Sudden Loss Of Vision Flashcards
What is visual loss? How do you classify?
This is the inability to perceive visual stimuli
Classification
Based on onset
1) Sudden
2) Gradual
Based on pain
1) Painful
2) Painless
What is sudden visual loss
This is the inability to perceive visual sensations that happens within minutes to hours and lasts for more than 24 hrs.
What is amaurosis fugax
This is the transient loss of vision in one or both eyes. It can occur from occlusion of an optic artery. It usually takes seconds to minutes for full recovery.
List the causes of sudden painless loss of vision
•Central retinal artery occlusion
•Massive vitreous haemorrhage
•Retinal detachment (involving macular area)
•Central retinal vein occlusion
•Anterior Ischaemic Optic Neuropathy
•Cerebrovascular accident (occipital lobe)
•Central serous retinopathy
•Optic neuritis
List the causes of painful loss of vision
• Acute congestive glaucoma
• Acute iridocyclitis
•Ocular trauma (mechanical, chemical etc)
What are the presenting symptoms and signs of acute congestive glaucoma?
Symptoms
• Pain
• Redness
• Decrease vision
• Diaphoresis
• Nausea
• Vomiting
Signs
• Hyperaemia (ciliary injection)
• Cornea oedema
• Dilated unreactive pupil
How would you manage acute congestive glaucoma
•Hyperosmotic agent: mannitol, glycerol, isosorbide
•Acetazolamide (CAI)
•Pilocarpine (Cholinergic agonist)
•Beta-blockers (eg atenolol)
•Steroids
•Peripheral iridotomy or YAG laser iridotomy (clear cornea required)
What is central venous vein occlusion. List the risk factors
This is the blockage of the central venous vein usually at the level of the LAMINA CRIBROSA.
RISK FACTORS
• Hypertension
• Old age
• Diabetes mellitus
• Oral contraceptive use
• Pressure on vein by sclerotic artery (common adventitia)
• Hyperviscosity situations like polycythemia, hyperlipidemia, macroglobulinemia
• Periphlebitis retinae
• Raised intraocular pressure
• Orbital cellulitis
• Cavernous sinus thrombosis
Classification of Central Retinal Venous Occlusion (CRVO)
It is classified into;
1) ISCHEMIC CRVO
In this type, there is severe occlusion causing stasis at capillary level. This will eventually affect the arteries and thus reduce perfusion of retinal tissues and eventually making them ischemic.
2) NON ISCHEMIC CRVO
In this case, there is partial occlusion of the central retinal vein which still allows perfusion of the retina.
What is the most common type of central rations vein occlusion
Non-ischemic (75%)
Ischemic (25%)
List the clinical findings of ischemic CRVO
1) Extensive retinal hemorrhage:- This is from back up blood in the veins. Gives a Blood and thunder appearance.
2) Cotton wool spots:- They are white patches seen due to infarction of the nerve fiber layers
3) Neovascularization:- This is due to decreased blood flow. Usually happens within 90 days and is a cause of secondary glaucoma. RUBEOSIS IRIDIS
4) Macular ischemia
5) VA < 6/60
6) Marked RAPD
7) Severe disc edema
8) Very poor prognosis
9) Marked venous tortuosity and engorgement
List the clinical findings of non-ischemic CRVO
• VA > CF
• RAPD: mild
• Mild venous tortuosity and dilatation
• Mild-moderate retinal haemorrhage
• Variable cotton-wool spots
• Mild to moderate disc oedema
• May convert to ischaemic
• Guarded prognosis
What are the treatment modalities for CRVO
•Intra vitreal anti vascular endothelial growth factor (anti-VEGF):- Prevents neovascularization and thus reduces macular edema
•Intra vitreal steroids eg triamcinolone:- Prevents inflammation
•Pan retinal photo-coagulation
•Underlying cause or risk factors should be treated
What are the classes of central retinal artery occlusion?
Arteritic
Non-arteritic
List the risk factors for central renal artery occlusion
- Atherosclerosis-related thrombosis at the level of lamina cribosa
- Emboli from the carotid artery / cardiac origin eg valvular disease, patent foramen ovale
- Systemic hypertension
- Diabetis mellitus
- Arteritis with obliteration: giant cell arteritis
- Angiospasm: amaurosis fugax
- Thrombophilic disorders / sickle cell disease / hypercoagulable states
