Ophthalmology - Sudden Loss of Vision (Optic neuritis, Arterial and Venous Occlusion, Ischaemic Optic Neuropathy, Vitreous Haemorrhage and Detachment, Retinal Detachment)

Question 1

Name some causes of sudden loss of vision

Answer 1

• Optic neuritis
• Vitreous haemorrhage
• Central retinal artery occlusion
• Retinal vein occlusion (central or branch)
• Retinal detachment
• Anterior ischaemic optic neuropathy

Question 2

What is optic neuritis? Name some causes

Answer 2

-Inflammation of the optic nerve (often demyelinating)

Causes:

• MS
• DM
• Syphillis

Question 3

Name some symptoms of optic neuritis and outline management and important imaging

Answer 3

Symptoms

• Pain on eye movements
• Decreased visual acuity
• Decreased colour vision
• Afferent defect

Management

• MRI: enhancement of the optic nerve
• High dose steroids (in treatment for MS)- IV if severe flare or previously failed PO steroids.

Question 4

What is central retinal artery occlusion? Give some causes

Answer 4

-Blockage of blood through central retinal artery (branch of ophthalmic artery), which supplies blood to the retina.

Causes

• Atherosclerosis (most common)
• Giant cell arteritis
• Thromboembolism: clot, infective, etc

Question 5

Name some risk factors for central retinal artery occlusion

Answer 5

CVS risk factors

• Obesity, smoking, sedentism, poor diet, alcohol
• HTN, hyperlipidaemia
• Older age
• DM

Rheumatological risk factors

• Polymylagia rheumatica
• GCA
• >50 years of age

Question 6

What is the presentation of someone suffering from central retinal artery occlusion? What are some important findings on Fundoscopy?

Answer 6

• Dramatic unilateral painless visual loss (occurs in seconds)
• Afferent pupil defect: loss of light sensation by Ischaemic retinal
• Fundoscopy: pale retina (due to retinal ischaemia) and cherry red spot (macula is thinner than rest of retina, redness is caused by the underlying choroid layer)

Question 7

What is the treatment for central retinal artery occlusion?

Answer 7

Therapy aimed at dislodging thrombus (none of these have a very strong evidence base)

• Occular massage
• Surgical removal of aqueous fluid
• Inhaling carbogen (5% CO2, 95% O2) to dilate artery
• Isosorbide dinitrate to dilate the artery

Question 8

What is vitreous haemorrhage? Name some causes

Answer 8

-Haemorrhage within the vitreous humour

Causes:

• Neovascularisation (DM)
• Retinal tears/detachment
• Trauma

Question 9

Describe the PC of someone presenting with vitreous haemorrhage and describe the management

Answer 9

Presentation is variable based on degree of bleeds:

• Large bleeds: sudden vision loss, loss of red reflex and inability to visual the retina
• Moderate bleeds: numerous dark spots
• Small bleeds: floaters in vision or small dark spots

Management:

• Some VH undergo spontaneous absorption
• Vitrectomy may be performed in dense VH

Question 10

What is retinal vein occlusion?

Answer 10

-Central retinal vein occlusion: thrombus forms in retinal veins and blocks the drainage from the retinal, leading to pooling of blood in retina, macular oedema and retinal haemorrhages
-The central retinal vein runs through the optic nerve and is responsible for draining blood from the retina.
-Central retinal vein is made of 4 branches: blockage in a branch causes more localised signs.
*release of VEGF to stimulate neovascularisation is damaging

Question 11

What is the PC of central retinal vein occlusion? Name some findings on Fundoscopy and other investigations you should perform

Answer 11

-Sudden, unilateral painless loss of vision

Fundoscopy

• Flame and blot haemorrhages
• Optic disc and macular oedema
• Tortuous dilated vessels
• Cotton wool spots

Other investigations

• FBC: leukaemia
• ESR: inflammatory disorers
• BP: HTN
• Serum glucose/HbA1c: DM

Question 12

How do you manage retinal vein occlusion?

Answer 12

• Immediate referral to ophthalmology for assessment and management
• Aim to treat the macular oedema and prevent neovascularisation (isi and retina) and glaucoma

Options:

• Laser photocoagulation
• Intravitreal steroids or anti-VEGF therapies

Question 13

What is retinal detachment?

Answer 13

• Retinal separates from choroid underneath
• Usual due to a retinal tear: allows vitreous fluid to get under retinal and fill the space between retina and choroid.
• Outer retina relies on BVs from choroid for blood supply - therefore it is a sight threatening emergency.
• Can have tears or detachment

Question 14

Name some risk factors for retinal detachment

Answer 14

• Posterior vitreous detachment (discussed later)
• Diabetic retinopathy
• Trauma to the eye
• Retinal malignancy
• Older age
• FHx

Question 15

How will a patient with retinal detachment present?

Answer 15

• Painless vision loss: suddent and like a shadow coming across the vision (starts peripehrally and progresses towards the central vision)
• ‘Veil/curtain’ over field of vision
• Flashes and floaters
• Blurred/distorted vision (straight lines are curvy)

Question 16

How will you manage a patient who presents with retinal detachment? Name some important investigations

Answer 16

-Any patient who presents with painless floaters/flashes needs a detailed assessment of their retina ASAP

Investigations

• Visual acuity + visual fields
• Slip lamp fundoscopy for detailed retinal assessment

Management

• Tears: aim is to create adhesions between retina and choroid to present detachment. Can used laser therapy or cryotherapy
• Detachment: aim is to reattach the retina and reduce any traction that may cause it to recur.
• Vitrectomy: remove relevant parts of vitreous body and replace with gas
• Scleral buckling: use silicon to put pressure on outside of eye to bring choroid in contact with detached retina
• Pneumtic retinopexy: injecting gas bubble into vitreous body and changing patient position to create pressure that flattens retina back into place

Question 17

What is this?

Answer 17

Retinal detachment

Question 18

What is posterior vitreous detachment? Why is this important in the context of retinal tears/detachment?

Answer 18

• Vitreous body is the gel (made of collagen and water) that maintains the structure of the eyeball and keeps the retina pressed in the choroid
• Vitreous body becomes less firm and less able to maintain the shape with age
• Posterior vitreous detachment occurs when the gel comes away from the retina, and no longer supports it/presses it down
• Big risk factor for retinal tears/detachment

Question 19

What is the presentation of posterior vitreous detachment?

Answer 19

• Does not cause sudden vision loss but does cause blurry vision, cobwebs across vision, floaters and flashing lights (usually in peripheral vision)
• Painless

Question 20

Name an important investigation finding in posterior vitreous detachment and outline the management for this condition

Answer 20

-On fundoscopy: Weiss sign - caused by cirular peripapillary attachment have it has become detached from the optic nerve head. Looks like a ‘ring-shaped floater’/

Management

• Must exclude and assess the risk of retinal tear or detachment through through assessment of retina
• No treatment necessary: over time brain adjusts to sx

Question 21

What is ischaemic optic neuropathy?

Answer 21

• Localised ischaemic even at the junction of the optic nerve as it enters the back of the eyeball.
• This portion of the optic nerve has no elastic ‘give’ and a small vascular insult can lead to swelling and vision loss
• The hemispheric vascular supply of the optic nerve usually causes an altudinal visual defect.