Retinal Venous Occlusion (RVO)

Retinal Venous Occlusion (RVO)

• Central retinal vein drains retinal circulation into the cavernous sinus via the superior ophthalmic vein.
• RVO is the second most common retinal vascular disorder after diabetic retinopathy, often leading to vision loss.
• RVOs show a strong correlation with systemic disease and are associated with high morbidity and mortality.

Risk Factors

• Patient age and systemic vascular diseases are key factors.
• RVO involves decreased venous outflow within the retinal circulation, resulting in macular edema and intraretinal hemorrhages.
• Vision loss is typically from macular ischemia or edema, retinal hemorrhages, and neovascular glaucoma.
• RVOs may include retinal arterial macroaneurysm formation and cilioretinal artery occlusions.
• Main risk factor for both Central Retinal Vein Occlusion (CRVO) and Branch Retinal Vein Occlusion (BRVO) is older age, with 50% of cases occurring in those >65 years old.
• Risk factors for BRVO include local vascular factors like arterial-venous crossing changes (AR retinopathy) and high IOP.
• Systemic conditions such as hypertension, hyperlipidemia, diabetes, and coronary artery disease increase risk for BRVO.
• Sudden onset unilateral painless vision loss indicates RVO, with the degree of loss depending on retinal ischemia.

Ischemic vs Non-Ischemic

• Severe vision impairment (<20/200) is associated with non-perfusion (ischemic RVO).
• Ischemic RVO involves vascular stasis, limiting blood circulation.
• Non-ischemic RVO permits vascular perfusion and has better visual acuity.

Testing and Evaluation

• Fluorescein Angiography (FA) evaluates the degree of ischemia.
• Optical Coherence Tomography (OCT) detects macular edema.
• Optical Coherence Tomography Angiography (OCTA) evaluates changes in microvasculature.
• VF testing monitors visual field defects.
• Assessments include medical history, ocular exam, and retinal imaging.
• Focus on vascular and blood disorders such as hypercoagulability.

Lab Work Considerations

• Complete CBC, glucose tolerance test and lipid profile
• Serum protein electrophoresis, a chemistry profile and hematologic tests.
• Syphilis serology and thrombophilic screening.
• Check for activated protein C resistance, lupus anticoagulant, anticardiolipin antibodies, protein C, protein S, and antithrombin III.
• Also check for vasculitis, inflammation, dehydration, and medication use.
• Assess glaucoma and ocular hypertension history.

Treatment and Prevention

• Essential first step is FA to detect nonperfused capillary areas and macular ischemia extent.
• OCT quantifies extend of macular edema
• OCTA assesses microvasculature changes to evaluate macular ischemia in RVO
• Systemic disease should be treated to prevent other eye involvement.

Differentials

• Consider Ocular Ischemic Syndrome and retinopathy of carotid occlusive disease.
• Ocular Ischemic Syndrome involves hemorrhages in the mid-periphery and dilated veins.
• Only CRVO has tortuosity.

Imaging

• MRA can show complete occlusion of the internal carotid arteries bilaterally.
• DR does not respect horizontal.
• Papilledema (bilateral) and papillophlebitis (unilateral) need to be ruled out
• CWS is main feature of radiation retinopathy
• History of radiation required

RVO Treatment

• Treat underlying medical disorders
• Discontinue oral contraceptives and change diuretics/antihypertensives if possible
• Reduce IOP if elevated
• Use anti-VEGF for macular edema and neovascularization
• PRP also an option for neovascularization

Anti-VEGF Studies & Treatments

• VIBRANT trial demonstrated efficacy of aflibercept over grid laser for macular edema in BRVO.
• The CRUISE study demonstrates ranibizumab improved vision and reduced macular edema
• GALILEO study indicates that bevacizumab found a 15-letter gain in treated eyes
• The SCORE2 found that aflibercept was similar to bevacizumab in mean visual acuity at 6 months
• Faricimab-svoa (Vabysmo) is FDA-approved for macular edema following RVO, a bispecific antibody approved for the eye for both, affecting VEGF-A and Ang-2.
• First-line treatment for macular edema due to CRVO is anti-VEGF therapy with intravitreal bevacizumab, ranibizumab, aflibercept or faricimab-svoa

Steroid Use

• Steroids are effective for macular edema associated with RVO but have risks of cataracts and glaucoma.
• The SCORE-BRVO study: triamcinolone showed similar efficacy to macular grid laser but had more IOP and cataract issues!
• Consider macular grid laser for BRVO eyes with perfused macular edema leading to vision loss
• GENEVA and COBALT studies found dexamethasone implants beneficial.
• Intravitreal triamcinolone and dexamethasone implant may be used in second line

Laser Photocoagulation

• Used if macular edema persists for 3-6 months in ME due ti BRVO
• Consider PRP for neovascularization
• CVOS Study 2 advises careful observation of ischemic CRVO

Follow-up

• Educate of 8-10% risk of development of a BRVO or CRVO in the fellow eye!
• VA 20/200 needs monthly F/U

Central Retinal Vein Occlusion (CRVO)

• CRVO involves occlusion of the central retinal vein the lamina cribosa
• Majority of CRVO patients are >50.
• Patients are systemic hypertension, diabetes, and open-angle glaucoma.
• Younger patients with CRVO may have an inflammatory etiology.

CRVO Etiology:

• Atherosclerosis of adjacent central retinal artery

CRVO Mechanical Compression

• CRA compresses the CRV in the lamina cribosa region, induces thrombosis.
• Retinal arteriole and vein share adventitial sheath.
• Elevated venous and capillary pressure with blood stagnation results in retinal hypoxia

CRVO Occlusion at the Lamina Cribosa

• Collagen tissue in adults aged 50 and older is stiffer, compressing the vessel.

Blood Disorders, Inflammation

• Can incite platelet aggregation
• Vascular stasis and exudation cause secretion of inflammatory factors.
• Acquired & Inherited hypercoagulable states can lead to CRVO

Non-Ischemic CRVO

• VA better than 20/400
• Pupils: NO RAPD or mild (like very small but no RAPD)
• Signs: dilated veins (all branches of CRV)

Ischemic CRVO

• VA: worse than 20/400, vision field constrictions
• Pupils: RAPD (larger)
• Signs: Retinal hemorrhages and dilated, tortuous retinal veins

Clinical findings of Ischemic CRVO

• Collaterals between retinal venules
• Neovascularization typically anterior > posterior
• Neovascular glaucoma affects 60% of those with Ischemic CRVO

Impending CRVO

• Mild symptoms, worse on awakening
• Signs of dilated veins
• Requires FA and OCTA

Hemiretinal Vein Occlusion (HRVO)

• Involves half of the neurosensory retinal venous drainage
• Clinical findings include vascular tortuosity and retinal hemorrhages

Branch Retinal Vein Occlusions (BRVO)

• Occur at arteriovenous crossing point
• Requires dilated and tortuous veins

BRVO Contributing Factors

• What are the two main risk factors for branch retinal retinopathy? high IOP and arteriosclerotic retinopathy
• Often secondary to compression

Retinal Arterial Occlusions (RAO)

• BRAO is less common than central occlusion.
• RAO can cause life-threatening conditions
• Needs to be treated ASAP, LIKE A STROKE

Causes

• Retina supplied by 2 branches of the ophthalmic artery
• Thrombus or emboli

RAO Treatment

• Acute, symptomatic OAO, CRAO, or BRAO need IMMEDIATE REFARRAL
• Give panretinal photocoagulation (PRP)
• Consider GCA

Ophthalmic Artery Occlusion (really bad, catastrophic)

• Requires RAPID assessment and diagnosis

Susac Syndrome

• Affects young women causing vision and hearing problems
• Needs prompt evaluation

Ocular Ischemic Syndrome

• Eye is ischemi to ocular area
• Causes monocular vision loss