Sudden visual loss

Sudden visual loss is loss of vision developing over seconds to hours, in one or both eyes, lasting more than 24 hours. It is an emergency.

Clinical relevance. Delay beyond 4 to 6 hours reduces the chance of recovery in retinal artery occlusion. Untreated arteritic ischaemic optic neuropathy leads to second eye loss within days to weeks in about a third of patients. Binocular loss with a field defect points to a brain lesion and is a stroke until imaging says otherwise.

Anatomy. Monocular loss localises anterior to the chiasm (media, retina, optic nerve). Binocular homonymous loss localises behind the chiasm. Bitemporal loss localises to the chiasm.

Classification.

• Painless monocular: retinal artery occlusion, retinal vein occlusion, vitreous haemorrhage, retinal detachment, ischaemic optic neuropathy, macular haemorrhage (wet macular degeneration), optic neuritis (often with pain).
• Painful monocular: acute angle closure glaucoma, optic neuritis, keratitis and corneal ulcer, uveitis, endophthalmitis, orbital disease.
• Binocular: stroke (occipital, posterior circulation), pituitary apoplexy, posterior reversible encephalopathy syndrome, severe hypertension and pre-eclampsia, toxic optic neuropathy, cortical blindness, functional loss.

Key distinctions. A relative afferent pupillary defect indicates retinal or optic nerve disease. A normal pupil response with loss indicates cortical or functional loss. A cherry red spot with a pale retina indicates central retinal artery occlusion.

History.

• Exact time of onset (clock time), and eye or eyes affected.
• Whether the loss was a curtain, a central blur or a grey area.
• Preceding flashes or floaters, pain, headache, jaw claudication, scalp tenderness, fever, weight loss.
• Transient episodes before (amaurosis fugax) and neurological symptoms.
• Trauma, eye surgery or injections.
• Diabetes, hypertension, atrial fibrillation, carotid disease, sickle cell disease, clotting disorders, multiple sclerosis.
• Pregnancy and postpartum state.
• Drug and substance use (methanol, cocaine, phosphodiesterase inhibitors), and family history of glaucoma.

Drug history. Anticoagulants and antiplatelets (haemorrhage), phosphodiesterase inhibitors, amiodarone, ethambutol, linezolid, corticosteroids, bisphosphonates, immune checkpoint inhibitors, and combined oral contraceptives (venous occlusion).

Examination.

• Visual acuity in each eye with pinhole, colour vision, pupils (swinging flashlight test for relative afferent pupillary defect), confrontation visual fields, eye movements, and intraocular pressure when angle closure is possible.
• Red reflex, slit lamp, and dilated fundus examination. Look for:
  • Pale retina with a cherry red spot (artery occlusion).
  • Extensive haemorrhages (vein occlusion).
  • Pale swollen disc with haemorrhages (ischaemic optic neuropathy).
  • Swollen disc (papillitis, papilloedema).
  • Retinal elevation or tear, and vitreous haemorrhage.
• Blood pressure in both arms, pulse rhythm, carotid bruit, heart sounds, temporal artery tenderness, thickening and absent pulse, and a full neurological examination.

Red flags

• Onset within 6 hours (artery occlusion, stroke) or any onset within 24 hours with neurological signs
• Age over 50 with headache, jaw claudication, scalp tenderness, fever or weight loss
• Flashes, new floaters and a curtain (retinal detachment)
• Red painful eye with halos and nausea
• Visual loss with proptosis, fever, or painful eye movement
• Homonymous or bitemporal field loss, diplopia, or other neurological signs
• Severe hypertension, pregnancy or postpartum state
• Recent eye surgery, injection or trauma
• Sudden loss after a sudden severe headache (pituitary apoplexy)

Special groups. Children: trauma, optic neuritis, retinoblastoma. Pregnancy: pre-eclampsia, central serous retinopathy, pituitary apoplexy, venous sinus thrombosis. Older adults: giant cell arteritis, vascular occlusion and macular degeneration. Region specific: methanol poisoning from illicit alcohol, sickle cell disease and HIV related retinitis.

Vascular

• Central and branch retinal artery occlusion (embolic from carotid or cardiac sources, giant cell arteritis, vasculitis, hypercoagulable states)
• Central and branch retinal vein occlusion (hypertension, diabetes, glaucoma, hyperviscosity, oral contraceptives)
• Arteritic and non-arteritic anterior ischaemic optic neuropathy, posterior ischaemic optic neuropathy
• Ocular ischaemic syndrome, sickle cell retinopathy, vitreous haemorrhage from proliferative diabetic retinopathy
• Amaurosis fugax progressing to infarction

Retinal and vitreous

• Rhegmatogenous retinal detachment, tractional detachment, retinal tear
• Wet age related macular degeneration with haemorrhage, macular hole, choroidal neovascularisation
• Vitreous haemorrhage (diabetes, posterior vitreous detachment with tear, trauma, sickle cell disease, macroaneurysm, age related macular degeneration)
• Acute retinal necrosis, cytomegalovirus retinitis, endophthalmitis

Optic nerve

• Optic neuritis (multiple sclerosis, neuromyelitis optica spectrum disorder, MOG antibody disease, infection, sarcoidosis)
• Compressive optic neuropathy, traumatic optic neuropathy, toxic optic neuropathy (methanol, ethambutol, linezolid)
• Papilloedema with raised intracranial pressure, pituitary apoplexy

Anterior segment

• Acute angle closure glaucoma, hyphaema, corneal ulcer, severe keratitis, lens dislocation

Central

• Occipital and posterior circulation stroke, haemorrhage, posterior reversible encephalopathy syndrome, migraine aura, cortical blindness (hypoxic injury), eclampsia
• Seizure related visual loss

Functional

• Functional visual loss (inconsistent examination, normal investigations)

Reasoning. Classify by laterality and pain, test the pupils, and examine the fundus. Treat time critical conditions at once while arranging confirmation.

First line. Visual acuity, pupils, fields, fundoscopy, intraocular pressure, blood pressure, glucose, ECG, and temperature. Capillary glucose excludes hypoglycaemia as a cause of cortical visual loss.

Blood tests.

• Full blood count, ESR, C reactive protein and platelet count. In giant cell arteritis, ESR over 50 mm/h and platelets over 400 x 10^9/L support the diagnosis, but normal values do not exclude it.
• Glucose and HbA1c, lipids, urea, creatinine, electrolytes, clotting screen, and blood cultures when infection is suspected.
• By suspicion, add: thrombophilia screen; autoimmune screen (antinuclear antibody, ANCA, antiphospholipid antibodies); syphilis serology; HIV; interferon gamma release assay; angiotensin converting enzyme; haemoglobin electrophoresis; protein electrophoresis; and aquaporin-4 and MOG antibodies.
• Toxicology and methanol level in suspected poisoning.

Imaging and eye tests.

• Optical coherence tomography (macular oedema, retinal layers), fluorescein angiography (vascular occlusion), and B scan ultrasound when the view is poor (retinal detachment, vitreous haemorrhage, intraocular mass).
• CT head within minutes for suspected stroke or haemorrhage, then MRI brain with diffusion weighted imaging, and MR or CT angiography of head and neck. MRI brain and orbits with gadolinium for optic neuritis, compressive and chiasmal lesions.
• Carotid duplex ultrasound, echocardiography, and prolonged cardiac rhythm monitoring for embolic sources in artery occlusion.
• Temporal artery ultrasound or biopsy for giant cell arteritis (biopsy remains useful up to 2 weeks after steroids start).
• Lumbar puncture with opening pressure (over 25 cmH2O in adults is abnormal) for suspected idiopathic intracranial hypertension, or inflammatory disease, after imaging.
• Visual evoked potentials and electroretinogram for unexplained loss.

Limitations. Early optical coherence tomography can be normal in optic neuritis. MRI diffusion weighting may miss small brainstem infarcts early. Normal ESR does not exclude giant cell arteritis.

Same day ophthalmology for every patient with sudden loss. Do not delay treatment for imaging when giant cell arteritis or artery occlusion is likely.

Central retinal artery occlusion (within 24 hours of onset). Treat as an acute stroke equivalent.

• Call the emergency stroke team. Position the patient supine.
• Firm ocular massage for 5 to 15 seconds then release, repeated. Anterior chamber paracentesis by ophthalmology when available.
• Thrombolysis with alteplase 0.9 mg/kg IV (maximum 90 mg, 10 percent as a bolus over 1 minute and the remainder over 60 minutes) or tenecteplase 0.25 mg/kg IV as a single bolus (maximum 25 mg). Give within 4.5 hours of onset when haemorrhage is excluded and other criteria are met. Evidence of benefit is limited and the stroke team decides.
• Aspirin 300 mg orally daily when thrombolysis is not given.
• Investigate and treat the embolic source: carotid endarterectomy for symptomatic stenosis of 50 to 99 percent (within 2 weeks); anticoagulation for atrial fibrillation (apixaban 5 mg twice daily; 2.5 mg twice daily if two of age 80 or more, weight 60 kg or less, creatinine 133 micromol/L or more); atorvastatin 80 mg orally at night; and blood pressure and diabetes control.

Giant cell arteritis. Start prednisolone 40 to 60 mg orally each morning before biopsy (do not wait for results), with aspirin 75 mg daily, a proton pump inhibitor and bone protection.

If visual loss is present, give methylprednisolone 500 mg to 1 g IV daily for 3 days, then oral prednisolone 1 mg/kg daily (maximum 60 to 80 mg). Arrange same day specialist review. Specialists may add tocilizumab as steroid sparing therapy. Taper over 12 to 24 months by response.

Retinal detachment and tear. Immediate ophthalmology: laser retinopexy, cryotherapy, pneumatic retinopexy, scleral buckle or vitrectomy. Keep the head positioned as advised, avoid heavy exertion, and keep nil by mouth when surgery is planned.

Vitreous haemorrhage. Ophthalmology, upright head position, exclusion of tear, laser or vitrectomy, and control of diabetes and anticoagulants.

Retinal vein occlusion. Ophthalmology for intravitreal anti-vascular endothelial growth factor injections (ranibizumab, aflibercept or bevacizumab, monthly then by response) or corticosteroid implants for macular oedema. Laser for neovascularisation. Systemic risk factor control (blood pressure, glucose, lipids, hyperviscosity, thrombophilia).

Acute angle closure.

• Acetazolamide 500 mg IV or orally then 250 mg orally every 6 hours (avoid in sulphonamide allergy and severe renal impairment).
• Timolol 0.5 percent 1 drop (avoid in asthma, heart block, bradycardia).
• Apraclonidine 1 percent 1 drop.
• Pilocarpine 2 percent 1 drop once pressure is falling.
• Antiemetic (ondansetron 4 mg IV; maximum 16 mg in a single dose).
• Laser peripheral iridotomy by ophthalmology.

Optic neuritis. Methylprednisolone 1 g IV daily for 3 to 5 days under neurology and ophthalmology care (hastens recovery; final visual outcome is unchanged), MRI brain, and plasma exchange for severe loss not responding. Low dose oral prednisolone alone is not used.

Non-arteritic anterior ischaemic optic neuropathy. No treatment of proven benefit. Control vascular risk factors and stop phosphodiesterase inhibitors. Aspirin 75 mg daily is commonly used (evidence is limited).

Wet macular degeneration. Urgent intravitreal anti-vascular endothelial growth factor therapy.

Stroke and cortical visual loss. Emergency stroke care:

• Alteplase or tenecteplase within 4.5 hours when haemorrhage is excluded.
• Blood pressure under 185/110 mmHg before and under 180/105 mmHg for 24 hours after thrombolysis.
• Aspirin 300 mg orally daily when thrombolysis is not given.
• Thrombectomy referral for large vessel occlusion.

Pituitary apoplexy. Hydrocortisone 100 mg IV then 50 mg IV every 6 hours, neurosurgical and endocrine referral, correction of sodium and fluid balance.

Hypertensive emergency and pre-eclampsia. Specialist care achieves controlled reduction of blood pressure. Use labetalol 20 mg IV bolus, then 20 to 80 mg every 10 minutes or infusion 0.5 to 2 mg/minute, reducing mean arterial pressure by no more than 25 percent in the first hour.

For pre-eclampsia with neurological signs, give magnesium sulphate 4 g IV over 5 to 15 minutes then 1 g/hour, with delivery planning by obstetrics.

Methanol poisoning. Fomepizole 15 mg/kg IV loading dose then 10 mg/kg every 12 hours for 4 doses (increase to 15 mg/kg every 12 hours thereafter), folinic acid 50 mg IV every 6 hours, bicarbonate for acidosis, and haemodialysis by toxicology and nephrology. Ethanol infusion when fomepizole is unavailable.

Endophthalmitis. Emergency vitreous tap and intravitreal vancomycin 1 mg and ceftazidime 2.25 mg by ophthalmology, with systemic antibiotics for endogenous infection.

Toxic optic neuropathy. Stop the drug (ethambutol, linezolid, amiodarone) after specialist advice.

Functional visual loss. Positive diagnosis through consistent testing, explanation, and psychological support after serious causes are excluded.

Monitoring. Visual acuity, fields and intraocular pressure at each ophthalmic review; blood pressure, glucose, blood count, and mood on high dose corticosteroids; imaging of the second eye risk in giant cell arteritis.

Referral and escalation. Immediate ophthalmology and stroke team for suspected artery occlusion. Same day rheumatology or specialist review for giant cell arteritis. Neurology for optic neuritis and central causes. Neurosurgery for chiasmal, pituitary and intracranial lesions. Cardiology and vascular surgery for embolic sources.

Admission criteria. Artery occlusion within the thrombolysis window, giant cell arteritis with visual loss, stroke, pituitary apoplexy, hypertensive emergency, endophthalmitis, orbital cellulitis, methanol poisoning, or retinal detachment awaiting surgery.

Discharge and safety netting. Return urgently for any new visual loss in either eye, flashes, curtain, pain, headache, double vision, jaw pain, or weakness. Advise against driving until the legal visual limits set by local rules are confirmed by ophthalmology.