Transient Vision Loss

https://www1.racgp.org.au/ajgp/2021/march/blackout-understanding-transient-vision-loss

Key concept

• Transient vision loss may reflect pathology in the:
  • Eye
  • Optic nerve
  • Orbit
  • Brain
  • Neck vessels
  • Heart
• Main first step is to determine whether it is:
  • Monocular — one eye
  • Binocular — both eyes or hemifield disturbance
• Patients often struggle to distinguish this, so ask:
  • “Did you cover one eye during the episode?”
  • “Was the visual world split, such as seeing half a face or half a TV?”
• “Seeing half of the world” usually implies a post-chiasmal/binocular process.

Important history

• One eye or both eyes affected
• Sudden or gradual onset
• Duration of symptoms
• Speed of recovery
• Complete or partial recovery
• Positive visual phenomena:
  • Zigzags
  • Scintillations
  • Flashing lights
  • Kaleidoscope effects
• Negative visual phenomena:
  • Curtain coming down
  • Blackout
  • Greyout
  • Loss of hemifield
• Associated symptoms:
  • Headache
  • Nausea/vomiting
  • Photophobia/phonophobia
  • Diplopia
  • Vertigo
  • Dysphagia
  • Limb weakness/numbness
  • Gait disturbance
  • Jaw claudication
  • Scalp tenderness
  • Ocular pain/redness
• Past history:
  • Migraine
  • TIA/stroke
  • AF
  • Carotid disease
  • Hypertension
  • Diabetes
  • Smoking
  • Neck trauma

Red flags for transient vision loss

Monocular transient vision loss
Associated clinical findings	Likely diagnosis	Referral
Jaw claudication and temporal scalp tenderness	Giant cell arteritis	Immediate (<24 hours) ophthalmology or emergency department assessment
Only present when looking in a certain direction of gaze	Tumour compressing the optic nerve	Urgent (<24 hours) imaging (computed tomography of the brain and orbits), followed, if appropriate, by urgent (<48 hours) neurosurgical review
Precipitated by postural changes	Papilloedema	Urgent (<24 hours) imaging (computed tomography of the brain and orbits) followed, if appropriate, by urgent (<24 hours) neuro-ophthalmology, neurology or neurosurgical review
Red, painful eye	Acute angle-closure glaucoma	Immediate (<1–2 hours) ophthalmology review
Signs or history of neck trauma +/– Horner’s syndrome	Dissection of internal carotid artery	Immediate emergency department assessment
Binocular transient vision loss
Associated clinical findings	Likely diagnosis	Referral
Blurred vision presenting prior to a headache, may be associated with nausea, vomiting, phonophobia, photophobia	Migraine	Non-urgent neurology review
Blurred vision presenting after headache onset	Occipital tumour or arteriovenous malformation	Urgent (<24 hours) imaging (computed tomography of the brain and/or angiogram) and, if appropriate, urgent (<24 hours) neurosurgical review
Precipitated by postural changes or Valsalva manoeuvre	Papilloedema	Urgent (<24 hours) imaging (computed tomography of the brain and orbits) followed, if appropriate, by urgent (<24 hours) neuro-ophthalmology, neurology or neurosurgical review
Additional neurological symptoms including vertigo, perioral numbness, gait disturbance, dysphagia and unilateral or bilateral weakness or paraesthesia	Vertebrobasilar insufficiency	Urgent (<24 hours) neurology review

Monocular transient vision loss

• Main causes:
  • Amaurosis fugax
  • Retinal vascular occlusion/incipient occlusion
  • Retinal vasospasm
  • Acute angle-closure glaucoma
  • Dry eye/tear film instability
  • Papilloedema
  • Optic nerve/orbital tumour
  • Pituitary tumour compressing optic nerve
  • Giant cell arteritis
  • Internal carotid artery dissection

Amaurosis fugax

• Retinal equivalent of a TIA
• Usually embolic
• Common embolic sources:
  • Carotid atherosclerotic plaque
  • Cardiac valvular disease
  • Aorta
  • Internal carotid artery dissection
• Typical description:
  • Sudden monocular vision loss
  • “Curtain coming down”
  • Usually resolves within 1 hour
  • Often resolves within <10 minutes
  • Other eye remains normal
• Requires urgent ophthalmology/neurology assessment.
• Important investigations:
  • ECG
  • Holter monitor
  • Carotid Doppler ultrasound
  • Consider echocardiography
  • Vascular risk assessment and secondary prevention.

Giant cell arteritis red flags

• Age >50 years
• Transient visual loss
• Jaw claudication
• Temporal scalp tenderness
• Fever of unknown origin
• Myalgia/polymyalgia symptoms
• Thickened/tender/non-pulsatile temporal artery
• Requires immediate ED/ophthalmology assessment and high-dose corticosteroids to prevent permanent visual loss.
• Investigations:
  • FBE
  • ESR
  • CRP
  • Temporal artery biopsy

Acute angle-closure glaucoma

• Red flag features:
  • Painful red eye
  • Haloes around lights
  • Nausea/vomiting may occur
  • May be triggered by pupil dilation/darkness
• Requires immediate ophthalmology review, usually within 1–2 hours.

Papilloedema

• Can cause monocular or binocular transient visual obscurations.
• Usually described as:
  • Greyout/brownout rather than blackout
  • Lasts seconds
  • Triggered by bending, coughing, straining or Valsalva
• Requires urgent neuroimaging and neuro-ophthalmology/neurology/neurosurgical review.

Optic nerve/orbital tumour red flags

• Vision loss occurs only in a certain direction of gaze.
• May suggest optic nerve compression.
• Requires urgent CT brain/orbits and possible neurosurgical review.

Internal carotid artery dissection

• Consider if:
  • Neck trauma
  • Head/neck pain
  • Horner’s syndrome
  • Transient monocular vision loss
• Requires immediate ED assessment and vascular imaging.

Binocular transient vision loss

• Main causes:
  • Migraine aura
  • Orthostatic hypotension/presyncope
  • Vertebrobasilar insufficiency
  • Papilloedema
  • Occipital tumour
  • Arteriovenous malformation
  • Global cerebral hypoperfusion from arrhythmia/structural cardiac disease

Migraine aura

• Most common cause of transient binocular visual disturbance.
• Typical features:
  • Positive visual phenomena
  • Scintillations
  • Zigzags
  • Shimmering lights
  • Kaleidoscope/geometric patterns
  • Gradual expansion over 20–30 minutes
  • Visual symptoms usually precede headache
  • May occur without headache — acephalgic migraine
• Often followed by:
  • Nausea
  • Photophobia
  • Phonophobia
  • Malaise
• Normal ocular and neurological examination expected.
• Red flag:
  • Headache before visual symptoms may suggest occipital tumour or AVM and needs urgent imaging.

Vertebrobasilar insufficiency

• Usually in older patients, especially >50–60 years.
• Risk factors:
  • Hypertension
  • Diabetes
  • Ischaemic heart disease
  • Smoking
  • Atherosclerosis
• Symptoms:
  • Sudden bilateral visual loss
  • Global vision loss or homonymous hemianopia
  • Usually resolves within minutes to <1 hour
• Associated neurological symptoms:
  • Vertigo
  • Perioral numbness
  • Dysphagia
  • Gait disturbance
  • Limb weakness
  • Paraesthesia
  • Difficulty walking or talking
• Requires urgent neurology review.

Orthostatic hypotension / presyncope

• Visual loss is usually binocular.
• Often described as progressive blackening over seconds to minutes.
• Triggered by standing from lying/sitting.
• Causes include:
  • Orthostatic hypotension
  • Vasovagal episodes
  • Arrhythmia
  • Structural cardiac disease
  • Global cerebral hypoperfusion
• Assessment:
  • Lying/standing BP
  • ECG
  • Consider Holter monitor

Examination checklist

• General observation:
  • Proptosis
  • Red eye
  • Ocular oedema
• Vital signs:
  • BP
  • Postural BP if relevant
• If age >50:
  • Palpate temporal arteries
• Eye examination:
  • Best corrected visual acuity
  • Pupil size
  • Direct and consensual light reflexes
  • Swinging torch test for RAPD
  • Extraocular movements
  • Visual fields to confrontation
  • Colour vision
  • Fundoscopy if able
• Neurological examination:
  • Cranial nerves
  • Limb power/sensation/reflexes
  • Cerebellar signs
  • Gait
• Vascular/cardiac:
  • Auscultate carotids for bruit
  • Auscultate orbit if concern for fistula/aneurysm
  • ECG if vascular/cardiac cause possible

Referral if

Finding	Possible diagnosis	Referral
Jaw claudication, scalp tenderness	Giant cell arteritis	Immediate ED/ophthalmology
Red painful eye	Acute angle-closure glaucoma	Immediate ophthalmology
Neck trauma ± Horner’s syndrome	Carotid dissection	Immediate ED
Vision loss with specific gaze direction	Orbital/optic nerve tumour	Urgent imaging
Postural/Valsalva-triggered greyouts	Papilloedema	Urgent imaging/neuro review
Binocular visual loss + brainstem symptoms	Vertebrobasilar insufficiency	Urgent neurology
Headache before visual symptoms	Occipital lesion/AVM	Urgent imaging

Practical approach

• Clarify monocular vs binocular.
• Identify red flags.
• Perform ocular, neurological, BP and cardiovascular assessment.
• Treat suspected amaurosis fugax as TIA-equivalent.
• Do not reassure unless history is clearly benign and examination is normal.
• If uncertain, refer urgently because serious ocular, vascular or neurological disease may be present.