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Describe papilloedema and the differential diagnosis of a swollen optic disc.

Ophthalmology · 3rd Professional

Papilloedema

Papilloedema is swelling of the optic disc caused by raised intracranial pressure.
The term should be reserved for that cause alone; other causes of a swollen disc are called optic disc swelling.
It is characteristically bilateral.

Sign	Detail
Blurring of the disc margins	Beginning nasally, then superior, inferior and last temporal — the reverse of the ISNT order, and a useful sequence to remember
Disc hyperaemia	With dilated surface capillaries; the disc looks pink and full
Loss of spontaneous venous pulsation	An early sign; but it is absent in 20% of normal people, so its absence proves nothing. Its presence, however, makes raised intracranial pressure unlikely, and that is the useful direction
Elevation of the disc	With filling of the physiological cup and blurring of the vessels as they cross the margin
PATON’S lines	Concentric retinal folds around the disc, from lateral displacement of the peripapillary retina; characteristic
Haemorrhages and cotton-wool spots	Flame haemorrhages at the margin, and exudates that may form a macular star
Chronic papilloedema	The disc becomes pale and "champagne cork" shaped, haemorrhages resolve, and optociliary shunt vessels and drusen-like bodies appear. Field loss becomes permanent
Atrophic (post-papilloedema) atrophy	Secondary optic atrophy with a dirty grey disc, indistinct margins and sheathed vessels; the vision is now irreversibly lost

The Differential Diagnosis of a Swollen Disc

Feature	Papilloedema	Papillitis
Laterality	Bilateral	Usually unilateral
Visual acuity	Normal until late	Markedly reduced, early
Afferent pupillary defect	Absent	Present
Colour vision	Normal	Markedly impaired — red desaturation
Field defect	Enlarged blind spot only, early	Central or centrocaecal scotoma
Pain	Headache, not ocular	Pain ON eye movement
Vitreous cells	Absent	Often present
Course	Resolves when the pressure is relieved	Recovers over weeks

Pseudopapilloedema must be excluded before any patient is investigated for raised pressure.
Optic disc drusen — calcified hyaline bodies. The disc is elevated with a lumpy, irregular margin but the cup is absent, there is NO hyperaemia, NO haemorrhage and NO obscuration of the vessels. Confirmed by autofluorescence, B-scan ultrasound showing calcification, or OCT. They may cause field defects but are benign
Small crowded hypermetropic disc — the commonest cause, in which the disc is simply small with no physiological cup
Myelinated nerve fibres — white feathery patches with a frayed edge continuous with the disc
Other causes of true disc swelling — ischaemic optic neuropathy (unilateral, altitudinal defect, sudden); malignant hypertension (with retinal changes); central retinal vein occlusion; diabetic papillopathy; infiltration by leukaemia, lymphoma or sarcoid; uveitis and posterior scleritis; and ocular hypotony
Papilloedema is axonal swelling, not vascular, caused by stasis of axoplasmic flow at the lamina cribrosa
Transient obscurations last seconds, not minutes, which separates them from amaurosis fugax and from migraine
A sixth nerve palsy is a false localising sign, arising from stretch over the petrous ridge rather than from a lesion there
Nasal blurring comes first, which is the reverse of the ISNT order and a useful sequence when the change is subtle
Present venous pulsation makes raised pressure unlikely, though its absence proves nothing since a fifth of normal people lack it
Monitor with perimetry, not acuity; the field is lost long before the central vision in chronic papilloedema
Chronic papilloedema causes permanent field loss, so the urgency lies in relieving the pressure rather than in watching the disc
Request MR venography in suspected IIH; venous sinus thrombosis mimics it exactly and needs anticoagulation instead
Weight loss is the definitive treatment for IIH, and produces sustained remission where drugs merely temporise
Ask about tetracyclines, retinoids and vitamin A, and about recent steroid withdrawal; each is a recognised precipitant
Fenestrate the nerve sheath for vision and shunt for headache; the two indications lead to different operations

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