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Charles Bonnet Syndrome: Why a Person With Vision Loss Sees Things That Aren't There

Charles Bonnet Syndrome (CBS) is when someone with significant vision loss sees vivid, detailed images—people, animals, patterns, or buildings—that aren't actually present, while usually knowing the visions aren't real. It is not mental illness or dementia; it's the brain's response to losing visual input, and there are gentle, concrete steps to confirm what's happening and ease any distress.

Key points

  • CBS causes complex visual hallucinations in people with vision loss, and the person usually knows they aren't real (intact insight).
  • CBS is not mental illness or dementia—it's a neurological response to lack of visual input, similar to a phantom limb.
  • The hallucinations are exclusively visual—no voices, smells, or other senses—which is a major diagnostic clue.
  • Diagnosis means ruling out other causes: infection, dehydration, medication side effects, delirium, stroke, and dementia—especially Lewy body disease.
  • First steps that help most: a thorough eye exam, a medical workup, and a hallucination diary.
  • Management centers on reassurance, distraction, and environmental changes—not medication.
  • Hallucinations are more common in dim light; bright, even lighting often reduces episodes.
  • Always check for a medical cause when hallucinations are new or sudden.
  • If non-drug approaches fail and distress is high, discuss medication options only with a clinician who understands CBS.

Understanding the situation

Charles Bonnet Syndrome, also called 'visual release hallucinations,' occurs when partial or complete vision loss reduces the signals reaching the brain's visual cortex. Under-stimulated, the visual brain becomes 'disinhibited' and begins generating its own images from stored memory—much like a phantom limb sensation or a dream that happens while awake. The hallmark of CBS is that the experiences are purely visual (no voices, smells, or other senses) and the person generally retains 'intact insight'—they recognize the images aren't real. This insight is the key feature separating CBS from hallucinations of dementia or psychosis, where insight is typically lost. The syndrome was first described in the 1700s by naturalist Charles Bonnet, who recorded his grandfather seeing people, birds, and buildings after losing sight to cataracts. CBS is commonly underdiagnosed or misdiagnosed because people fear being labeled 'crazy' and many clinicians aren't familiar with it—so the visions get mistaken for early Alzheimer's, Lewy body dementia, or schizophrenia. That distinction matters greatly: antipsychotics used for psychosis can actually worsen CBS and cause harmful side effects in older adults. Hallucinations in Lewy body dementia can look similar (small animals, children, strangers, a 'sense of presence,' or fleeting peripheral 'passage' figures), but LBD typically brings loss of insight over time plus cognitive fluctuations, REM sleep behavior disorder, and movement problems. In CBS, thinking and memory stay intact and the scenes are often complex and well-formed. Importantly, CBS and early dementia can co-exist, which is why a careful evaluation by a knowledgeable clinician—and time—is essential.

General caregiving information, not medical advice. Check medications and major care changes with your clinician.

Step-by-step

  1. Stay calm and speak gently—your reaction sets the emotional tone for the whole moment.

  2. Acknowledge what they see and check insight without confrontation: ask 'Do you think she's really there?' If they recognize it isn't real, reassure them that 'the brain can play tricks when the eyes aren't working well.'

  3. Keep a hallucination diary for at least two weeks: note date, time, what was seen, duration, lighting, activity, emotional reaction, and what helped—then bring it to appointments.

  4. Improve the environment in the moment: turn on bright, even lighting and use nightlights to erase shadows, since low light triggers episodes.

  5. Try non-drug visual techniques: have the person look directly at the image and blink, move the eyes side to side, or shift their gaze to a familiar real object.

  6. Redirect with a simple activity—offer water, walk to another room, fold laundry, or look at a familiar photo together.

  7. Reduce visual clutter using solid colors, simple consistent furniture, and removing busy patterns and unexpected mirrors.

  8. Schedule a comprehensive eye exam (optometrist or ophthalmologist) to assess macular degeneration, glaucoma, cataracts, or diabetic retinopathy.

  9. See a primary care provider or neurologist for a medical workup to rule out other causes of new hallucinations—UTI, dehydration, electrolyte imbalance, medication side effects, delirium, or cognitive decline.

  10. Name the condition explicitly at the visit: 'I've read that vision loss can cause the brain to fill in images—could this be Charles Bonnet Syndrome?'

  11. For sudden or new hallucinations accompanied by confusion, fever, or agitation, treat it as possible delirium/infection and seek prompt medical evaluation.

  12. If visions stay frequent or upsetting after non-drug strategies, ask for a referral to a low-vision specialist, neuro-ophthalmologist, or geriatric psychiatrist.

  13. Once CBS is confirmed, provide education and reassurance—explain it's a known brain quirk, not insanity or dementia—and connect with vision-loss support groups such as the American Council of the Blind.

  14. Pause driving, cooking, and other high-risk activities during active hallucinations and reassess safety with the doctor.

What not to do

  • Don't argue, laugh at, dismiss, or insist the visions aren't real—this erodes trust and increases distress.

  • Don't say a blunt 'It's not real'; validate the experience first, then gently explain the brain trick.

  • Don't jump to a dementia or psychiatric diagnosis—but also don't assume it's CBS just because vision loss exists; rule out delirium, infection, and Lewy body dementia.

  • Don't ignore or write off hallucinations as 'just old age'—a medical evaluation is needed to catch treatable causes.

  • Don't start antipsychotics or anti-anxiety medications without a clear diagnosis; they can worsen CBS, worsen Lewy body symptoms, cause sedation, and raise fall risk.

  • Don't ignore sudden changes—new or worsening hallucinations with confusion, fever, or agitation warrant prompt medical attention.

  • Don't assume every hallucination is frightening—ask how it makes the person feel before intervening.

  • Don't isolate the person or strip away routines; boredom and low stimulation can increase episodes.

Practical tools

  • Hallucination Diary / Log Template

    Keep a notebook or phone app with columns for Date, Time, What Was Seen, Duration, Lighting, Activity, Emotional Reaction, and What Helped. Track for at least two weeks to spot triggers, and bring it to every appointment as concrete data.

  • Look and Blink Technique

    Teach the person to look directly at the hallucination and blink rapidly. If that doesn't dissolve it, have them move their eyes side to side or shift gaze to another object.

  • Look and Shift Technique

    Have the person look at the hallucination, then quickly shift their gaze to a real fixed object such as a clock or plant. Practice during calm moments—this can help the visual brain 'reset' and the image fade.

  • Lighting Adjustment Checklist

    (1) Add nightlights in hallways and bathrooms; (2) use bright, even, full-spectrum daylight bulbs in main rooms; (3) eliminate dark corners and shadows; (4) cut glare with blinds and close curtains at dusk; (5) boost evening room brightness; (6) consider a dawn-simulator alarm clock; (7) avoid patterned wallpaper and busy decor.

  • Reassurance Script for Caregivers

    Say: 'I know you're seeing something that feels real. It's not dangerous—it's your brain playing a trick because your eyes aren't sending clear pictures. It will pass. Let's take a breath together.' Never lead with a flat 'It's not real.'

  • The 'Brain Trick' Explanation

    Normalize the experience: 'When our eyes don't work well, the brain tries to fill in the missing pictures—like a dream while you're awake. It's not real, but it can feel that way.' (Note: skip this with people who have lost insight, such as in Lewy body dementia or advanced Alzheimer's.)

  • Environmental Simplification Guide (E00605)

    Use solid-color bedding and curtains, remove busy patterns, keep furniture consistent and in familiar spots, avoid mirrors in unexpected places, and use contrasting colors for doors and light switches to reduce visual confusion that can trigger images.

  • CBS Information Card (E00605)

    Print a small wallet card that reads: 'I have Charles Bonnet Syndrome. I see vivid images that aren't real due to vision loss. I know they aren't real. This is not dementia or psychosis.' Carry it for ER visits, new doctors, and skeptical relatives.

  • Doctor Visit Prep Sheet

    Bring a one-line vision-loss summary, the hallucination diary, a complete medication list (including OTC and supplements), and key questions—e.g., 'Is CBS being considered?', 'Should we screen cognition?', 'Is a neuro-ophthalmology or low-vision referral appropriate?'

Reassurance is the most powerful tool—simply knowing CBS is a recognized, explainable brain response, not insanity or dementia, brings many people huge relief.

Brighten the room before you do anything else; many episodes fade with more, more even light.

Ask how the vision makes them feel before intervening—not every image is frightening, and some find them curious or even pleasant.

Boredom and low stimulation can fuel hallucinations, so keep routines, conversation, music, or audiobooks going.

Bring your diary and medication list to appointments—concrete patterns help a busy clinician reach the right diagnosis faster.

Remember CBS and early dementia can co-exist; intact insight strongly suggests CBS, but a thorough evaluation is still worthwhile.

Discuss with your clinician

Ask directly: 'Could these visual hallucinations be Charles Bonnet Syndrome rather than dementia or psychosis, and what tests can help confirm it?' Also ask: 'What tests can rule out infection, dehydration, medication side effects, or stroke?'

'Should we review all prescriptions, OTC drugs, and supplements that might contribute?'

'Is it safe to try non-medication strategies first, and if medication is later needed, what are the safest options and risks for an older adult with vision loss?'

'Can you refer us to a low-vision specialist, neuro-ophthalmologist, or geriatric psychiatrist?'

and—if there are cognitive concerns too—'How do we tell CBS from Lewy body dementia or both, and would a brain scan or DaTscan help?' Finally, clarify follow-up: 'How often should we check in, and what changes should prompt an urgent call?' Never treat medication names as instructions—confirm any drug decision with the clinician.

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