Sudden loss of vision is very distressing for patients. It can also sometimes cause unusual behaviour and it is important not to mistake this as psychogenic in origin!
Most of the causes require urgent referral to ophthalmology for assessment and treatment. You should refer all patients who:
  • Have acuity that does not improve with pinhole
  • Have any optic disc abnormalities
  • Have any acute visual disturbance of unknown cause – it is unlikely you will be able to make an exact diagnosis in primary care or even in the emergency department – unless you are particularly experienced with and have access to a slit lamp.
Beware of dilating the pupil due to chance of glaucoma
The painful red eye is usually indicative of less serious pathology and is considered separately.

Causes

  1. Retinal detachment
  2. Temporal Arteritis
  3. Vitreous haemorrhage
  4. Retinal vein occlusion
  5. Retinal artery occlusion
  6. Wet age related macular degeneration
  7. Anterior ischemic optic neuropathy
  8. Optic neuritis
  9. Posterior Vitreous Detachment
  10. Cerebrovascular accident
  11. Migraine

Retinal detachment

  • Sudden painless loss of vision
  • Preceded by flashing lights (photopia), floaters, visual field defects
  • Classically – “a curtain falling down over my vision”
  • Macula involved = Central vision loss
  • Macula NOT involved = peripheral field loss and visual acuity maybe normal
  • Relative Afferent Pupillary Defect – (affected eye pupil dilates in response to light)
  • Sometimes cause by trauma
  • More common in:
    • Myopic individuals as they tend to have a thinner retina
    • Diabetic retinopathy
    • Previous surgery (eg. cataracts)

Ophthalmoscopy

  • Abnormal red reflex
  • If a large detachment you may be able to see the detached retina as a grey and wrinkled fold
  • Normal examination does not exclude diagnosis 
A severe case of retinal detachment

A severe case of retinal detachment

Management

  • If small or minor –  then laser to retinal tears – this burns the retina and this burns process encourages inflammation and subsequent healing around the affected area
  • If true retinal detachment (i.e. large pieces has detached) then – retinal surgery +/- vitrectomy

Temporal Arteritis

  • Sudden loss of vision (often with pain) – central scotoma
  • May be bilateral – often starts unilateral and then becomes bilateral
  • Due to occlusion of the ciliary arteries which supply the optic nerves
  • There may also be central retinal involvement
  • Usually patient over 65
  • Associated temporal headache and / or tenderness over the temporal arteries
  • Afferent pupillary defect
  • ESR elevated usually >40

Ophthalmoscopy

  • Swollen optic disc – later atrophies
  • Disc may appear normal

Management

  • Always remember to test the other eye too!
  • Steroids – give a stat dose of prednisolone 60-100mg, and continue for at least a week before tapering
  • Biopsy of temporal artery can confirm diagnosis

Also see full article on temporal arteritis

Vitreous haemorrhage

  • Sudden painless loss of vision (extent of loss depends on degree of haemorrhage)
    • large haemorrhage = TOTAL visual loss
    • small haemorrhage = presents as floaters and normal/slight reduced visual acuity
  • Sudden appearance of black spots/ cobwebs/ haze in vision
  • Can be diagnosed with ultrasound

Ophthalmoscopy

  • Decreased red reflex
  • RBC in anterior vitreous
  • May see blood clots in the vitreous that look like dark swirling clouds

Causes

  • Proliferative diabetic retinopathy
  • Retinal detachment
  • Trauma
  • Age related macular detachment
  • Results from haemorrhage of retinal vessels
    • Can sometimes be spontaneous without an underlying cause

Management

  • Refer to ophthalmologist and determine cause – main reason for referral is often to rule out other differentials such as retinal detachment
  • Mange complications – e.g. glaucoma due to RBC occluding trabecular meshwork
  • Often resolves spontaneously – and bed rest may help encourage resolution
  • Rarely a surgical vitrectomy is required to stop the bleeding

Central Retinal Vein Occlusion (CRVO)

  • Sudden painless loss of vision – particularly central vision
  • Unilateral
  • Vision not improved with pinhole
  • If severe = RAPD (relative afferent pupillary defect)
  • Typically occurs in elderly patients

Ophthalmoscopy

  • Hyperaemic retina with engorged veins
  • Swollen optic disc
  • Multiple haemorrhages
  • Cotton wool spots
  • ‘Stormy sunset’ appearance

Causes

  • Raised intraocular pressure (chronic glaucoma, hypertension)
  • Hyperviscosity syndromes (polycythemia)
  • Vessel wall disease (e.g. diabetes, sarcoidosis, hyperlipidaemia)

Management

  • No treatment is effective
  • Treat the cause
  • Fibrinolysin may benefit some patients
  • Occasionally laser therapy is needed later – to treat neovascularisation
  • CRVO associated with arteriosclerosis – check BP

Amaurosis Fugax

This is basically a TIA (transient ischaemic attack) of the retina.

  • Transient loss of vision (may be completed or partial) due to a temporary occlusion of a retinal artery.
  • Typically lasts less than 60 minutes, and is usually due to an embolus from the carotid artery.
  • There may be associated signs of cerebral ischaemia – TIA-like symptoms – such as hemiparesis or slurred speech.
  • Risk of stroke in a patient who has had amaurosis fugal is about 2% per year.
  • These patients need thorough work-up – like any other TIA patient.

Central retinal artery occlusion

If amaurosis fugal is a TIA of the retina, then central retinal artery occlusion is a stroke of the retina.

  • Sudden painless loss of vision –  Unilateral
  • RAPD
  • Visual acuity markedly reduced – often no perception of light
  • Visual acuity not improved with pinhole
  • Can also classically present with “a curtain falling across the vision”
  • Need to rule out temporal arteritis as a cause (especially if painful) – do an ESR

Ophthalmoscopy

  • Often normal, especially initially
  • Retinal emboli may be visible
  • Pale retina with cherry red spot (macula is spared as receives branches from posterior ciliary artery

Causes

  • Arterial embolus from diseased carotid, valvular heart disease, AF
  • Temporal Arteritis – high  ESR!
  • Vasculitis (polyarteritis nodosa)
  • Artherosclerotic process (diabetes, HT)

Management

  • Check – BP, Pulse – AF?, Carotids – bruits? , Heart – murmur?
  • If patient seen early (<30 minutes since onset of symptoms) – massage of the globe with fingers through closed eyelids may help to dislodge the embolus
  • Rebreathe CO2 (paper bag)
  • IV acetazolamide 500mg – helps to rapidly reduce globe pressure which has been shown to improve outcome
  • Bloods for ESR – if temporal arteritis needs urgent steroids
  • Refer urgently!
  • Prognosis is extremely poor. Recovery is unlikely if not treated within 30 minutes. Cases of Amaurosis fugal will self resolve

Wet Age-related macular degeneration

  • Occurs in the elderly
  • Sudden distortion – straight lines seem curved and central blank patch of vision or, sudden blurring of vision
    • This can be assessed with a grid pattern on a chart
  • Decrease visual acuity with CENTRAL SCOTOMA
  • Caused by choroidal neovascular membranes that develop under the macular. These can then spontaneously bleed or leak fluid – hence the name ‘wet’
  • Peripheral vision remains normal
  • As opposed to ‘dry’ macular degeneration which is
    • Chronic slow process
    • Accounts for 90% of cases of macular degeneration
    • May be familial
    • Common in old age – “Age related macular degeneration”

Ophthalmoscopy

  • Drusen – yellow fatty deposits lipid under the retina
  • Subretinal haemorrhages
  • Hard exudates – appear white
  • Macular oedema
  • All of these features appear at the macula

Management

  • Treatments not very effective
  • Injection of antivascular endothelial growth factor medication into the vitreous (e.g. ranibizumab or bevacizumab)
  • Age related MD
    • Smoking Cessation
    • Vitamin combinations may slow down progression (Vitamins A,C,E, zinc, beta-carotene)

Optic Neuritis (Acute Optic Neuropathy / Retrobulbar neuritis)

  • Rapid progressive loss of vision – typically occurs over several days
    • Unilateral or bilateral
  • Maybe decreased colour vision
  • Decreased visual acuity
  • RAPD
  • Symptoms of underlying disease (MS, nerve ischemia, artherosclerosis, syphilis)
    • A proportion of patients later go on to develop multiple sclerosis
  • Typically female aged 20-40
  • Eye pain / discomfort on eye movement
  • Usually central visual loss (central scotoma)

Ophthalmoscopy

  • Normal or swollen optic disc
  • Optica atrophy and disc pallor may appear later

Management

  • Dont forget to also check the other eye
  • Steroids – proven to improve recovery time and reduce the risk of another event
  • MRI brain – to look for evidence of multiple sclerosis
  • Most patients recover spontaneously, but many are left with reduce acuity long term

Posterior Vitreous Detachment

  • With age, the body of the posterior vitreous shrinks and detaches from the retina
  • A normal physiological process that occurs in the majority of individuals by late middle age
  • Rarely it can also cause retinal detachment
  • Sudden onset of floaters, with flashing lights
    • Often asymptomatic
    • Flashing lights are suggestive of retinal traction
  • Visual acuity usually normal – if visual acuity is affected then consider associated retinal detachment
  • Visualisation of the retina often normal – usually not possible to tell there is vitreous detachment

Management

  • Refer urgently to ophthalmology to assess for retinal involvement – which we require urgent treatment (see above – retinal detachment)

Decision Tree

Have a go at this decision tree to differentiate the types of sudden visual loss

Adapted from table in Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt – Figure 77.5, Pg 884

References

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