Charles Bonnet Syndrome in Low Vision Patients (CBS)

Charles Bonnet Syndrome (CBS): Prevalence and Characteristics of Visual Hallucinations. Psychological Profile of the Visually Impaired Patient With CBS

Among patients with chronic and degenerative ocular diseases that cause visual limitations, the presence of Charles Bonnet Syndrome (CBS) may be detected as a comorbidity. CBS is as a phenomenon of complex visual hallucinations occurring in individuals with reduced visual function, in the absence of cognitive alterations, psychiatric and/or neurological conditions. It is estimated that 15.8% of patients with age-related macular degeneration and 13.5% among glaucoma patients have CBS. Prevalence rates vary widely, and this may depend on inconsistent diagnostic criteria, variability in the questions used to determine if an individual has visual hallucinations, and the reluctance of people to admit to having strange visions for fear of being considered mentally ill. Visual hallucinations can be invasive and debilitating, compromising mental health, quality of life, and rehabilitation in visually impaired individuals. Patients may experience confusion, anxiety, anger, paranoia, and social isolation. Regarding psychological aspects, about a third of patients report experiencing distress and fear,higher anxiety and social dysfunction particularly during the initial onset of symptoms and in the terminal stage of the disease.Screening questionnaires will be used.

Study Overview

• Status: Enrolling by invitation
• Conditions: Charles Bonnet Syndrome

Detailed Description

As part of our clinical practice, screening questionnaires will be used to assess the mental health and psychological profile of enrolled patients:

PHQ-9 (Patient Health Questionnaire): A 9-question tool for screening depression, with scores ranging from 0-27 to assess depression severity. Scores above 5 require referral to a clinical psychologist; scores 15+ suggest psychiatric evaluation.

GAD-7 (General Anxiety Disorder): A 7-item tool to screen for generalized anxiety disorder, with scores from 0-21. Scores 10+ require clinical psychologist referral, and 15+ indicate the need for psychiatric evaluation.

SCL-90R (Symptom Checklist-90): A 90-item questionnaire assessing a range of psychological symptoms, including depression, anxiety, and aggression, rated on a Likert scale from 0 to 4.

NEI VFQ25 (National Eye Institute Visual Function Questionnaire): A tool to assess the quality of life related to vision.

GSES (Generalized Self-Efficacy Scale):A 10-item scale to measure perceived self-efficacy and coping mechanisms for stressful life events, rated on a 4-point Likert scale.

PSS (Perceived Stress Scale):A tool to measure how individuals perceive their life as stressful, focusing on unpredictability, uncontrollability, and overwhelm.

GHQ-12 (General Health Questionnaire-12):A 12-item questionnaire to identify general mental health problems, focusing on the past two weeks.

• Study Type: Observational
• Enrollment (Estimated): 640

Contacts and Locations

Study Locations

• Italy
  • Roma, Italy, 00168
    • fondazione Policlinico Universitario A. Gemelli IRCCS, Polo Nazionale Ipovisione

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: N/A

• Sampling Method: Probability Sample

Study Population

Visually impaired individuals with central and peripheral defects who access the center for visual rehabilitation.

Description

Inclusion Criteria:

• Best corrected visual acuity between 1/20 (1.0 LogMAR) and 3.2/10 (0.5 LogMAR) in cases of central vision impairment.
• Residual binocular visual field ≤ 60% in cases of peripheral vision impairment.
• Patients with age-related macular degeneration, Stargardt's disease, or glaucoma.
• Age between 40 and 70 years.
• Signed informed consent.

Exclusion Criteria:

• Age under 40 years.
• Clear cognitive impairments that reduce patient reliability.
• Psychiatric disorders.
• Refusal to sign informed consent to participate in the study.
• Mental State Examination (MMSE) score below 22.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Prevalence of the Charles Bonnet Syndrome	Prevalence of Charles Bonnet Syndrome, calculated as the ratio between the number of visually impaired patients affected by CBS and the total number of patients attending the visual rehabilitation center, multiplied by 100 (%).	From baseline through study completion, up to 24 months.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Generalized Anxiety Disorder-7 (GAD-7). 7 items score.	Scale range: 0 to 21 Interpretation: higher scores indicate a worse outcome (greater severity of anxiety symptoms) Cut-off: greater than 5	3 hours
Change in Patient Health Questionnaire-9 (PHQ-9). 9 Items score	Scale range: 0 to 27 Interpretation: higher scores indicate a worse outcome (greater severity of depressive symptoms) Cut-off: greater than 5	3 hours
Change in Symptom Checklist-90 (SCL-90) . 90 items score	Scale range: 0 to 4 (mean score across items) Interpretation: higher scores indicate a worse outcome (greater psychological distress) Cut-off: greater than 1.5	3 hours
Change in Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). 25 items score	Scale range: 0 to 100 Interpretation: higher scores indicate a better outcome (better visual function and quality of life) Cut-off: less than 60	3 hours
Change in General Self-Efficacy Scale (GSES) score.	Scale range: 10 to 40 Interpretation: higher scores indicate a better outcome (greater perceived self-efficacy) Cut-off: less than 30	3 hours
Change in Perceived Stress Scale (PSS) score.	Scale range: 0 to 40 Interpretation: higher scores indicate a worse outcome (greater perceived stress) Cut-off: less than 15	3 hours

Collaborators and Investigators

• Sponsor: Fondazione Policlinico Universitario Agostino Gemelli IRCCS
• Investigators: Principal Investigator: Stefania Fortini, MD, Fondazione Policlinico Universitario Agostino Gemelli IRCCS

Study record dates

Study Major Dates

• Study Start (Actual): January 15, 2025
• Primary Completion (Estimated): August 31, 2026
• Study Completion (Estimated): January 31, 2027

Study Registration Dates

• First Submitted: December 20, 2024
• First Submitted That Met QC Criteria: April 28, 2026
• First Posted (Actual): May 1, 2026

Study Record Updates

• Last Update Posted (Actual): May 1, 2026
• Last Update Submitted That Met QC Criteria: April 28, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Neurobehavioral Manifestations; Perceptual Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Hallucinations; Charles Bonnet Syndrome
• Other Study ID Numbers: ID 6502

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No