What is the recommended work‑up and management for a patient with visual snow syndrome persisting four years after a COVID‑19 infection?

Visual Snow Syndrome Persisting 4 Years Post-COVID

For a patient with visual snow syndrome (VSS) persisting 4 years after COVID-19, first rule out serious neurological complications (thromboembolic events, encephalitis) through targeted neuroimaging and laboratory testing, then initiate a trial of lamotrigine as first-line pharmacotherapy while simultaneously providing FL-41 tinted lenses and cognitive behavioral therapy. 1, 2, 3, 4

Initial Diagnostic Approach: Rule Out Serious Pathology

This patient meets criteria for persistent long COVID (symptoms >12 weeks post-infection), and VSS represents a rare but documented neurological manifestation. 1, 2 Long COVID is fundamentally a diagnosis of exclusion—you must first eliminate life-threatening conditions before attributing symptoms to post-acute sequelae. 1, 5

Critical Exclusions to Evaluate

• Neurovascular events: Order brain MRI to exclude ischemic stroke, hemorrhagic stroke, or cerebral venous thrombosis, which are recognized PASC complications. 2
• Encephalitis: Assess for focal neurological deficits, fever, altered mental status; obtain CSF analysis if clinical suspicion exists. 1
• Thromboembolic disease: Check D-dimer if respiratory symptoms are present; consider CT angiography if indicated. 1, 5
• Previously overlooked conditions: Screen for malignancy, autoimmune disorders, or metabolic derangements that could manifest with visual disturbances. 1, 5

Baseline Laboratory Panel

Order the following tests as recommended for all long COVID patients: 1, 5

• Complete blood count
• C-reactive protein
• Comprehensive metabolic panel (kidney and liver function)
• Thyroid function tests (TSH, free T4) to exclude thyroiditis
• Fasting glucose and HbA1c if diabetes risk factors present

Neurological Assessment

• Perform cognitive screening tools to document any concurrent "brain fog" (affects 16-26% of long COVID patients). 2
• Obtain orthostatic vital signs (supine and standing heart rate/blood pressure after 5-10 minutes) to screen for postural orthostatic tachycardia syndrome (POTS), which co-occurs in many long COVID patients. 2
• Reserve advanced neuroimaging (functional MRI, PET) for research settings or refractory cases, as these are not standard clinical tools for VSS. 6, 7

Confirming Visual Snow Syndrome Diagnosis

VSS requires the presence of dynamic, continuous tiny dots across the entire visual field persisting >3 months, plus at least two of the following: 3, 6

• Palinopsia (persistence or recurrence of visual images)
• Photopsia (flashes of light)
• Photophobia (light sensitivity)
• Nyctalopia (impaired night vision)

Key clinical pearl: VSS symptoms are subjective and cannot be objectively measured by standard ophthalmologic or neurologic testing—normal eye exams and brain imaging do not exclude the diagnosis. 3, 7, 4

Evidence-Based Treatment Algorithm

First-Line Pharmacotherapy: Lamotrigine

Start lamotrigine as the primary medication, as it has the strongest evidence base among pharmacological treatments for VSS. 3, 4

• Efficacy data: 61.5% of VSS patients showed improvement with lamotrigine in systematic reviews, with 22.2% achieving meaningful response (8/36 patients) including one complete resolution. 3, 4
• Dosing: Begin with 25 mg daily for 2 weeks, then increase by 25-50 mg every 1-2 weeks as tolerated, targeting 100-200 mg daily in divided doses. 4
• Monitoring: Watch for rash (Stevens-Johnson syndrome risk, though rare); counsel patient to report any skin changes immediately.
• Timeline: Allow 8-12 weeks at therapeutic dose before declaring treatment failure.

Alternative Pharmacotherapy if Lamotrigine Fails

If lamotrigine is ineffective or not tolerated after adequate trial: 3, 4

• Benzodiazepines (e.g., clonazepam 0.5-2 mg daily): 71.4% of patients showed improvement in one analysis, but long-term use carries dependence risk—reserve for severe, refractory cases. 3
• Topiramate 25-100 mg daily: 15.4% response rate (2/13 patients), no complete responses reported. 4
• Valproate or propranolol: Sporadic case reports of benefit; consider as third-line options. 4

Medications to AVOID

Do not prescribe amitriptyline or certain antidepressants, as these have been documented to worsen or trigger visual snow symptoms in multiple patients. 3, 7, 4

Non-Pharmacological Interventions (Implement Immediately)

FL-41 Tinted Lenses

Provide prescription for FL-41 (rose-tinted) lenses for daily use, as these consistently provide symptom relief across multiple studies. 3, 7, 4

• These filters target the yellow-blue color spectrum and reduce photophobia and visual disturbances.
• Patients should wear them during all waking hours, including indoors.
• This is a low-risk, high-yield intervention that can be started while titrating medication.

Cognitive Behavioral Therapy

Refer to a psychologist trained in CBT, specifically mindfulness-based cognitive therapy adapted for chronic neurological conditions. 3, 7, 4

• CBT does not eliminate visual snow but helps patients manage distress and functional impairment.
• Combined with tinted lenses, this approach shows the most consistent benefit in recent literature.
• Address concurrent anxiety (present in many long COVID patients) and sleep disturbances (affects 22-44% of PASC patients). 1, 2

Emerging Neuromodulation Approaches

Consider referral to academic centers offering: 7, 8

• Repetitive transcranial magnetic stimulation (rTMS) targeting the lingual gyrus: Early pilot data suggests potential benefit, though evidence remains preliminary.
• Neuro-optometric visual rehabilitation therapy (NORT): Emerging technique with promising anecdotal results but lacking rigorous trials.

Long COVID-Specific Management Considerations

Energy Conservation and Pacing

Implement strict pacing strategies immediately, as this is the foundation of long COVID management per NICE guidelines. 5

• Critical warning: Do NOT recommend exercise or "push through" approaches—75% of long COVID patients with cognitive symptoms worsen with exertion. 2
• Teach the patient to stay within their "energy envelope" and avoid post-exertional symptom exacerbation.

Multidisciplinary Coordination

Establish care coordination with: 2, 5

• Primary care physician as the hub
• Neurology for VSS-specific management
• Ophthalmology to document baseline visual function and rule out ocular pathology
• Psychiatry/psychology for CBT and management of concurrent mood/anxiety symptoms
• Physical medicine and rehabilitation if fatigue or other somatic symptoms are prominent

Address Functional Impact

• Work capacity: Discuss phased return to work with accommodations (reduced screen time, frequent breaks, modified lighting). 5
• Quality of life: 57% of patients with symptoms >12 weeks report decreased QOL—validate the patient's experience and set realistic expectations. 2

Prognosis and Follow-Up

• Natural history: VSS symptoms can persist for years; cognitive impairment and other long COVID manifestations have been documented ≥2 years post-infection. 2
• Treatment expectations: Most interventions only partially alleviate symptoms rather than eliminate them—set realistic goals focused on functional improvement and symptom management. 3, 4
• Monitoring schedule: Reassess every 4-8 weeks during medication titration, then every 3-6 months once stable. Track symptom severity using the Colorado Visual Snow Scale (CVSS) if available. 8

Common Pitfalls to Avoid

• Do not dismiss the patient's symptoms as psychogenic—VSS is a recognized neurological disorder with objective findings on advanced neuroimaging (cortical hyperresponsivity, thalamocortical dysfunction). 6, 7
• Do not order extensive unnecessary testing beyond the initial exclusion workup—VSS has no specific diagnostic marker, and over-investigation wastes resources. 6
• Do not prescribe antidepressants empirically without considering their potential to worsen visual symptoms. 7, 4
• Do not recommend vigorous exercise without first ruling out post-exertional malaise, which is common in long COVID. 2