Distinguishing Retinal Arteritis from Phlebitis

Clinical Findings

Arterial narrowing or "boxcarring" (segmental blood column interruption) and retinal emboli within arterioles are findings suggestive of arteritis, according to the American Academy of Ophthalmology 1
Venous tortuosity and dilation are findings suggestive of phlebitis, as noted by the American Academy of Ophthalmology 2

Areas of capillary nonperfusion are seen in arteritis-specific angiographic findings, as reported by the American Academy of Ophthalmology 1
Delayed venous drainage and venous beading patterns are seen in phlebitis-specific angiographic findings, according to the American Academy of Ophthalmology 2
Cystoid macular edema is more common in phlebitis, as noted by the American Academy of Ophthalmology 3

If a patient over 50 years old is suspected to have arteritis, immediate ESR and CRP tests should be obtained before any imaging, as giant cell arteritis requires urgent high-dose corticosteroids, as recommended by the American College of Rheumatology 1
Age >50 years with acute vision loss, headache, scalp tenderness, or jaw claudication are red flags requiring immediate workup for giant cell arteritis, according to the American College of Rheumatology 1
Relative afferent pupillary defect is a significant finding in patients with suspected arteritis, as reported by the American Academy of Ophthalmology 1, 3

Step 1: Perform slit-lamp biomicroscopy with dilated fundus examination to document vascular caliber changes, hemorrhage patterns, and cotton-wool spots, as recommended by the American Academy of Ophthalmology 1, 3
Step 3: Use OCT as adjunctive imaging to detect macular edema and document vitreoretinal interface changes, according to the American Academy of Ophthalmology 3
Gonioscopy should not be forgotten, as neovascularization of the iris or angle can occur with severe ischemia from either arteritis or phlebitis, as noted by the American Academy of Ophthalmology 1, 3

Retinal arteritis and phlebitis are differentiated primarily by fluorescein angiography findings, with arteritis showing delayed arterial filling, arterial wall staining, and segmental arterial occlusion, while phlebitis demonstrates venous wall staining, perivenular hemorrhages, and irregular venous caliber with dilated segments, according to the American Academy of Ophthalmology 4
Cotton-wool spots indicate focal ischemia in retinal arteritis, as reported in Ophthalmology 5

Fluorescein angiography is the confirmatory diagnostic test that definitively distinguishes arteritis from phlebitis, as stated by the American Academy of Ophthalmology 4, 6
Delayed retinal arterial filling in early phases is a characteristic finding in arteritis on fluorescein angiography, according to Ophthalmology 5

Optical coherence tomography (OCT) detects macular edema, common in phlebitis, and shows inner retinal thickening and hyperreflectivity in acute arterial occlusion, as reported by the American Academy of Ophthalmology 4, 5, 7, 8
Fundus photography documents vascular sheathing patterns and caliber changes, and tracks hemorrhage distribution and disease progression over time, according to the American Academy of Ophthalmology 4, 6

Giant cell arteritis requires immediate high-dose corticosteroids before biopsy, as recommended by the American Heart Association 9
The American Academy of Ophthalmology recommends obtaining ESR and CRP urgently if giant cell arteritis is suspected 4