Ophthalmology - Sudden Loss of Vision (Optic neuritis, Arterial and Venous Occlusion, Ischaemic Optic Neuropathy, Vitreous Haemorrhage and Detachment, Retinal Detachment) Flashcards
Name some causes of sudden loss of vision
- Optic neuritis
- Vitreous haemorrhage
- Central retinal artery occlusion
- Retinal vein occlusion (central or branch)
- Retinal detachment
- Anterior ischaemic optic neuropathy
What is optic neuritis? Name some causes
-Inflammation of the optic nerve (often demyelinating)
Causes:
- MS
- DM
- Syphillis
Name some symptoms of optic neuritis and outline management and important imaging
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.
What is central retinal artery occlusion? Give some causes
-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
Name some risk factors for central retinal artery occlusion
CVS risk factors
- Obesity, smoking, sedentism, poor diet, alcohol
- HTN, hyperlipidaemia
- Older age
- DM
Rheumatological risk factors
- Polymylagia rheumatica
- GCA
- >50 years of age
What is the presentation of someone suffering from central retinal artery occlusion? What are some important findings on Fundoscopy?
- 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)
What is the treatment for central retinal artery occlusion?
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
What is vitreous haemorrhage? Name some causes
-Haemorrhage within the vitreous humour
Causes:
- Neovascularisation (DM)
- Retinal tears/detachment
- Trauma
Describe the PC of someone presenting with vitreous haemorrhage and describe the management
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
What is retinal vein occlusion?
-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
What is the PC of central retinal vein occlusion? Name some findings on Fundoscopy and other investigations you should perform
-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
How do you manage retinal vein occlusion?
- 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
What is retinal detachment?
- 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
Name some risk factors for retinal detachment
- Posterior vitreous detachment (discussed later)
- Diabetic retinopathy
- Trauma to the eye
- Retinal malignancy
- Older age
- FHx
How will a patient with retinal detachment present?
- 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)
How will you manage a patient who presents with retinal detachment? Name some important investigations
-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
What is this?
Retinal detachment
What is posterior vitreous detachment? Why is this important in the context of retinal tears/detachment?
- 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
What is the presentation of posterior vitreous detachment?
- Does not cause sudden vision loss but does cause blurry vision, cobwebs across vision, floaters and flashing lights (usually in peripheral vision)
- Painless
Name an important investigation finding in posterior vitreous detachment and outline the management for this condition
-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
What is ischaemic optic neuropathy?
- 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.
