What is the appropriate work‑up and differential diagnosis for a woman with new floaters, photopsia, and light‑headedness after ophthalmologic evaluation has excluded primary ocular pathology?

Workup and Differential Diagnosis for Floaters, Flashes, and Lightheadedness After Negative Ophthalmologic Evaluation

After ophthalmology has excluded primary ocular pathology, the most critical next step is urgent evaluation for giant cell arteritis (GCA) in patients over 50 years, as this represents a vision-threatening and life-threatening emergency requiring immediate high-dose corticosteroids to prevent bilateral blindness. 1

Immediate Priority: Rule Out Giant Cell Arteritis

When to Suspect GCA

• All patients over 50 years with new visual symptoms (floaters, photopsias) require urgent GCA evaluation, even without classic symptoms 1, 2
• The combination of visual symptoms plus lightheadedness may represent cerebral ischemia from large vessel vasculitis 1

Essential Laboratory Testing

• ESR and CRP must be obtained immediately in all patients over 50 years 1, 2
• ESR >60 mm/h has high likelihood ratio for GCA diagnosis 2
• Do not wait for laboratory results to initiate treatment if clinical suspicion is high 1

Key Clinical Features to Assess

• Jaw claudication (most specific symptom for GCA) 2
• Scalp tenderness, temporal artery tenderness 2
• New-onset persistent headache, often temporal 1
• Constitutional symptoms: weight loss >2 kg, low-grade fever, fatigue, night sweats 1
• Symptoms of polymyalgia rheumatica 1

Urgent Management Protocol

• If GCA is suspected, start high-dose corticosteroids immediately before diagnostic confirmation to prevent contralateral eye involvement 1, 2
• Refer urgently to specialist team with access to temporal artery biopsy and imaging within 24 hours 1
• Delaying treatment when visual symptoms are present is the strongest risk factor for permanent blindness 1

Secondary Priority: Neurologic and Vascular Evaluation

Cerebrovascular Assessment

• Lightheadedness combined with visual symptoms warrants evaluation for cerebral ischemia 1
• Brain MRI with diffusion-weighted imaging identifies concurrent stroke in up to 24% of retinal vascular events 2
• Vascular imaging (CTA or MRA) assesses for carotid stenosis, which is present in up to 70% of patients with retinal artery occlusion 2

Cardiovascular Risk Stratification

• Assess for risk factors: hypertension, diabetes, hyperlipidemia, smoking, coronary heart disease 1, 2
• Consider cardiac monitoring if vascular etiology suspected 2
• Up to 25% of patients with retinal artery occlusion have concurrent silent brain infarction 2

Differential Diagnosis Framework

Vascular/Inflammatory Causes (Highest Priority)

• Giant cell arteritis - most critical diagnosis not to miss in patients >50 years 1, 2
• Takayasu arteritis - younger patients with constitutional symptoms and vascular claudication 1
• Retinal artery occlusion (central or branch) - stroke equivalent requiring emergency evaluation 2
• Carotid-cavernous fistula - may present with visual symptoms and orbital congestion 1

Posterior Vitreous Detachment Complications

• Even with negative initial ophthalmologic exam, 2-5% of patients develop retinal breaks within 6 weeks 3, 4
• Trauma-induced PVD can occur at younger age than typical age-related PVD 3
• Mandatory follow-up within 6 weeks even if initial examination was normal 3, 4

Systemic Causes of Lightheadedness

• Orthostatic hypotension
• Cardiac arrhythmias
• Anemia
• Medication effects (especially if patient started on new medications)

Neurologic Causes

• Vertebrobasilar insufficiency - can cause both visual symptoms and lightheadedness
• Migraine with aura - photopsias may occur without headache
• Demyelinating disease (multiple sclerosis, neuromyelitis optica) - requires MRI brain and orbits with contrast 2

Specific Workup Algorithm

Step 1: Age-Based Risk Stratification

• If age ≥50 years: ESR, CRP immediately; consider empiric corticosteroids if high suspicion 1, 2
• If age <50 years: Proceed to cardiovascular and neurologic evaluation

Step 2: Laboratory Evaluation

• ESR, CRP (mandatory in all patients ≥50 years) 1, 2
• Complete blood count (assess for anemia, thrombocytopenia)
• Comprehensive metabolic panel
• Lipid panel, hemoglobin A1c (cardiovascular risk assessment) 2

Step 3: Imaging Studies

• Brain MRI with diffusion-weighted imaging - identifies stroke, demyelinating lesions 2
• Vascular imaging (CTA or MRA) - assesses carotid stenosis, vertebrobasilar system 2
• Consider temporal artery ultrasound or MRI if GCA suspected 1

Step 4: Cardiovascular Evaluation

• ECG (assess for arrhythmias)
• Orthostatic vital signs
• Consider echocardiogram if embolic source suspected 2
• 24-hour Holter monitor if paroxysmal arrhythmia suspected

Step 5: Ophthalmologic Re-evaluation

• Return to ophthalmology within 6 weeks even if initial exam was normal 3, 4
• Patient must be instructed to return immediately if symptoms worsen or new symptoms develop (increased floaters, peripheral field loss, decreased acuity) 3, 4

Critical Pitfalls to Avoid

Do Not Delay GCA Treatment

• Never wait for biopsy or imaging results to start corticosteroids in suspected GCA with visual symptoms 1
• Imaging and biopsy can show GCA features even weeks after corticosteroid initiation 1

Do Not Assume Negative Ophthalmology Exam is Definitive

• 8-22% of patients with acute PVD symptoms have retinal tear at initial examination 3, 4
• Additional 2-5% develop breaks in following 6 weeks 3, 4
• At least 50% of untreated symptomatic retinal breaks progress to detachment 4

Do Not Dismiss Lightheadedness as Benign

• Combination of visual symptoms and lightheadedness may indicate cerebral ischemia 1
• Stroke risk remains highest in first 7 days even if vision improves 2

Do Not Overlook Atypical Presentations

• GCA can present without classic symptoms - maintain high index of suspicion in all patients >50 years with new visual symptoms 1, 2
• Constitutional symptoms may be subtle or absent 1

Patient Education and Safety Netting

Warning Signs Requiring Immediate Return

• New or increased floaters 3, 4
• New flashes of light 3, 4
• Peripheral visual field loss 3, 4
• Decreased visual acuity 3, 4
• Worsening lightheadedness or new neurologic symptoms 1

Follow-up Timeline

• Ophthalmology re-examination within 6 weeks mandatory 3, 4
• If GCA suspected: specialist evaluation within 24 hours 1
• If vascular cause identified: stroke neurology follow-up within 7 days 2