Sudden loss of vision

Question 1

Occlusion of the central retinal vein

Answer 1

One of the most common causes of sudden painless unilateral loss of vision

CRVO is a condition where the vein draining blood from retina closes off partially or fully

Causes: thrombus formation and predisposing factors - HTN, DM, smoking and obesity. Raised intraocular pressure, sarcoidosis, hyperviscosity e.g. myeloma, thrombophilic disorders

Presentation: unilateral, painless blurred vision , visual field defect

Fundoscopy:

• Non-ischaemic: mild or absent pupillary defect, widespread dot and flame haemorrhages throughout fundus
• Ischaemic: severe visual impairment with marked afferent pupillary defect, dot and flame haemorrhages throughout fundus, cotton wool spots ± retinal detachment

Management

• Refer within 24hrs to opthalmology
• Laser treatment , VEGF inhibitors e.g. ranibizumab

Question 2

Occlusion of the central retinal artery

Answer 2

Due to thromboembolism (atherosclerosis) or Arteritis (GCA)

Clinical features: preceeded by acute onset of flashers and floaters. Results in reduced visual acuity. Painless

Fundoscopy: pale retina, cherry red spot area

Management: urgent referral

Question 3

Vitreous haemorrhage

Answer 3

Bleeding into vitreous humour

One of the most common causes of painless visual loss

Varies from haziness and floaters to complete loss of vision

Cause: diabetic retinopathy, ocular trauma, shaken baby, high myopia (increases risk of retinal tears, detachment and associated vitreous haemorrhage

Question 4

Retinal detachment

Answer 4

Most are preceeded by a posterior vetreous detatchment which causes traction on the retina and potentially a retinal tear

Initial detachment may be localized or broad, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is almost always classified as a medical emergency. Permanent damage may occur if the detachment is not repaired within 24–72 hours

Question 5

Optic neuritis

Answer 5

Occurs when inflammation damages the optic nerve

Triad of clinical features: reduced vision, eye pain on movement, impaired colour vision

Question 6

Ischaemic optic neuropathy

Answer 6

Loss of vision caused by damage to the optic nerve as a result of ischaemia

Two types: arteritic and non arteritic

Typical presentation: sudden loss of vision in one eye upon wakening, vision obscured by dark shadow, no pain