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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Charles Bonnet Syndrome

Why Does Vision Loss Cause Visual Hallucinations?

At a Glance

Charles Bonnet Syndrome causes people with vision loss to see things that aren't there, like shapes or faces. This is a normal neurological response, not a mental illness, as the brain tries to fill in missing visual input. You can often stop episodes by changing lighting or moving your eyes.

If you are seeing geometric shapes or more complex images as your vision worsens, you are not alone, and it does not mean you are developing a psychiatric condition. This is a common and well-documented experience known as Charles Bonnet Syndrome (CBS) [1][2]. For people with retinitis pigmentosa (RP)—an inherited disease that causes progressive damage to the retina—the brain sometimes reacts to the lack of visual information by creating its own images [3][4]. Nearly one in six patients with inherited retinal diseases experiences these visual hallucinations [5].

A Critical Note on Flashes of Light: While seeing geometric patterns or images is typical of CBS, suddenly seeing new “flashes of light” (photopsias) can be a warning sign of a retinal tear or detachment. If you experience new or increased flashes of light, contact your eye doctor immediately to rule out a serious medical emergency.

Why is My Brain “Filling in the Blanks”?

When your retinas are healthy, they constantly send a stream of visual signals to your brain’s visual cortex. As retinitis pigmentosa damages the retina, this flow of information slows down or stops. In the absence of real visual input, the visual cortex can become overactive or “hyperexcitable” [2][6]. Without real pictures to process, your brain begins to pull from its own memory and imagination, effectively “filling in the blanks” to make up for the missing information [7]. This can result in seeing geometric patterns, or more complex visions like faces, animals, or objects [3][4].

CBS vs. Mental Illness

One of the most frightening parts of experiencing visual hallucinations is the fear of severe psychiatric illness or cognitive decline. It is incredibly important to know that Charles Bonnet Syndrome is not a psychiatric illness, nor is it a sign of dementia [1][8].

The key difference between CBS and psychiatric conditions (or cognitive disorders like Lewy body dementia) is that people with CBS usually know that what they are seeing isn’t real [2][9]. Your logic and cognitive awareness remain completely intact [10][11]. Please do not be afraid to mention these symptoms to your ophthalmologist or neurologist; doctors who treat RP are very familiar with CBS and understand it is a neurological response to vision loss, not a mental health crisis [12][5].

Practical Tips for Managing Episodes

While some medications are occasionally used for severe or highly distressing cases, there is no single standardized medication for Charles Bonnet Syndrome [13][14]. Instead, behavioral strategies are universally the primary approach to managing and sometimes stopping an episode when it happens:

  • Change the lighting: Because hallucinations often happen in dim light or when there isn’t much to look at, turning on a bright light or moving to a different room can give your brain real visual input to process, which may stop the hallucination [15][16].
  • Move your eyes: Rapidly moving your eyes from side to side, or blinking several times, can sometimes interrupt the images [17].
  • Stay active and engaged: Social isolation and a lack of mental stimulation are known triggers for CBS [16][18]. Staying socially active, listening to podcasts, or having a conversation can redirect your brain’s attention [19][15].
  • Acknowledge it and wait: Since the images aren’t dangerous, sometimes simply reminding yourself, “This is just my Charles Bonnet Syndrome,” can reduce anxiety and help you wait for the image to fade [12][20].

Common questions in this guide

What is Charles Bonnet Syndrome?
Charles Bonnet Syndrome is a condition where people with significant vision loss experience visual hallucinations. As the eyes stop sending clear signals to the brain, the visual cortex creates its own images to fill in the missing information.
Are visual hallucinations from vision loss a sign of mental illness?
No, Charles Bonnet Syndrome is not a psychiatric illness or a sign of cognitive decline like dementia. People with this condition usually know that the images they are seeing are not real.
How can I stop a Charles Bonnet Syndrome hallucination?
You can often interrupt an episode by changing the lighting in the room, blinking rapidly, or moving your eyes from side to side. Staying socially active and mentally engaged also helps reduce the frequency of hallucinations.
When should I be worried about seeing flashes of light?
If you suddenly see new or increased flashes of light, this could be a warning sign of a retinal tear or detachment. You should contact your eye doctor immediately to rule out a serious medical emergency.
Are there medications to treat Charles Bonnet Syndrome?
There is no single standardized medication for this condition. While some medications are occasionally used for severe cases, behavioral strategies like changing your environment and redirecting your attention are the primary ways to manage episodes.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.I've started seeing geometric shapes; how can we confirm this is Charles Bonnet Syndrome rather than a retinal issue like a tear or detachment?
  2. 2.Are there specific environmental triggers, like lighting, that I should try modifying to reduce the frequency of these episodes?
  3. 3.Could any of the medications I am currently taking be making these visual hallucinations more frequent or intense?
  4. 4.Can you connect me with support groups or low-vision rehabilitation resources where I can talk to others experiencing Charles Bonnet Syndrome?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

Related questions

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References

References (20)
  1. 1

    Charles Bonnet syndrome versus Occipital Epilepsy, a diagnostic challenge.

    Zhuzhuni H, Nazaret A, Iodice L, et al.

    Acta bio-medica : Atenei Parmensis 2018; (89(2)):262-264 doi:10.23750/abm.v89i2.6250.

    PMID: 29957762
  2. 2

    Think sight loss, think Charles Bonnet syndrome.

    Best J, Liu PY, Ffytche D, et al.

    Therapeutic advances in ophthalmology 2019; (11()):2515841419895909 doi:10.1177/2515841419895909.

    PMID: 31903448
  3. 3

    Charles Bonnet Syndrome in the Setting of a Traumatic Brain Injury.

    Irizarry R, Sosa Gomez A, Tamayo Acosta J, Gonzalez Diaz L

    Cureus 2022; (14(9)):e29293 doi:10.7759/cureus.29293.

    PMID: 36147864
  4. 4

    Epidemiology and phenomenology of the Charles Bonnet syndrome in low-vision patients.

    Christoph SEG, Boden KT, Pütz A, et al.

    International ophthalmology 2024; (44(1)):375 doi:10.1007/s10792-024-03298-0.

    PMID: 39256212
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    Charles Bonnet syndrome in adults with inherited retinal disease: prevalence and patient perspectives.

    Weatherby TJM, Boyle M, Madhusudhan S

    BMJ open ophthalmology 2025; (10(1)) doi:10.1136/bmjophth-2024-002104.

    PMID: 40588359
  6. 6

    Resting-state functional connectivity and cortical thickness characterization of a patient with Charles Bonnet syndrome.

    Martial C, Larroque SK, Cavaliere C, et al.

    PloS one 2019; (14(7)):e0219656 doi:10.1371/journal.pone.0219656.

    PMID: 31318888
  7. 7

    Power spectral density and coherence analysis of eye disease with and without visual hallucination.

    Yildiz S, Yulug B, Kocabora MS, Hanoglu L

    Neuroscience letters 2021; (740()):135444 doi:10.1016/j.neulet.2020.135444.

    PMID: 33127444
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    [Complex visual hallucinations in the visually impaired, the Charles Bonnet syndrome].

    Molander S, Singh A

    Lakartidningen 2019; (116()).

    PMID: 30667516
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    The elephant in the room: understanding the pathogenesis of Charles Bonnet syndrome.

    Carpenter K, Jolly JK, Bridge H

    Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) 2019; (39(6)):414-421 doi:10.1111/opo.12645.

    PMID: 31591762
  10. 10

    Evaluation of the Clinical Features, Management, and Prognoses of Patients With Charles Bonnet Syndrome.

    Buyukgol H, Ilik F, Ertem DH

    The Journal of nervous and mental disease 2019; (207(12)):1045-1047 doi:10.1097/NMD.0000000000001101.

    PMID: 31703034
  11. 11

    Is Charles Bonnet Syndrome a Harbinger of Neurocognitive Disorder With Lewy Bodies? A Clinical Conundrum.

    Kumari S, Nath S, Narasimha VL

    Journal of psychiatric practice 2025; (31(1)):49-52 doi:10.1097/PRA.0000000000000828.

    PMID: 39836683
  12. 12

    Addressing chronic visual hallucination by multimodal retinal imaging: a CBS case.

    O'Neill Y, Arrigo A, Stanga PE

    Therapeutic advances in ophthalmology 2025; (17()):25158414251320032 doi:10.1177/25158414251320032.

    PMID: 40655237
  13. 13

    A Case Report on Charles Bonnet Syndrome.

    Maruzairi H, Joo CL

    Iranian journal of psychiatry 2022; (17(2)):240-242 doi:10.18502/ijps.v17i2.8914.

    PMID: 36262761
  14. 14

    A Case Report and Review: Charles Bonnet Syndrome Plus With Dementia.

    Kompella S, Kaushal S, Khan SA, Alvarez Villalba CL

    HCA healthcare journal of medicine 2022; (3(1)):23-28 doi:10.36518/2689-0216.1303.

    PMID: 37426870
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    'They're creepy creatures with human-like features': children's experiences of visual hallucinations in Charles Bonnet syndrome-a qualitative study.

    Jones L, Ditzel-Finn L, McDonald L, Moosajee M

    Archives of disease in childhood 2025; (110(5)):384-390 doi:10.1136/archdischild-2024-327811.

    PMID: 39788624
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    Social Isolation as a Precipitating Factor for Charles Bonnet Syndrome in a Patient with Mild Visual Deterioration.

    Bhat SP, Shipchandler A, Tokunaga C

    Reports (MDPI) 2024; (7(3)) doi:10.3390/reports7030065.

    PMID: 40729288
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    Charles Bonnet syndrome and periodic alternating nystagmus: Moving visual hallucinations.

    Minakaran N, Soorma T, Bronstein AM, Plant GT

    Neurology 2019; (92(10)):e1072-e1075 doi:10.1212/WNL.0000000000007033.

    PMID: 30700594
  18. 18

    Charles Bonnet syndrome in patients with Stargardt disease: prevalence and risk factors.

    Dhooge PPA, Teunisse RJ, Liefers B, et al.

    The British journal of ophthalmology 2023; (107(2)):248-253 doi:10.1136/bjophthalmol-2021-319525.

    PMID: 34348923
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    Podcast-driven insights into Charles Bonnet Syndrome: Impact on self-management strategies and communication.

    Higgins BE, Taylor DJ, Dave S, et al.

    Digital health 2025; (11()):20552076251382830 doi:10.1177/20552076251382830.

    PMID: 41268190
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    Emotional well-being in Charles Bonnet syndrome: exploring associations with negative affect, loneliness and quality of life.

    Higgins B, Taylor D, Crabb D, Callaghan T

    Therapeutic advances in ophthalmology 2024; (16()):25158414241275444 doi:10.1177/25158414241275444.

    PMID: 39351142

This page provides educational information about Charles Bonnet Syndrome and vision loss. It is not a substitute for professional medical advice; always report new visual symptoms, especially flashes of light, to your eye doctor immediately.

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