D. Optic neuritis – Explanation

Whilst optic neuritis can present with sudden loss, in this 62-year-old man it is the least likely option.
Typically there is a unilateral decrease in visual acuity over hours or days. There may be poor
discrimination of colours and eye pain on movement
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 older
  patient)
• 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