E. Central retinal artery occlusion – Explanation

Sudden painless loss of vision

The most common causes of a sudden painless loss of vision are as follows:

• ischaemic optic neuropathy (e.g. temporal arteritis or atherosclerosis)
• occlusion of central retinal vein
• occlusion of central retinal artery
• vitreous haemorrhage
• retinal detachment

Ischaemic optic neuropathy

• may be due to arteritis (e.g. temporal arteritis) or atherosclerosis (e.g. hypertensive, diabetic olderpatient)
• due to occlusion of the short posterior ciliary arteries, causing damage to the optic nerve
• altitudinal field defects are seen

Central retinal vein occlusion

• incidence increases with age, more common than arterial occlusion
• causes: glaucoma, polycythaemia, hypertension
• severe retinal haemorrhages are usually seen on fundoscopy

Central retinal artery occlusion

• due to thromboembolism (from atherosclerosis) or arteritis (e.g. temporal arteritis)
• features include afferent pupillary defect, ‘cherry red’ spot on a pale retina

Vitreous haemorrhage

• causes: diabetes, bleeding disorders
• features may include sudden visual loss, dark spots

Retinal detachment

• features of vitreous detachment, which may precede retinal detachment, include flashes of light or
  floaters (see below)

Differentiating posterior vitreous detachment, retinal detachment and vitreous haemorrhage