Patient with right posterior cerebral artery occipital stroke causing permanent left visual‑field loss and ongoing vivid visual hallucinations—could this be ocular migraine or Charles Bonnet syndrome, and how should it be evaluated and managed?

This is Charles Bonnet Syndrome, Not Ocular Migraine

The neurologist's attribution to "ocular migraine" is incorrect—this patient has Charles Bonnet syndrome (CBS) secondary to right posterior cerebral artery occipital stroke causing permanent left visual field loss. 1, 2, 3

Why This is CBS and Not Ocular Migraine

Ocular migraine causes transient, reversible visual phenomena (scintillations, scotomas) lasting minutes to hours, not permanent visual field defects with persistent complex hallucinations. 3, 4 The key distinguishing features in this case are:

• Permanent structural damage: Right PCA occipital stroke with persistent left visual field loss 3, 4
• Complex, vivid hallucinations: CBS characteristically produces organized, well-defined visual images in the area of visual field loss 1, 2, 3
• Preserved insight: The patient recognizes hallucinations are unreal, a cardinal CBS feature 1, 2
• Post-stroke timing: CBS can develop following occipital lobe infarction as a cortical release phenomenon 3, 4

Diagnostic Confirmation Required

Obtain formal automated perimetry to precisely document the left homonymous hemianopia and confirm it matches the anatomic stroke location. 5, 1

Verify all four diagnostic criteria for CBS are met:

• Recurrent, vivid visual hallucinations 1, 2
• Preserved insight that images are unreal 1, 2
• No alternative neurological/psychiatric explanation 1, 2
• Documented vision loss (left visual field deficit) 1, 2

Screen for red-flag features that would require alternative diagnosis:

• Lack of insight despite education about CBS 1, 6
• Interactive hallucinations that respond to the patient 1, 6
• New neurological signs beyond the original stroke deficits 1, 6
• Cognitive decline or behavioral changes suggesting dementia with Lewy bodies or Parkinson's disease 1, 6

Perform comprehensive medication review to exclude drugs provoking hallucinations: anticholinergics, systemic corticosteroids, dopaminergic agents, other psychoactive medications. 1, 6

Screen for depression and anxiety using validated tools, as vision loss significantly increases mental health risk. 1, 6

Management Algorithm

First-Line: Education and Reassurance (Therapeutic in Itself)

Educate the patient and family that CBS is a benign cortical release phenomenon affecting 15-60% of visually impaired patients—this discussion alone provides significant symptom relief. 1, 2 Emphasize:

• Hallucinations result from the brain's visual cortex generating images due to lack of normal visual input from the damaged occipital lobe 2, 7
• CBS does not indicate mental illness or psychiatric disease 2, 8
• The condition is common and expected with this type of stroke-related vision loss 1, 2

Second-Line: Non-Pharmacological Self-Management

Teach specific techniques that may reduce hallucination frequency:

• Rapid eye movements or saccades 1, 2
• Changing lighting conditions (increasing or decreasing ambient light) 1, 2
• Distraction strategies: conversation, music, tactile stimulation 1

Vision Rehabilitation Referral (Strongly Recommended)

Refer to comprehensive vision rehabilitation services to optimize residual vision and provide psychological support—moderate-quality evidence shows improvement in vision-related quality of life and depression. 1 This should address:

• Maximizing remaining vision through lighting modifications, magnification, contrast enhancement 1
• Preventing social isolation and depression 1
• Peer support groups where patients discuss experiences 1

Pharmacological Treatment (Reserved for Severe, Refractory Cases Only)

Do NOT prescribe medications as first-line—no robust evidence supports efficacy of any pharmacological agent for typical CBS. 1, 6

Consider atypical antipsychotics (risperidone, olanzapine, quetiapine) ONLY if:

• Severe distress persists despite education and non-pharmacological measures 1, 6
• Hallucinations significantly impair daily function 6
• Patient specifically requests pharmacological intervention 1

Note: Evidence for antipsychotics is limited to anecdotal case reports and small series—use cautiously with informed consent about limited efficacy data. 1, 6

Follow-Up and Monitoring

Schedule ongoing ophthalmology follow-up to monitor visual function and reinforce support measures. 1

Reassess for depression and anxiety at each visit using standardized screening tools; refer for formal psychiatric evaluation if severe mood changes, interference with daily life, or suicidal ideation emerge. 1, 6

Monitor for atypical evolution that would suggest alternative diagnosis: loss of insight, interactive hallucinations, new neurological signs, or progression to psychotic symptoms. 1, 6, 9

Common Pitfalls to Avoid

Do not dismiss this as "just migraine"—the permanent structural damage and persistent hallucinations are incompatible with ocular migraine. 3, 4

Do not reflexively prescribe antipsychotics—typical CBS patients maintain insight and hallucinations are benign; education is therapeutic. 1, 6

Do not overlook the psychological impact of permanent vision loss itself, which requires addressing through rehabilitation and support services beyond just managing hallucinations. 1

Do not fail to document that this is a recognized stroke complication—CBS following occipital lobe infarction is well-described and represents cortical deafferentation, not a separate disease process. 3, 4