Arteritic vs Non-Arteritic CRAO: Complete Differentiation

Overview

1. Non-arteritic (NA-CRAO) - >90% of all cases; embolic or thrombotic in origin
2. Arteritic (A-CRAO) - caused by Giant Cell Arteritis (GCA/temporal arteritis); ~5-10% of cases; a sight-threatening and life-threatening emergency

Clinical Differentiation

Systemic Features

Kanski's Clinical Ophthalmology: "Sudden profound loss of vision, painless except in GCA" - the presence of pain is the single most important clinical differentiator.

Fundus Examination Differences

Non-Arteritic CRAO

Non-arteritic CRAO - classic cherry-red spot with surrounding milky-white retinal edema (Wills Eye Manual)

Non-arteritic CRAO with cilioretinal artery sparing - note island of preserved orange macular tissue (Kanski's Clinical Ophthalmology)

• Cherry-red spot at the fovea (hallmark) - the orange choroidal reflex shows through the thin, avascular foveola against the surrounding pale edematous retina
• Diffuse milky-white retinal edema in the posterior pole
• Attenuated retinal arterioles with "boxcarring" or "cattle trucking" (segmentation of blood column)
• Emboli visible in ~20% - at arteriolar bifurcations (Hollenhorst cholesterol plaques = refractile yellow; calcium = white; platelet-fibrin = dull white)
• Cilioretinal artery sparing - if present, an island of normal-colored retina at the macula preserves some central vision
• Occasional small hemorrhage
• Disc may appear normal initially; peripapillary retina especially swollen

Arteritic CRAO (GCA)

• No cherry-red spot (or less prominent cherry-red spot) - this is the key fundus differentiator
• If the ophthalmic artery is also involved (common in GCA), the entire retina including the foveola is white/chalky, obliterating the cherry-red appearance
• VA = no light perception - absence of any light perception strongly points to GCA or ophthalmic artery occlusion
• The disc may show ischemic pallor/swelling (concurrent arteritic AION is common in GCA)
• Choroidal involvement: GCA typically involves the posterior ciliary arteries too, so you may see choroidal ischemia (triangular/geographic pale areas) alongside retinal whitening
• No visible emboli (it is a vasculitis/inflammation of the vessel wall, not embolic)

Kanski Fig 13.40D - CRAO with cilioretinal artery sparing, showing the preserved orange island at the fovea

Combined cilioretinal artery occlusion + AION (disc swelling, disc hemorrhages, peripapillary whitening) - classic arteritic/GCA pattern (Kanski Fig 13.41)

FFA (Fluorescein Angiography) Differences

Both Types Share These General CRAO FFA Features

• Delayed or absent arterial filling (prolonged arteriovenous transit time)
• Hypofluorescence of the posterior pole from masking of choroidal fluorescence by edematous/opaque retina
• Slow, stuttering arterial filling with "pruning" of arterioles
• In recovery phase: arteriovenous shunting or re-canalization

Non-Arteritic CRAO - FFA

Arteritic CRAO (GCA) - FFA

Summary Comparison Table

Treatment

Non-Arteritic CRAO

1. Ocular massage with fundus contact lens or digital massage (firm pressure for 10-15 sec, release) - to dislodge emboli
2. Anterior chamber paracentesis - to rapidly lower IOP and increase perfusion pressure
3. IOP lowering - acetazolamide 500 mg IV/PO; topical beta-blocker (timolol 0.5%)
4. IV alteplase (tPA) - 0.9 mg/kg (10% over 1 min, remainder over 59 min); consider within 4.5 hours of onset; treat as acute ischemic stroke
   • Intra-arterial thrombolysis (ophthalmic artery) - may have benefit within 6 hours; evidence remains heterogeneous
5. Rebreathing CO2 (5% CO2 / 95% O2 carbogen) - vasodilatory; largely anecdotal
6. Nd:YAG embolysis - if visible embolus; variable success; risk of vitreous/subretinal hemorrhage
7. Refer immediately to stroke center (AAO 2018 guidelines)

• CBC, fasting glucose, HbA1c, lipid profile, PT/PTT
• Carotid Doppler (30% have severe carotid disease)
• ECG + echocardiography (cardiac embolism workup)
• In patients <50 years: hypercoagulable screen (ANA, antiphospholipid Ab, protein C/S, factor V Leiden, homocysteine, SPEP)
• ESR/CRP/platelets if age ≥55 (to rule out GCA)

• Ophthalmic review at 3-4 weeks, then monthly for 2 more months
• Monitor for rubeosis iridis (up to 1 in 5 eyes, usually at 4-5 weeks) and NVD/NVE (~2%) - treat with PRP and/or anti-VEGF if neovascularization develops

Arteritic CRAO (GCA) - Emergency

1. Immediate high-dose IV corticosteroids - methylprednisolone 500 mg-1 g IV daily for 3 days, then transition to oral prednisolone 1 mg/kg/day
   • Do NOT wait for temporal artery biopsy results before starting steroids
   • Biopsy should be performed within 1-2 weeks (steroid effect on biopsy is minimal in the first 2 weeks)
2. Goal: Prevent fellow eye involvement (bilateral blindness risk >50% if untreated)
3. Aspirin (low-dose) may be added for its anti-platelet/anti-inflammatory effect
4. NO thrombolytics - not indicated; the mechanism is vasculitis, not thromboembolism
5. Tocilizumab (IL-6 inhibitor) - now used for long-term GCA management/steroid-sparing
6. Urgent rheumatology referral
7. Temporal artery biopsy as soon as logistically possible (same side as symptoms)

Kanski's Clinical Ophthalmology (10e) - Key clinical pearl: "Absence of light perception usually indicates either GCA or ophthalmic artery occlusion." This sign should trigger immediate ESR/CRP and steroids.

Wills Eye Manual: "If GCA suspected, start high-dose systemic steroids immediately. Immediate ESR, CRP, and platelets in all patients ≥55 years with no visible embolus."

Quick Clinical Algorithm

Sudden profound painless monocular vision loss
              ↓
        Age ≥55 years?
         ↓          ↓
        YES          NO → Non-arteritic workup → Stroke center
         ↓
Check ESR/CRP/Plt + query GCA symptoms
         ↓
Cherry-red spot present? Embolus visible?
Choroid looks normal? → NON-ARTERITIC
         ↓
No cherry-red spot? NLP? Disc swollen?
Headache/jaw claudication? ESR elevated? → ARTERITIC GCA
         ↓
Immediate IV methylprednisolone (do not wait for biopsy)