUATION Not psychotic
Mr. B reports good sleep and appetite. He denies using alcohol or illicit drugs. He states he slipped in the bathroom the day before coming to the ER, but denies other recent falls or injuries. Other than hip pain, he has no other physical complaints. His medication regimen includes aspirin, lisinopril, lovastatin, and metoprolol.

The ER team diagnoses a hip fracture. Mr. B is transferred to the orthopedic service; the psychiatry consult team continues to fol­low him. Mental status examination is unre­markable other than the visual hallucinations. His speech is clear, non-pressured, with goal-directed thought processing. Mini-Mental State Examination score is 23/30 with Mr. B having difficulty with object drawing and 3-object recall. Brief cognitive examination in the ER is unremarkable.

The orthopedic team decides on conserva­tive management of the hip fracture. There is no evidence of infection. Mr. B is afebrile with clear sensorium; complete blood cell count and normal liver function tests are normal; urinalysis and urine drug screen are negative; and chest radiography is unremarkable. CT and MRI of the head are unremarkable.

After 1 week in the hospital, Mr. B contin­ues to experience vivid visual imagery. No signs of active infection are found. An oph­thalmologist is consulted, who confirms Mr. B’s earlier diagnosis of glaucoma and age-related macular degeneration but does not recommend further treatment. Visual field test by confrontation is normal, with normal visual reflexes.

The authors’ observations
The reported prevalence of Charles Bonnet syndrome among visually impaired peo­ple varies from study to study—from as low as 0.4% to as high as 63%.^3-6 The rea­son for such variation can be attributed to several variables:
   • underdiagnosis
   • misdiagnosis
   • underreporting by patients because of the benign nature of the hallucinations
   • patients’ reluctance to report visual hallucinations because of fear of being labeled “mentally ill.”^7,8

Symptoms
There are no specific diagnostic criteria for Charles Bonnet syndrome (Table 2). However, the following are generally accepted for diagnosis⁹:
   • grossly intact cognition, although mild cognitive impairment may be present in some cases¹⁰
    • underlying visual disorder, usually acquired, such as glaucoma, age-related macular degeneration, diabetic retinopathy, central retinal artery occlusion, and optic neuritis^3,4,11
   • no hallucinations or perceptive difficul­ties in other sensory modalities
   • generally intact insight
   • absence of delusions
   • absence of other neurologic, psychiat­ric, toxic, or metabolic conditions; medical causes of delirium must be ruled out.

Hallucinations might not be disturb­ing to the patient. Hallucinations could be simple (light flashes, lines, or geomet­ric shapes) or complex (faces, figures, or scenes),¹² and perceived as in color or in black and white. Hallucinations mostly are pleasant and rarely have any emotional impact or meaning. Although hallucina­tions are almost exclusively visual, they can be accompanied by noise or auditory hallucinations.^13,14

Other characteristics of Charles Bonnet syndrome include:  
   • typical age of onset is approximately 72 years (range, 70 to 92 years)  
   • no sex distinction has been identified  
   • episodes can last from a few seconds to few hours; the syndrome may last a few days or a few years⁵     
   • it is not uncommon for episodes to occur in clusters, followed by symptom-free intervals and recurrences  
   • symptoms tend to fade away as patients progress to complete loss of sight.¹⁵

The course of Charles Bonnet syndrome is uncertain and unpredictable and the epi­sodic nature can be frustrating for both patient and clinician. The syndrome could be misdiagnosed as a psychiatric condition.

Pathophysiology
The precise mechanism behind simple or complex vivid hallucinations in persons with Charles Bonnet syndrome is unclear. Several theories have been proposed.

Release theory proposes a loss of input to the primary visual areas, which decreases cortical inhibition and further causes disin­hibition of visual association areas, thereby “releasing” visual hallucinations.¹⁶ Research suggests that this might be an attempt by surviving neurons to recover vision. Loss of input somehow causes surviving neurons to adapt by increased sensitivity to residual visual stimuli.

Deafferentation theory. This relatively new theory proposes deafferentation of the visual sensory pathway, which, in turn, causes disinhibition of neurons in the visual cortical regions, thereby caus­ing them to fire spontaneously. This could cause a sensation analogous to phantom limb pain, which would be called “phan­tom vision presence of brain activity in the absence of an actual visual input.” Further, biochemical and molecular changes have been proposed to explain the deafferenta­tion theory.¹⁷

Neurobiological evidence. Limited data are available for a neurobiological basis to visual hallucinations in Charles Bonnet syndrome. A few studies have used func­tional MRI and single-photon emission CT and reported possible association of visual hallucinations to specific visual areas.^18,19

Risk factors
Social or physical isolation, loneliness, low extraversion, and shyness are risk factors for Charles Bonnet syndrome in visually impaired people.²⁰ Sensory deprivation and low level of arousal favor the occur­rence of hallucinations.⁵ Rate of vision loss—not the nature of pathology or sever­ity of visual impairment—has been sug­gested to increase the risk of developing Charles Bonnet syndrome.²¹

What are the treatment options for Charles Bonnet syndrome?
   a) begin an antipsychotic
   b) do nothing; there is no cure
   c) educate the patient about the nature of the hallucinations
   d) refer the patient to an ophthalmologist for evaluation of vision loss

Treatment
There are several modalities to manage visual hallucinations in a patient with Charles Bonnet syndrome (Table 3). After ruling out medical and other psychiat­ric causes of visual hallucinations, treat­ment might not be indicated if the patient is not disturbed by the hallucinations. In most cases, reassurance and educating the patient and family about the benign nature of the visual hallucinations is all that is needed.

For patients who are disturbed by these visions or for whom there is a treatable cause, treatment could include cataract removal, medical therapy to reduce intra­ocular pressure in glaucoma, treatment of diabetic retinopathy, or laser photoco­agulation. These treatments are associ­ated with a reduction in hallucinations.²²

In some cases, hallucinations disappear as visual acuity deteriorates. Psychotropics have been used to treat Charles Bonnet syndrome, including:
   • antipsychotics, including haloperi­dol, risperidone, and olanzapine
   • anticonvulsants, including valproic acid, gabapentin, and carbamazepine
   • antidepressants, including mirtazap­ine and venlafaxine.^23-30

Some experts recommend a conserva­tive approach, which might be justified because some cases of Charles Bonnet syndrome are episodic and remit sponta­neously.³¹ Again, however, consider phar­macotherapy if a patient is disturbed by hallucinations or if hallucinations impair overall functioning.

TREATMENT Education
After discussion with Mr. B and his family, he is started on risperidone, 1 mg at bedtime, and the psychiatric team provides informa­tion about the nature of Charles Bonnet syndrome. Mr. B reportedly takes this medi­cation for a few days and then stops because he does not want the visual hallucinations to go away.

The psychiatry team sees Mr. B before dis­charge. He and his family are educated about the benign nature of the syndrome, the need for continued family support, and the fact that hallucinations will have minimal or no impli­cations for his life.

The authors’ observations
It is important to remember that a visual description of hallucinations in Charles Bonnet syndrome can be quite vivid, and that the patient might not identify his hal­lucinations as such or consider them as a problem. Be careful not to dismiss the patient’s complaints as a primary psychi­atric condition. It also is important to be mindful of the patient’s concerns with a psychiatric diagnosis; detailed discussion with the patient is helpful in most cases. A more comprehensive and empathetic approach to care could go a long way to sustain quality of life for these patients.

Bottom Line
Charles Bonnet syndrome is characterized by visual hallucinations in patients with visual impairment who have intact insight and an absence of mental illness. Taking a thorough history can help rule out medical and psychiatric causes of visual hallucinations. Educate patients and family about the nature of the hallucinations. In some cases, a psychotropic may be indicated.

Related Resources
• Nguyen ND, Osterweil D, Hoffman J. Charles Bonnet syn­drome: treating nonpsychiatric hallucinations. Consult Pharm. 2013;28(3):184-188.
• Lapid MI, Burton MC, Chang MT, et al. Clinical phenomenology and mortality in Charles Bonnet syndrome. J Geriatr Psychiatry Neurol. 2013;26(1):3-9.

Drug Brand Names
Carbamazepine • Tegretol                          Mirtazapine • Remeron
Gabapentin • Neurontin                              Olanzapine • Zyprexa
Haloperidol • Haldol                                   Risperidone • Risperdal
Lisinopril • Prinivil, Zestril                           Valproic acid • Depakene
Lovastatin • Mevacor                                  Venlafaxine • Effexor
Metoprolol • Lopressor

Acknowledgement
The authors acknowledge Barry Liskow, MD, Vice Chair of Psychiatry, Kansas University Medical Center, Kansas City, Kansas, for providing both insight into the topic and useful feedback on the manuscript.

Disclosures
The authors report no financial relationships with any company whose products are mentioned in this article or with manufacturers of competing products.

CASE Seeing friends
Mr. B, age 91, presents to the emergency room (ER) for hip pain. As he is being evalu­ated, he asks a nurse to tell the “other people” around her to leave so that he can have pri­vacy. As clarification, Mr. B reports visual hal­lucinations, which prompts the ER physician to request a psychiatry consult.

Mr. B is alert and oriented to time, place, and person when he is evaluated by the on-call psychiatry resident. He reports that he has been seeing several unusual things for the last 4 to 5 months. Asked to elaborate, Mr. B admits seeing colorful and vivid images of people around him. These people come and go as they like; rarely, they talk to him. He describes the conversations as “a constant chatter” in the background and adds that it is difficult to understand what they are talking about.

Mr. B states that he has been “seeing” a cou­ple of people on a regular basis, and they are “sort of like my friends.” He endorses that these people often sing songs or dance for him. He states that, sometimes, these “friends” bring 3 or 4 friends and, although he could not make out their faces clearly, “they all are around me.” He describes the people he sees as “nice people” and does not report being scared or frightened by them.

Mr. B does not report paranoia, and denies command-type hallucinations. He and his family report no unusual changes in behavior in recent months. The medical history is remarkable for atrial fibrillation, coronary artery disease, chronic obstructive pulmonary disease, age-related macular degeneration, and glaucoma.

Mr. B denies having any ongoing mood or anxiety symptoms. He states that he knows these people are “probably not real,” and they do not bother him and just keep him company.

What could be causing Mr. B’s hallucinations?
   a) a stroke
   b) late-onset schizophrenia
   c) dementia
   d) Charles Bonnet syndrome

The authors’ observations
Visual hallucinations among geriatric pa-tients are a common and confusing pre­sentation. In addition to several medical causes for this presentation (Table 1), con­sider Charles Bonnet syndrome in patients with visual loss, presenting as visual hal­lucinations with intact insight and absence of a mental illness. Other conditions to con­sider in the differential diagnosis include Parkinson’s disease, dementia with Lewy bodies, schizophrenia, seizures, migraine, and stroke, including lesions of the thala­mus or brain stem.

Charles Bonnet syndrome was first described by Swiss philosopher Charles Bonnet in the 18th century. He reported vivid visual hallucinations in his visually impaired grandfather (bilateral cataracts).¹

It is important to recognize this syn­drome because patients can present across different specialties, including psychia­try, ophthalmology, neurology, geriat­ric medicine, and family medicine.² As life expectancy increases, this condition might be seen more often. It is prudent to identify, intervene, and refer as appropri­ate, in addition to educating patients and caregivers about the nature and course of the condition. 

EVALUATION Not psychotic
Mr. B reports good sleep and appetite. He denies using alcohol or illicit drugs. He states he slipped in the bathroom the day before coming to the ER, but denies other recent falls or injuries. Other than hip pain, he has no other physical complaints. His medication regimen includes aspirin, lisinopril, lovastatin, and metoprolol.

The ER team diagnoses a hip fracture. Mr. B is transferred to the orthopedic service; the psychiatry consult team continues to fol­low him. Mental status examination is unre­markable other than the visual hallucinations. His speech is clear, non-pressured, with goal-directed thought processing. Mini-Mental State Examination score is 23/30 with Mr. B having difficulty with object drawing and 3-object recall. Brief cognitive examination in the ER is unremarkable.

The orthopedic team decides on conserva­tive management of the hip fracture. There is no evidence of infection. Mr. B is afebrile with clear sensorium; complete blood cell count and normal liver function tests are normal; urinalysis and urine drug screen are negative; and chest radiography is unremarkable. CT and MRI of the head are unremarkable.

After 1 week in the hospital, Mr. B contin­ues to experience vivid visual imagery. No signs of active infection are found. An oph­thalmologist is consulted, who confirms Mr. B’s earlier diagnosis of glaucoma and age-related macular degeneration but does not recommend further treatment. Visual field test by confrontation is normal, with normal visual reflexes.

The authors’ observations
The reported prevalence of Charles Bonnet syndrome among visually impaired peo­ple varies from study to study—from as low as 0.4% to as high as 63%.^3-6 The rea­son for such variation can be attributed to several variables:
   • underdiagnosis
   • misdiagnosis
   • underreporting by patients because of the benign nature of the hallucinations
   • patients’ reluctance to report visual hallucinations because of fear of being labeled “mentally ill.”^7,8

Symptoms
There are no specific diagnostic criteria for Charles Bonnet syndrome (Table 2). However, the following are generally accepted for diagnosis⁹:
   • grossly intact cognition, although mild cognitive impairment may be present in some cases¹⁰
    • underlying visual disorder, usually acquired, such as glaucoma, age-related macular degeneration, diabetic retinopathy, central retinal artery occlusion, and optic neuritis^3,4,11
   • no hallucinations or perceptive difficul­ties in other sensory modalities
   • generally intact insight
   • absence of delusions
   • absence of other neurologic, psychiat­ric, toxic, or metabolic conditions; medical causes of delirium must be ruled out.

Hallucinations might not be disturb­ing to the patient. Hallucinations could be simple (light flashes, lines, or geomet­ric shapes) or complex (faces, figures, or scenes),¹² and perceived as in color or in black and white. Hallucinations mostly are pleasant and rarely have any emotional impact or meaning. Although hallucina­tions are almost exclusively visual, they can be accompanied by noise or auditory hallucinations.^13,14

Other characteristics of Charles Bonnet syndrome include:  
   • typical age of onset is approximately 72 years (range, 70 to 92 years)  
   • no sex distinction has been identified  
   • episodes can last from a few seconds to few hours; the syndrome may last a few days or a few years⁵     
   • it is not uncommon for episodes to occur in clusters, followed by symptom-free intervals and recurrences  
   • symptoms tend to fade away as patients progress to complete loss of sight.¹⁵

The course of Charles Bonnet syndrome is uncertain and unpredictable and the epi­sodic nature can be frustrating for both patient and clinician. The syndrome could be misdiagnosed as a psychiatric condition.

Pathophysiology
The precise mechanism behind simple or complex vivid hallucinations in persons with Charles Bonnet syndrome is unclear. Several theories have been proposed.

Release theory proposes a loss of input to the primary visual areas, which decreases cortical inhibition and further causes disin­hibition of visual association areas, thereby “releasing” visual hallucinations.¹⁶ Research suggests that this might be an attempt by surviving neurons to recover vision. Loss of input somehow causes surviving neurons to adapt by increased sensitivity to residual visual stimuli.

Deafferentation theory. This relatively new theory proposes deafferentation of the visual sensory pathway, which, in turn, causes disinhibition of neurons in the visual cortical regions, thereby caus­ing them to fire spontaneously. This could cause a sensation analogous to phantom limb pain, which would be called “phan­tom vision presence of brain activity in the absence of an actual visual input.” Further, biochemical and molecular changes have been proposed to explain the deafferenta­tion theory.¹⁷

Neurobiological evidence. Limited data are available for a neurobiological basis to visual hallucinations in Charles Bonnet syndrome. A few studies have used func­tional MRI and single-photon emission CT and reported possible association of visual hallucinations to specific visual areas.^18,19

Risk factors
Social or physical isolation, loneliness, low extraversion, and shyness are risk factors for Charles Bonnet syndrome in visually impaired people.²⁰ Sensory deprivation and low level of arousal favor the occur­rence of hallucinations.⁵ Rate of vision loss—not the nature of pathology or sever­ity of visual impairment—has been sug­gested to increase the risk of developing Charles Bonnet syndrome.²¹

What are the treatment options for Charles Bonnet syndrome?
   a) begin an antipsychotic
   b) do nothing; there is no cure
   c) educate the patient about the nature of the hallucinations
   d) refer the patient to an ophthalmologist for evaluation of vision loss

Treatment
There are several modalities to manage visual hallucinations in a patient with Charles Bonnet syndrome (Table 3). After ruling out medical and other psychiat­ric causes of visual hallucinations, treat­ment might not be indicated if the patient is not disturbed by the hallucinations. In most cases, reassurance and educating the patient and family about the benign nature of the visual hallucinations is all that is needed.

For patients who are disturbed by these visions or for whom there is a treatable cause, treatment could include cataract removal, medical therapy to reduce intra­ocular pressure in glaucoma, treatment of diabetic retinopathy, or laser photoco­agulation. These treatments are associ­ated with a reduction in hallucinations.²²

In some cases, hallucinations disappear as visual acuity deteriorates. Psychotropics have been used to treat Charles Bonnet syndrome, including:
   • antipsychotics, including haloperi­dol, risperidone, and olanzapine
   • anticonvulsants, including valproic acid, gabapentin, and carbamazepine
   • antidepressants, including mirtazap­ine and venlafaxine.^23-30

Some experts recommend a conserva­tive approach, which might be justified because some cases of Charles Bonnet syndrome are episodic and remit sponta­neously.³¹ Again, however, consider phar­macotherapy if a patient is disturbed by hallucinations or if hallucinations impair overall functioning.

TREATMENT Education
After discussion with Mr. B and his family, he is started on risperidone, 1 mg at bedtime, and the psychiatric team provides informa­tion about the nature of Charles Bonnet syndrome. Mr. B reportedly takes this medi­cation for a few days and then stops because he does not want the visual hallucinations to go away.

The psychiatry team sees Mr. B before dis­charge. He and his family are educated about the benign nature of the syndrome, the need for continued family support, and the fact that hallucinations will have minimal or no impli­cations for his life.

The authors’ observations
It is important to remember that a visual description of hallucinations in Charles Bonnet syndrome can be quite vivid, and that the patient might not identify his hal­lucinations as such or consider them as a problem. Be careful not to dismiss the patient’s complaints as a primary psychi­atric condition. It also is important to be mindful of the patient’s concerns with a psychiatric diagnosis; detailed discussion with the patient is helpful in most cases. A more comprehensive and empathetic approach to care could go a long way to sustain quality of life for these patients.

Bottom Line
Charles Bonnet syndrome is characterized by visual hallucinations in patients with visual impairment who have intact insight and an absence of mental illness. Taking a thorough history can help rule out medical and psychiatric causes of visual hallucinations. Educate patients and family about the nature of the hallucinations. In some cases, a psychotropic may be indicated.

Related Resources
• Nguyen ND, Osterweil D, Hoffman J. Charles Bonnet syn­drome: treating nonpsychiatric hallucinations. Consult Pharm. 2013;28(3):184-188.
• Lapid MI, Burton MC, Chang MT, et al. Clinical phenomenology and mortality in Charles Bonnet syndrome. J Geriatr Psychiatry Neurol. 2013;26(1):3-9.

Drug Brand Names
Carbamazepine • Tegretol                          Mirtazapine • Remeron
Gabapentin • Neurontin                              Olanzapine • Zyprexa
Haloperidol • Haldol                                   Risperidone • Risperdal
Lisinopril • Prinivil, Zestril                           Valproic acid • Depakene
Lovastatin • Mevacor                                  Venlafaxine • Effexor
Metoprolol • Lopressor

Acknowledgement
The authors acknowledge Barry Liskow, MD, Vice Chair of Psychiatry, Kansas University Medical Center, Kansas City, Kansas, for providing both insight into the topic and useful feedback on the manuscript.

Disclosures
The authors report no financial relationships with any company whose products are mentioned in this article or with manufacturers of competing products.

CASE Seeing friends
Mr. B, age 91, presents to the emergency room (ER) for hip pain. As he is being evalu­ated, he asks a nurse to tell the “other people” around her to leave so that he can have pri­vacy. As clarification, Mr. B reports visual hal­lucinations, which prompts the ER physician to request a psychiatry consult.

Mr. B is alert and oriented to time, place, and person when he is evaluated by the on-call psychiatry resident. He reports that he has been seeing several unusual things for the last 4 to 5 months. Asked to elaborate, Mr. B admits seeing colorful and vivid images of people around him. These people come and go as they like; rarely, they talk to him. He describes the conversations as “a constant chatter” in the background and adds that it is difficult to understand what they are talking about.

Mr. B states that he has been “seeing” a cou­ple of people on a regular basis, and they are “sort of like my friends.” He endorses that these people often sing songs or dance for him. He states that, sometimes, these “friends” bring 3 or 4 friends and, although he could not make out their faces clearly, “they all are around me.” He describes the people he sees as “nice people” and does not report being scared or frightened by them.

Mr. B does not report paranoia, and denies command-type hallucinations. He and his family report no unusual changes in behavior in recent months. The medical history is remarkable for atrial fibrillation, coronary artery disease, chronic obstructive pulmonary disease, age-related macular degeneration, and glaucoma.

Mr. B denies having any ongoing mood or anxiety symptoms. He states that he knows these people are “probably not real,” and they do not bother him and just keep him company.

What could be causing Mr. B’s hallucinations?
   a) a stroke
   b) late-onset schizophrenia
   c) dementia
   d) Charles Bonnet syndrome

The authors’ observations
Visual hallucinations among geriatric pa-tients are a common and confusing pre­sentation. In addition to several medical causes for this presentation (Table 1), con­sider Charles Bonnet syndrome in patients with visual loss, presenting as visual hal­lucinations with intact insight and absence of a mental illness. Other conditions to con­sider in the differential diagnosis include Parkinson’s disease, dementia with Lewy bodies, schizophrenia, seizures, migraine, and stroke, including lesions of the thala­mus or brain stem.

Charles Bonnet syndrome was first described by Swiss philosopher Charles Bonnet in the 18th century. He reported vivid visual hallucinations in his visually impaired grandfather (bilateral cataracts).¹

It is important to recognize this syn­drome because patients can present across different specialties, including psychia­try, ophthalmology, neurology, geriat­ric medicine, and family medicine.² As life expectancy increases, this condition might be seen more often. It is prudent to identify, intervene, and refer as appropri­ate, in addition to educating patients and caregivers about the nature and course of the condition. 

EVALUATION Not psychotic
Mr. B reports good sleep and appetite. He denies using alcohol or illicit drugs. He states he slipped in the bathroom the day before coming to the ER, but denies other recent falls or injuries. Other than hip pain, he has no other physical complaints. His medication regimen includes aspirin, lisinopril, lovastatin, and metoprolol.

The ER team diagnoses a hip fracture. Mr. B is transferred to the orthopedic service; the psychiatry consult team continues to fol­low him. Mental status examination is unre­markable other than the visual hallucinations. His speech is clear, non-pressured, with goal-directed thought processing. Mini-Mental State Examination score is 23/30 with Mr. B having difficulty with object drawing and 3-object recall. Brief cognitive examination in the ER is unremarkable.

The orthopedic team decides on conserva­tive management of the hip fracture. There is no evidence of infection. Mr. B is afebrile with clear sensorium; complete blood cell count and normal liver function tests are normal; urinalysis and urine drug screen are negative; and chest radiography is unremarkable. CT and MRI of the head are unremarkable.

After 1 week in the hospital, Mr. B contin­ues to experience vivid visual imagery. No signs of active infection are found. An oph­thalmologist is consulted, who confirms Mr. B’s earlier diagnosis of glaucoma and age-related macular degeneration but does not recommend further treatment. Visual field test by confrontation is normal, with normal visual reflexes.

The authors’ observations
The reported prevalence of Charles Bonnet syndrome among visually impaired peo­ple varies from study to study—from as low as 0.4% to as high as 63%.^3-6 The rea­son for such variation can be attributed to several variables:
   • underdiagnosis
   • misdiagnosis
   • underreporting by patients because of the benign nature of the hallucinations
   • patients’ reluctance to report visual hallucinations because of fear of being labeled “mentally ill.”^7,8

Symptoms
There are no specific diagnostic criteria for Charles Bonnet syndrome (Table 2). However, the following are generally accepted for diagnosis⁹:
   • grossly intact cognition, although mild cognitive impairment may be present in some cases¹⁰
    • underlying visual disorder, usually acquired, such as glaucoma, age-related macular degeneration, diabetic retinopathy, central retinal artery occlusion, and optic neuritis^3,4,11
   • no hallucinations or perceptive difficul­ties in other sensory modalities
   • generally intact insight
   • absence of delusions
   • absence of other neurologic, psychiat­ric, toxic, or metabolic conditions; medical causes of delirium must be ruled out.

Hallucinations might not be disturb­ing to the patient. Hallucinations could be simple (light flashes, lines, or geomet­ric shapes) or complex (faces, figures, or scenes),¹² and perceived as in color or in black and white. Hallucinations mostly are pleasant and rarely have any emotional impact or meaning. Although hallucina­tions are almost exclusively visual, they can be accompanied by noise or auditory hallucinations.^13,14

Other characteristics of Charles Bonnet syndrome include:  
   • typical age of onset is approximately 72 years (range, 70 to 92 years)  
   • no sex distinction has been identified  
   • episodes can last from a few seconds to few hours; the syndrome may last a few days or a few years⁵     
   • it is not uncommon for episodes to occur in clusters, followed by symptom-free intervals and recurrences  
   • symptoms tend to fade away as patients progress to complete loss of sight.¹⁵

The course of Charles Bonnet syndrome is uncertain and unpredictable and the epi­sodic nature can be frustrating for both patient and clinician. The syndrome could be misdiagnosed as a psychiatric condition.

Pathophysiology
The precise mechanism behind simple or complex vivid hallucinations in persons with Charles Bonnet syndrome is unclear. Several theories have been proposed.

Release theory proposes a loss of input to the primary visual areas, which decreases cortical inhibition and further causes disin­hibition of visual association areas, thereby “releasing” visual hallucinations.¹⁶ Research suggests that this might be an attempt by surviving neurons to recover vision. Loss of input somehow causes surviving neurons to adapt by increased sensitivity to residual visual stimuli.

Deafferentation theory. This relatively new theory proposes deafferentation of the visual sensory pathway, which, in turn, causes disinhibition of neurons in the visual cortical regions, thereby caus­ing them to fire spontaneously. This could cause a sensation analogous to phantom limb pain, which would be called “phan­tom vision presence of brain activity in the absence of an actual visual input.” Further, biochemical and molecular changes have been proposed to explain the deafferenta­tion theory.¹⁷

Neurobiological evidence. Limited data are available for a neurobiological basis to visual hallucinations in Charles Bonnet syndrome. A few studies have used func­tional MRI and single-photon emission CT and reported possible association of visual hallucinations to specific visual areas.^18,19

Risk factors
Social or physical isolation, loneliness, low extraversion, and shyness are risk factors for Charles Bonnet syndrome in visually impaired people.²⁰ Sensory deprivation and low level of arousal favor the occur­rence of hallucinations.⁵ Rate of vision loss—not the nature of pathology or sever­ity of visual impairment—has been sug­gested to increase the risk of developing Charles Bonnet syndrome.²¹

What are the treatment options for Charles Bonnet syndrome?
   a) begin an antipsychotic
   b) do nothing; there is no cure
   c) educate the patient about the nature of the hallucinations
   d) refer the patient to an ophthalmologist for evaluation of vision loss

Treatment
There are several modalities to manage visual hallucinations in a patient with Charles Bonnet syndrome (Table 3). After ruling out medical and other psychiat­ric causes of visual hallucinations, treat­ment might not be indicated if the patient is not disturbed by the hallucinations. In most cases, reassurance and educating the patient and family about the benign nature of the visual hallucinations is all that is needed.

For patients who are disturbed by these visions or for whom there is a treatable cause, treatment could include cataract removal, medical therapy to reduce intra­ocular pressure in glaucoma, treatment of diabetic retinopathy, or laser photoco­agulation. These treatments are associ­ated with a reduction in hallucinations.²²

In some cases, hallucinations disappear as visual acuity deteriorates. Psychotropics have been used to treat Charles Bonnet syndrome, including:
   • antipsychotics, including haloperi­dol, risperidone, and olanzapine
   • anticonvulsants, including valproic acid, gabapentin, and carbamazepine
   • antidepressants, including mirtazap­ine and venlafaxine.^23-30

Some experts recommend a conserva­tive approach, which might be justified because some cases of Charles Bonnet syndrome are episodic and remit sponta­neously.³¹ Again, however, consider phar­macotherapy if a patient is disturbed by hallucinations or if hallucinations impair overall functioning.

TREATMENT Education
After discussion with Mr. B and his family, he is started on risperidone, 1 mg at bedtime, and the psychiatric team provides informa­tion about the nature of Charles Bonnet syndrome. Mr. B reportedly takes this medi­cation for a few days and then stops because he does not want the visual hallucinations to go away.

The psychiatry team sees Mr. B before dis­charge. He and his family are educated about the benign nature of the syndrome, the need for continued family support, and the fact that hallucinations will have minimal or no impli­cations for his life.

The authors’ observations
It is important to remember that a visual description of hallucinations in Charles Bonnet syndrome can be quite vivid, and that the patient might not identify his hal­lucinations as such or consider them as a problem. Be careful not to dismiss the patient’s complaints as a primary psychi­atric condition. It also is important to be mindful of the patient’s concerns with a psychiatric diagnosis; detailed discussion with the patient is helpful in most cases. A more comprehensive and empathetic approach to care could go a long way to sustain quality of life for these patients.

Bottom Line
Charles Bonnet syndrome is characterized by visual hallucinations in patients with visual impairment who have intact insight and an absence of mental illness. Taking a thorough history can help rule out medical and psychiatric causes of visual hallucinations. Educate patients and family about the nature of the hallucinations. In some cases, a psychotropic may be indicated.

Related Resources
• Nguyen ND, Osterweil D, Hoffman J. Charles Bonnet syn­drome: treating nonpsychiatric hallucinations. Consult Pharm. 2013;28(3):184-188.
• Lapid MI, Burton MC, Chang MT, et al. Clinical phenomenology and mortality in Charles Bonnet syndrome. J Geriatr Psychiatry Neurol. 2013;26(1):3-9.

Drug Brand Names
Carbamazepine • Tegretol                          Mirtazapine • Remeron
Gabapentin • Neurontin                              Olanzapine • Zyprexa
Haloperidol • Haldol                                   Risperidone • Risperdal
Lisinopril • Prinivil, Zestril                           Valproic acid • Depakene
Lovastatin • Mevacor                                  Venlafaxine • Effexor
Metoprolol • Lopressor

Acknowledgement
The authors acknowledge Barry Liskow, MD, Vice Chair of Psychiatry, Kansas University Medical Center, Kansas City, Kansas, for providing both insight into the topic and useful feedback on the manuscript.

Disclosures
The authors report no financial relationships with any company whose products are mentioned in this article or with manufacturers of competing products.