Charles Bonnet Syndrome in Low Vision Patients (CBS)

April 28, 2026 updated by: Fondazione Policlinico Universitario Agostino Gemelli IRCCS

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

Status

Indicates the current recruitment status or the expanded access status.
Enrolling by invitation

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
640

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

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

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Prevalence of the Charles Bonnet Syndrome
Time Frame: From baseline through study completion, up to 24 months.
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in Generalized Anxiety Disorder-7 (GAD-7). 7 items score.
Time Frame: 3 hours
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
Time Frame: 3 hours
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
Time Frame: 3 hours
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
Time Frame: 3 hours
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.
Time Frame: 3 hours
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.
Time Frame: 3 hours
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

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Fondazione Policlinico Universitario Agostino Gemelli IRCCS

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Stefania Fortini, MD, Fondazione Policlinico Universitario Agostino Gemelli IRCCS

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 15, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 31, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 31, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 20, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 28, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 1, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 1, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 28, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
December 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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