Central Retinal Vein Occlusion: Pathogenesis and clinical findings
Authors: Graeme Prosperi-Porta Mina Mina Reviewers: Stephanie Cote Usama Malik Mao Ding Johnathan Wong* *MD at time of publication
Hypercoagulable state
(pathologic state where there is an exaggerated tendency for the blood to clot)
↓ Anticoagulation (e.g., Protein C or S def) and/or ↑ coagulation (e.g., malignancy, Polycythemia Vera)
Non-ischemic (perfused) CRVO
Glaucoma
(a disease characterized by ↑ intraocular pressure)
Optic disc drusen
(calcified nodules located within the optic disk – the most anterior part of the optic nerve)
Diabetes
Dyslipidemia
Hypertension
Vasculitis
(inflammation of blood vessels; e.g., sarcoid, Systemic Lupus Erythematosus)
Endothelial damage
Pupillary responses do not vary between both eyes when a light is shone in one eye at a time
Relative afferent pupillary defect (RAPD) mild or absent
Lost vascular wall integrity
Normal retinal electrical response to a light stimuli
Normal
electro- retinography (ERG) with b- wave >60%
Few scattered Intra-retinal hemorrhages
↓ In retinal electrical response to a light stimuli
Pupils respond differently to a light stimulus shone in one eye at a time
Severe ↓ in visual acuity (Snellen acuity of <20/400) Visual field deficits ↓ b-wave amplitude (<60%) on ERG RAPD present ↑ Pressure compromises retinal vein outflow Central retinal atherosclerosis (build-up of fat & cholesterol plaque in arteries) & hardening Atherosclerotic changes in the central retinal artery compress the central retinal vein (since they are both held together in region of the optic disc) Venous stasis (stagnation of blood flow) ↑ Likelihood of thrombus formation Central Retinal Vein Occlusion (CRVO) A common retinal vascular disease characterized by blockage of the main vein that drains blood from the retina CRVO classified based on the degree of perfusion (as seen through retinal angiography) Ischemic (nonperfused) CRVO ↑ Intraluminal venous pressure Dilated tortuous retinal veins Normal visual fields Vascular wall integrity lost Four-quadrant hemorrhages described as “blood and thunder” on fundus exam Obstruction due to thrombus ↓ Retinal capillary perfusion causes ischemia Hypoxia in the retinal tissues ↑ Release of vascular endothelial growth factor to revascularize diseased tissue & overcome hypoxic conditions Angiogenesis (formation of new blood vessels) Intraretinal infarcts “Cotton wool spots” on fundus exam Venous capillary fluid/protein leakage Mild retina, macula and disc edema Moderate ↓in visual acuity often (Snellen acuity >20/400)
New vessel proliferation can occur in the anterior chamber of the eye
This change can block the outflow path of the aqueous humor in the eye
Neovascular glaucoma
Neovascular vessels are structurally different in comparison to regular retinal vasculature
Neovascular vessels are more fragile
↑ Likelihood of rupture Vitreous hemorrhage
Neovascular vessels lack tight junctions
↑ Fluid leakage
Retina, macula and disc edema
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
First Published June 28, 2017, updated March 4, 2023 on www.thecalgaryguide.com