AKT · Ophthalmology/Orbit & infection

Orbital cellulitis

Infection POSTERIOR to the orbital septum (usually from ethmoid sinusitis)

Overview

A sight- and life-threatening infection of the orbital tissues posterior to the septum, usually spreading from ethmoid sinusitis. Presents with a red swollen lid PLUS proptosis, painful/restricted eye movements (ophthalmoplegia), and reduced vision/colour. An emergency: admit for IV antibiotics and CT; complications include abscess, cavernous sinus thrombosis, meningitis and blindness.

Recognise

Red, swollen, painful eyelid WITH proptosis, painful and RESTRICTED eye movements (ophthalmoplegia), and diplopia
Reduced visual acuity and colour vision, RAPD; chemosis; systemically unwell with fever
Usually from ethmoid sinusitis (lamina papyracea is thin); commoner in children

Red flags

Reduced vision/colour, RAPD, or proptosis = optic-nerve threat — emergency
Headache, cranial-nerve palsies, bilateral signs, reduced consciousness → cavernous sinus thrombosis/intracranial spread
Diabetic/immunocompromised with black necrotic eschar in nose/palate → MUCORMYCOSIS (rhino-orbital) — emergency antifungals + debridement

Differentials & how to tell them apart

Preseptal cellulitisNORMAL eye movements/vision/colour, NO proptosis — anterior to the septum, oral antibiotics

Cavernous sinus thrombosisbilateral signs, multiple cranial-nerve palsies, severe headache — orbital cellulitis can cause it

Rhino-orbital mucormycosisdiabetic/immunocompromised with black necrotic tissue — needs antifungals + surgery

Thyroid eye disease / orbital pseudotumourless acute, afebrile; TED is often bilateral with lid retraction

Orbital cellulitis — lid swelling, erythema and proptosis
Jonathan Trobe, M.D. / CC BY 3.0 — Wikimedia Commons

Investigations

Urgent CT (or MRI) of orbits and sinuses (subperiosteal/orbital abscess, sinusitis). Bloods/cultures, assess vision/colour/pupils. Blood glucose (exclude diabetes/immunosuppression).

Management

Admit + IV broad-spectrum antibiotics + urgent CT (drain abscess; ENT/ophthalmology)

1EMERGENCY admission. IV broad-spectrum antibiotics (e.g. ceftriaxone + metronidazole), urgent CT orbits/sinuses, and joint ophthalmology/ENT care. Monitor vision, colour and pupils frequently.Gate: Reduced vision/colour, RAPD, an abscess on CT, or intracranial spread → urgent surgical drainage; in a diabetic/immunocompromised patient with necrotic tissue, treat as MUCORMYCOSIS (antifungals + debridement), not bacterial cellulitis
2Abscess/non-responding → surgical drainage of the orbit/sinuses; treat complications (cavernous sinus thrombosis, meningitis); manage the source sinusitis.

IV broad-spectrum antibiotics — e.g. ceftriaxone + metronidazole (cover sinus organisms incl. anaerobes); per local policy

Surgical drainage — for orbital/subperiosteal abscess or sinus drainage (ENT)

Antifungals (amphotericin) + debridement — if mucormycosis

Key points

Lid swelling + proptosis + painful restricted eye movements + reduced vision = orbital cellulitis = admit now. The pair with preseptal is THE classic discriminator. In the diabetic, think mucormycosis.

Monitor & prognosis

Frequent vision/colour/pupil checks; repeat imaging if not improving.

Good with prompt IV antibiotics; delay risks blindness and intracranial spread.

Source: RCOphth; NICE; ENT UK