Optic Disc Swelling

Elevation and blurring of the optic nerve head. It is a sign with many causes, and distinguishing true swelling from pseudo-swelling and papilloedema (swelling from raised intracranial pressure) from other causes is the main challenge.

• Causes of true swelling:
  • Raised intracranial pressure (papilloedema): bilateral, from tumour, idiopathic intracranial hypertension, cerebral venous thrombosis, hydrocephalus, meningitis, and haemorrhage.
  • Optic nerve inflammation: optic neuritis (papillitis), neuroretinitis (macular star), sarcoid, infectious (syphilis, Lyme, cat-scratch), and perineuritis.
  • Ischaemia: anterior ischaemic optic neuropathy, central retinal vein occlusion, diabetic papillopathy, and malignant hypertension.
  • Compressive and infiltrative: optic nerve sheath meningioma, glioma, thyroid eye disease, lymphoma, and leukaemia.
  • Metabolic and toxic: hypotony, uveitis, vitamin A toxicity, and drugs (amiodarone, tetracyclines, lithium).
• Pseudo-swelling: optic disc drusen (buried), tilted disc, hypermetropic crowded disc, myelinated nerve fibres, and congenital anomalies.

• Symptoms vary: none (pseudo-swelling, early papilloedema), transient visual obscurations lasting seconds (papilloedema), headache, nausea and pulsatile tinnitus (raised pressure), and pain on eye movement with reduced acuity and colour vision (optic neuritis).
• Signs of true swelling: hyperaemia, blurred disc margins, obliteration of the cup, vessels obscured at the disc margin, venous engorgement, peripapillary haemorrhages (flame), cotton wool spots, exudates, and hard exudate star at the macula (neuroretinitis).
• Papilloedema: bilateral, preserved acuity and colour vision early, enlarged blind spot, no relative afferent pupillary defect, and later constricted fields.
• Optic neuritis: unilateral, acuity loss, afferent defect, central scotoma, and pain.
• Ischaemic: sudden, altitudinal, afferent defect; central retinal vein occlusion: dilated tortuous veins and widespread haemorrhages.
• Pseudo-swelling: no haemorrhage, no obscuring of vessels, visible peripapillary vessels, and refractile bodies (drusen).

• Visual acuity, colour vision, pupils, fields, dilated fundus examination of both eyes, blood pressure, and neurological examination.
• Optical coherence tomography of the retinal nerve fibre layer (thickened in true swelling) and optic disc morphology; enhanced depth imaging for drusen; fundus autofluorescence (drusen autofluoresce); B-scan ultrasound (calcified drusen); fluorescein angiography (leakage in true swelling, none in pseudo-swelling).
• Urgent MRI and MR venography (or CT venography) of the brain when papilloedema is suspected, with lumbar puncture and opening pressure after imaging when there is no mass (normal pressure up to 25 cmH2O in adults); MRI orbits when unilateral without clear cause.
• Blood tests: blood pressure, full count, ESR, CRP, glucose, syphilis serology, Bartonella and Lyme serology, ACE, antibodies (aquaporin-4, myelin oligodendrocyte glycoprotein), and coagulation and thrombophilia screens.

• Treat the cause and triage urgency: swelling with raised intracranial pressure and papilloedema needs same-day imaging; true swelling with acute visual loss and pain needs rapid assessment for giant cell arteritis and inflammatory disease.
• Raised intracranial pressure: head elevation, dexamethasone 4 mg every 6 hours for tumour oedema, acetazolamide 250 to 500 mg twice daily for idiopathic intracranial hypertension, and neurosurgical care.
• Optic neuritis: intravenous methylprednisolone 1 g daily for 3 to 5 days; ischaemic: management by cause (steroids for arteritic); compressive: decompression and tumour therapy; neuroretinitis: treat the infection (doxycycline 100 mg twice daily for 4 to 6 weeks for Bartonella).
• Malignant hypertension: reduce blood pressure steadily (labetalol, nicardipine) and avoid precipitous falls.
• Pseudo-swelling: reassure, document baseline images, and monitor for complications of drusen (visual field loss, haemorrhage, anterior ischaemic optic neuropathy).
• Monitor fields and nerve fibre layer thickness at 1 to 3 month intervals until the swelling resolves, and evaluate for optic atrophy.