Acute vision loss

Differential

Transient (Amaurosis fugax)

• TIA
• Papilloedema
• Migraine
• Functional

Painful persistent differential

• Acute angle closure glaucoma
• Optic neuritis
• Giant cell arteritis
• Uveitis
• Migraine
• Endophthalmitis
• Keratitis

Painless persistent differential

• Central retinal artery occlusion
• Central retinal vein occlusion
• Acute ischaemic optic neuropathy (AION)
• Optic neuritis
• Cataract
• Vitreous haemorrrhage
• Stroke
• Cortical blindness
• Retinal detachment
• Diabetic retinopathy
• Macular degeneration
• CMV retinitis
• Methanol
• Functional

Acute angle-closure glaucoma

• Lens or peripheral iris causes blockage of trabecular meshwork, obstructing outflow of aqueous humor
• Occurs more commonly if shallow anterior chamber, leading to failure of flow of aqueous from posterior to anterior chamber, pupillary block and forward bowing of iris, further narrowing the angle
• Acute attack usually precipitated by pupillary dilation, with precipitous increase in IOP

• Cornea pump mechanism is overwhelmed with subsequent corneal oedema, hazy appearance and foggy/haloes
• With ageing, lens becomes less elastic and thicker or cataracts can develop. These push the iris forward into greater contact with the lens, increasing pupillary block
• Hypermetropic (far-sighted) eyes have a shorter AP length, flatter cornea, narrower angle and are at increased risk

• Precipitants
  • Anything causing pupillary dilatation
  • Topical or systemic parasympatholytics e.g. mydriatics/antihistamines
  • Sympathomimetics e.g. adrenaline, pseudoephedrine
  • Dim illumination
  • Emotional upset

• Clinical features
  • Abrupt onset, painful, severe visual impairment if not rapidly treated
  • Severe eye pain/headache, blurred vision, nausea, vomiting
  • DDx: Migraine, temporal arteritis, SAH or intra-abdominal emergency
• Examination
  • Fixed, mid-position pupil and hazy cornea with conjunctival injection
  • IOP >20

• Treatment
  • Head up to 30 degrees
  • IV mannitol 1-2g/kg IV over 45 minutes (Rapidly drops IOP)
  • Topical timolol 0.5% 1 drop (Blocks production of aqueous humor)
  • Topical alpha-2 antagonist (apraclonidine 1%) 1 drop (Blocks production of aqueous humor)
  • Azetazolamide 500mg IV or PO (Blocks production of aqueous humor)
  • Topical pilocarpine 1-2% one drop q15min for 2 doses once IOP below 40, then four times daily
    • Pilocarpine will often not constrict the pupil until IOP is reduced due to pressure-induced ischaemic paralysis of iris
  • Topical steroids frequently recommended
  • Treat nausea/pain
  • Definitive treatment – Laser iridotomy

Optic neuritis

• May be mild to profound visual loss
• Usually unilateral and colour vision affected more than visual acuity
• Central scotoma is classic
• Red desaturation is key
  • As opposed to papillitis where colour saturation is preserved initially
• RAPD often present
• Fundoscopy shows swollen and oedematous optic disc in 30% (anterior optic neuritis)
• If optic nerve looks normal = retrobulbar optic neuritis

• Causes
  • Idiopathic
  • First presentation MS
  • Neuromyelitis optica
  • Anti-MOG syndrome
  • Post-childhood vaccination
  • Measles, mumps, chickenpox, encephalitis, herpez zoster, mononucleosis
  • Inflammation of meninges, sinuses, orbits
  • Syphilis, TB, cryptococcus and sarcoidosis

• DDx
  • Ischaemic optic neuropathy
  • Papilloedema
  • Hypertensive retinopathy
  • Orbital tumour compressing optic nerve (proptosis frequent
  • Methanol, heavy metals or chloroquine toxicity
• Need neurology and ophthalmology input

Central retinal artery occlusion

• Ophthalmic artery is the first branch off the internal carotid artery
• Central retinal artery is the first branch off the ophthalmic artery and supplies the central retina
• Ciliary arteries arise off ophthalmic atery after central retinal artery and supply the outer retina via choriocapillaries of choroid
• If central retinal artery occludes
  • Inner retina will infarct and become pale, less transparent and oedematous
  • Macula is thinnest part and intact underlying choroidal circulation becomes visible as cherry red spot

• Causes
  • Carotid or cardiac embolism
  • Retinal artery thrombosis
  • Giant cell arteritis
  • Vasculitis (lupus, PAN)
  • Sickle cell disease
  • Trauma
  • Vasospasm (mgraine)
  • Elevated IOP
  • Hypercoagulable states
  • Low retinal blood flow (carotid stenosis or hypotension)

• Sudden, profound, painless, monocular vision loss
• Often preceded by episodes of amaurosis fugax
• Very rare
• No evidence for treatment and only 1/3 regain functional vision
• Consult Ophthal and neurologist urgently and follow insitutional protocols
  • Digital massage, IOP-lowering drugs, paper bag, intra-arterial tPA within 20 hours
• Irreversible loss of vision the norm after 4 hours of ischaemia

Central retinal vein occlusion

• Risk factors
  • Diabetes, HTN, cerebrovascular disease, cardiovascular disease, dyslipidaemia, hypercoagulable states, vasculitis, glaucoma and compression of vein in thyroid disease or orbital tissues
• Loss of vision may be vague blurring to rapid, painless, monocular complete loss of vision
• Fundoscopy shows ‘blood and thunder’ with optic disc oedema and diffuse retinal haemorrhage
• No specific treatment is available

Retinal detachment

• Need to determine if flashers/floaters are monocular or binocular
  • Binocular complaints = intracranial (e.g. migraine)
  • Monocular = isolated to affected eye
• Usually >55yo (or younger if severely nearsighted) get tension from vitreous gel on retina causing stimulation and flashes
• If separation occurs, get floaters
• May present with flashes, floaters, veil or curtain and decreased peripheral and/or central visual acuity
• Need diagnosis within 24 hours by ophthal
• Most tears occur peripherally and are not visible on direct fundoscopy
• Diagnosis is made by history and confirmed by indirect fundoscopy
• Bedside USS can show detachment
  • Triangle-shaped retina with traction at the optic disc and not passing anterior to the ora serrata

Posterior vitreous detachment

Choroidal detachment

May progress anterior to the ora serrata and shows funnel-type appearance

Temporal arteritis

• Painless ischaemic optic neuropathy with profound visual loss and contralateral ocular involvement in days to weeks if not treated
• Usually >50 wth hx of PMR
• Symptoms include headache, jaw claudication, myalgias, fatigue, fever, anorexia and temporal artery tenderness
• May have associated TIA or stroke symptoms
• RAPID if optic nerve circulation involved
• Elevated ESR >50 usually present
• Added elevation of CRP also suggests diagnosis
• Treatment
  • IV methylpred 1g then then oral course of prednisolone
  • Biopsies remain positive for one week after initiation of steroid therapy

Papilloedema

DDx

• Intracranial mass
• Optic neuritis
• Idiopathic intracranial hypertension

Last Updated on September 5, 2024 by Andrew Crofton