Retinal Vascular or Arterial Occlusion
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Retinal vascular occlusion refers to the blockage of blood flow within the retinal arterial or venous system, leading to sudden vision loss.
Aetiology
- Central retinal artery occlusion (CRAO): embolism or thrombus obstructing the central retinal artery.
- Branch retinal artery occlusion (BRAO): partial blockage of a branch of the retinal artery.
- Central retinal vein occlusion (CRVO): thrombotic obstruction of the central retinal vein.
- Branch retinal vein occlusion (BRVO): venous blockage affecting a portion of the retina.
Pathophysiology
- Arterial occlusion results in ischaemia and infarction of the inner retina.
- Venous occlusion leads to increased venous pressure, haemorrhages, and macular oedema.
- Oxygen deprivation can cause neovascularisation and secondary complications.
Risk Factors
- Atherosclerosis.
- Hypertension.
- Diabetes mellitus.
- Carotid artery disease.
- Cardiac arrhythmias (e.g., atrial fibrillation).
- Hypercoagulable states.
Signs and Symptoms
- Sudden, painless monocular vision loss: hallmark of arterial occlusion.
- Scotomas or partial visual field defects: common in branch occlusions.
- Retinal whitening: in CRAO due to infarction.
- Cherry-red spot: seen in CRAO at the macula.
- Retinal haemorrhages: in venous occlusions.
Investigations
- Fundoscopy: identifies characteristic findings based on occlusion type.
- Fluorescein angiography: confirms perfusion defects.
- OCT (optical coherence tomography): evaluates macular oedema.
- Carotid Doppler ultrasound: assesses for embolic sources.
Management
1. Emergency Management:
- Ocular massage: may dislodge emboli in CRAO.
- Reducing intraocular pressure: acetazolamide or anterior chamber paracentesis.
- Immediate referral: all suspected CRAO cases require urgent ophthalmology assessment.
2. Long-Term Management:
- Anti-VEGF therapy: for macular oedema in CRVO or BRVO.
- Laser photocoagulation: for neovascularisation prevention.
- Systemic risk factor management: blood pressure, lipids, and diabetes control.
3. Referral:
- Ophthalmology: urgent referral for all cases.
- Cardiology: if embolic source is suspected.
- Neurology: in cases with stroke risk.
- Vascular surgery: if carotid artery disease is identified.