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Medical Retina

Retinal Vascular Disease

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Retinal artery occlusion

Aetiology

  • Systemic

    • Carotid emboli: most common cause of BRAO

    • Cardiac emboli: most common in young patients

      • Atherosclerotic
      • Valvular
      • Infective (endocarditis)
      • Myxomatous (rare)

    • Vasculitic

      • Giant cell arteritis
      • SLE, PAN etc.

    • Coagulation disorders:

      • Anti-phospholipid
      • Protein C/S deficiencies

    • Pharmacological

      • Cocaine
      • Oral contraceptive

  • Ocular: raised IOP

    • Retrobulbar haemorrhage
    • Orbital compression: tumour, inflammation
    • RD surgery eg. scleral buckling

Clinical features

  • Acute loss of vision
  • RAPD
  • Cherry-red spot: unmasking of choroidal circulation at foveola
  • Macular sparing in 20% population due to cilioretinal artery presence
  • Arteriole attenuation
  • Optic disc pallor

“Cherry-red spot” causes

  • CRAO
  • Macular hole
  • Commotio retinae
  • Quinine toxicity
  • Tay-Sach’s
  • Gangliosidoses

Management

Acute management

  • No proven benefit
  • Ocular massage: eg. with three-mirror contact lens for 10s pressure followed by 5s release
  • Anterior chamber paracentesis
  • Intravenous diamox
  • Hyperbaric oxygen
  • Re-breathing expired air to increase carbon dioxide concentrations and thereby vasodilate

EAGLE study (NOT the same as early lens extraction for PACG study)

  • No benefit of tPA and increased systemic adverse effects

Early-long term management

  • Immediate referral to TIA/stroke clinic

    • Consideration of carotid doppler +/- echocardiography and secondary preventive measure

  • Management of complications

    • Neovascularisation of iris, angle, retina
      • anti-VEGF
      • PRP
      • Management of glaucoma including cyclodiode

Prognosis

  • 20% mortality within 5 years
  • 20% iris neovascularisation within 3 months
  • <5% neovascular glaucoma

Retinal vein occlusion

The most common cause of vein occlusion is compression by adjacent atherosclerotic retinal artery.

Natural history/prognosis

  • Vision in CRVO tends to deteriorate over time
  • 30% of non-ischaemic cases convert to ischaemic over 3 years
  • >90% of ischaemic CRVO patients have final VA <6/60
  • BRVO prognosis is better with 50-60% achieving at least 6/12 vision untreated at 1 year
    • Initial VA of better than 6/12 can reasonably be observed for spontaneous resolution

Epidemiology

  • Second commonest cause of reduced vision due to retinal vascular disease (after diabetic retinopathy)

  • BRVO is more common than CRVO

  • <10% are bilateral at presentation

  • Risk factors

    • Hypertension
    • Diabetes
    • Hyperlipidaemia
    • Hyperhomocysteinaemia
    • Coagulation disorders including haematological malignancies
    • Inflammatory disease/vasculitis: Behcet’s, PAN, sarcoidosis, GPA
    • Glaucoma
    • Short axial length/hyperopia
    • Retrobulbar compression: including in TED, orbital tumour or retrobulbar haemorrhage

  • Conflicting results on whether RVO predicts stroke or death

Clinical features

  • Dilated and tortuous veins
  • Haemorrhages
  • Vitreous haemorrhage
  • Cotton wool spots
  • Disc swelling
  • Macular oedema

Ischaemia

Features of ischaemic CRVO

  • Visual acuity <6/60
  • RAPD
  • Widespread deep intraretinal hemorrhages
  • >10 cotton wool spots
  • A degree of retinal vein dilatation and tortuosity
  • Electronegative ERG (reduced b-wave amplitude)
  • >10 disc diameters of capillary fall-out on FFA

Note

5 or more disc areas of capillary non-perfusion define an ischaemic BRVO

50% develop rubeosis and neovascular glaucoma (100 day glaucoma)

Tests

The main aim of investigations is to treat commonly associated risk factors (there is minimal evidence that the disease course or recurrence risk is affected)

  • Blood pressure
  • Serum glucose
  • FBC (to detect leukaemia)
  • ESR (to detect myeloma)
  • OCT
  • FFA if diagnosis uncertain: can identify ischaemic cases

Management

  • Management of systemic conditions

Macular oedema

  • Laser photocoagulation

    • CVOS: no difference in final VA for CRVO
    • BVOS: gain of 1.3 lines on average after three years in BRVO
      • Guideline recommends laser for macular oedema in BRVO if:
        • >3 months duration
        • VA 6/12 or worse
        • No significant macular haemorrhage
        • FFA shows capillary perfusion
      • Very few meet these criteria therefore in practice this treatment is reserved for those who cannot undergo or do not want IVT

  • Intravitreal steroids (triamcinolone)

    • SCORE study: showed short-lived anatomical and functional improvement in CRVO (an unpreserved form of triamcinolone was used)
    • GENEVA study: sustained-release dexamethasone (Ozurdex 0.7mg) achieved higher letter gain compared to sham (both BRVO and CRVO). 19% required IOP-lowering therapy and 0.7% needed IOP-lowering surgery

  • anti-VEGF

    • Intraocular VEGF levels are significantly higher in CRVO patients compared to normal controls

    • CRUISE study: lucentis (0.3mg and 0.5mg) for macular oedema in CRVO. 0.5mg treatment group achieved mean 14.9 letters compared to sham at 6 months

      • Follow-up HORIZON study: long-term PRN lucentis was well tolerated. Reduced frequency of injections associated with worse outcomes

    • BRAVO study (equivalent to CRUISE for BRVO): 0.3mg and 0.5mg lucentis for macular oedema in BRVO. Mean gain of 18.3 letters at 6 months in 0.5mg group and >97% reduction in foveal thickness.

    • GALILEO study: RCT comparing eylea to sham for macular oedema in CRVO. Treatment group achieved significantly higher mean change in BCVA at 24 weeks. Difference declined over time

    • VIBRANT study: compared eylea to macular laser for BRVO macular oedema. Eylea achieved better mean gains in BCVA at 6 months and central retinal thickness

  • The BRAVO, HORIZON and RETAIN studies showed that monthly first then at least 3-monthly monitoring is required to sustain visual benefit when using PRN treatment

Neovascularization

  • Sectoral laser photocoagulation for neovascularisation at disc/iris
  • Management of neovascular glaucoma

Cardiovascular disease

Hypertensive retinopathy staging

  1. Mild narrowing of arterioles (‘silver wiring’)
  2. Generalised narrowing and arteriovenous compression (‘AV nipping’)
  3. Retinal oedema, exudates, cotton wool spots and haemorrhages
  4. Diffuse oedema with optic disc swelling (‘malignant hypertension’)

Other features

  • Elschnig’s pearls: choroidal infarcts
  • Ischaemic optic neuropathy

Ocular ischaemic syndrome

Causes

  • Carotid atherosclerosis
  • Cardiac failure (generally reduced perfusion)
  • GCA/vasculitis

Presentation

  • Reduced vision

  • Ocular pain (ache)

  • Anterior segment ischaemia

    • Red eye
    • Corneal oedema
    • Iris rubeosis and neovascular glaucoma
    • AC flare
    • Cataract

  • Posterior segment ischaemia

    • Vascular tortuosity and dilation
    • Retinopathy: microaneurysms, haemorrhages, exudates
    • Neovascularisation
    • Vitreous haemorrhage
    • Elschnig’s spots
    • Disc swelling

Tests

  • OCT: pervasive retinal thinning
  • FFA: delayed choroidal filling
  • ERG: reduced a and b wave amplitudes
  • Bloods including ESR
  • Carotid doppler

Management

  • PRP if neovascularisation
  • Management of neovascular glaucoma
  • Topical steroids
  • Cycloplegia
  • Management of systemic risk factors

Associations

  • 50% have ischaemic heart disease
  • 5-year mortality is approximately 40%

Carotid endarterectomy

  • Symptomatic patients with amaurosis, hemispheric TIA or non-disabling strokes with 70-99% carotid artery stenosis

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