4. Acute Loss of Vision Flashcards
How might the causes sudden loss of vision be categorised?
Categorised in Painless and Painful (sudden loss of vision)
What are the painless causes of sudden loss of vision studied?
- Vascular Occlusion
- Vitreous Haemorrhage
- Retinal Detachment
- Optic Neuritis
- Giant Cell Arteritis/Temporal Arteritis
What are the painful causes of sudden loss of vision studied?
- Acute Angle Closure Glaucoma
- Uveitis
- Keratitis
- Endophtalmitis
- Optic Neuritis
What information should be illicited during an loss of vision Hx?
Duration Nature of Visual Loss Painful or painless Any associated symptoms Systemic Medical Conditions
Describe the blood supply to the eye
Central Artery + Vein located in the optic nerve. Short & Long Posterior Ciliary Arteries Anterior Ciliary Arteries Vortex Veins Circulus Vasculosus Irids
(Courses of the CRV and CRA
2/3 from central retinal artery
1/3 (outor closer to the coroid) get blood from the coroid
Optic Nerve partly supplied from the short and long cilary arteries
Haemorrhage/Tortuous Vessels
Suggests central retinal vein occlusion causes congestion of the blood vessels
What are the risk factor for a retinal vein occlusion?
Hypertension Hyperlipidaemia Diabetes mellitus Smoking Raised IOP
(Elderly men, smokers, hypertensive Raised IOP e.g. glaucoma )
If not above, Hypercoagulable States (myeloproliferative disorders, antiphospholipid A, protein c/s deficiency etc)
Oral Contraceptive Pill
Who is most at risk of an occlusion of the central retinal vein?
(90% of CRVO occurs in patients > 55 years old)
70% of patients with CRVO aged over 50 have hypertension, and 25% of those younger than 50 have hypertension.
What is are the mechanisms of retinal vein occlusion?
Patient with hyperlipidaema + Vasculare sclerosis
Most common causes of occlusion of the vein is pressure from the adjacent artery.
Another arterial venous nipping (caused by artery crossing over)
What are the signs and symptoms of retinal vein occlusion?
Varies on the degree of ischaemia.
Usually unilateral
Worse the vision at presentation the worse the prognosis
Presents with acute painless onset of blurred vision
May have RAPD – depending on degree of retinal ischaemia
Visual Acuity often < 6/60
RAPD plus worse VA at presentation suggests ischaemic CRVO, and worse visual prognosis
Dilated Toruous veins
Extensive retinal flame haemorrhages (typical appearance depends on location in the retinal layer so if diabetic retinopathy they are deep in RVO they are superficial)
Swollen optic disc, caused by ischemic damage on nerve axons
Macular Oedema
Distinguish between ischemic and non-ischemic CRVO?
In both ischemic and nonischemic CRVO, blockage of the retinal vein occurs, but the nonischemic type is able to maintain better relative blood flow to the retina through collaterals.
The nonischemic type of CRVO is the milder clinical presentation and accounts for 75%-80% of cases. Neovascularization is rare. Unfortunately, conversion to the ischemic type is common.
The ischemic type is associated with marked decreased vision, as ischemic CRVO predisposes to anterior neovascularization called rubeosis irides, which leads to high-pressure neovascular glaucoma.
Neovascularization in the posterior eye can lead to vitreous hemorrhage and retinal detachment.
Describe the management of CRVO?
Establish the aetiology…
Elderly patient – BP, Chol, ESR (exclude GCA)
<40 years old – investigate for hypercoaguable state
Risk factor management = consider starting aspirin
Visual prognosis depends on degree of retinal ischaemia
Non-ischaemic CRVO – better prognosis Ischaemic CRVO (15%) – poor prognosis, risk of rubeosis iridis
What are the potential complication of Retinal Ischemia?
Macular oedema – treat with IVT anti-VEGF injections
Neovascularisation – pan-retinal photocoagulation, IVT anti-VEGF, treat IOP if rubeotic glaucoma.
Describe the different aetiologies of Central Retinal Artery Occlusion?
Embolic (Carotid disease, cardiac/valvular, Afib) – Vast majority
Thrombus (Atherosclerosis, coagulopathies)
Other (Inflam/vaculitis, vasospasm, traumatic vessel damage)
How does retinal artery occlusion usually present?
Presents with acute painless severe loss of vision (hands, response to light only, ischaemia makes vision loss >likely)
Most patients > 60 years old; men > women
Usually Unilateral (Only 1-2% bilateral)
Thinned attenuated, pale appearance of blood vessels
Blurry vessels a sign of oedema
Bright red spot macula (cherry spot)
What are the characteristic of branch retinal artery occlusions?
Branch retinal artery occlusion (BRAO) occurs when the embolus lodges in a more distal branch of the retinal artery. BRAO typically involves the temporal retinal vessels and usually does not require ocular therapeutics unless perifoveolar vessels are threatened. The central retinal artery is affected in 57% of occlusions, the branch retinal artery is involved in 38% of occlusions, and cilioretinal artery obstructions occur in 5% of occlusions.[1]
