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Preseptal and orbital cellulitis
The decisive distinction is where the infection lies relative to the orbital septum: preseptal cellulitis is confined to the eyelid and treated with oral antibiotics, while orbital cellulitis — with proptosis, limited movement, pain on movement or reduced vision — needs admission, contrast CT and intravenous antibiotics.
Why it matters in the exam
The distinguishing signs: in preseptal cellulitis there is lid swelling and redness, but eye movements are full and painless, there is no proptosis and vision and pupil responses are normal. In orbital cellulitis proptosis, limited and painful movements, conjunctival swelling (chemosis), reduced acuity or colour vision and an RAPD appear, with fever and a worse general state. The commonest source is ethmoid sinusitis, through the thin wall (lamina papyracea), mainly in children; other sources: trauma, insect bites, dental infection and lacrimal infection.
Contrast CT of the orbits and sinuses is needed when there is an orbital sign, when the eye cannot be examined because of swelling, or when the eye has not improved after 24–48 hours. Treatment of orbital cellulitis: broad-spectrum intravenous antibiotics (for example ceftriaxone with vancomycin, and metronidazole when anaerobes or intracranial infection are suspected), treatment of the sinuses and an ENT consultation. A subperiosteal abscess is drained when it is large, when vision is affected, when there is no improvement within 48 hours or in an older child; small abscesses in young children often respond to antibiotics alone.
The dangerous complications: cavernous sinus thrombosis (bilateral signs, palsies of nerves III, IV and VI, reduced consciousness), meningitis and brain abscess. In a diabetic with DKA or an immunosuppressed patient with black necrosis on the palate or nose — mucormycosis: amphotericin B and urgent surgical debridement. Vaccination against Haemophilus influenzae type b has greatly reduced orbital cellulitis in toddlers. In every admitted patient acuity, colour vision and pupils are checked several times a day, because deteriorating vision is the earliest sign that surgery is needed.
Key points
- The distinction: relative to the orbital septum.
- Orbital: proptosis, limitation, pain on movement, reduced vision.
- Common source: ethmoid sinusitis.
- Orbital → admission, CT, intravenous antibiotics.
- Complications: cavernous sinus thrombosis, brain abscess.
Summary table
| Feature | Preseptal | Orbital |
|---|---|---|
| Proptosis | None | Present |
| Eye movements | Full, painless | Limited and painful |
| Vision and RAPD | Normal | Reduced acuity and colour, possible RAPD |
| Common source | Skin wound, bite, stye | Ethmoid sinusitis |
| Treatment | Oral antibiotics, close follow-up | Admission, CT, intravenous antibiotics, drainage as needed |
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Sources
- AAO Basic and Clinical Science Course, Section 7: Oculofacial Plastic and Orbital Surgery, 2024-2025 — Orbital inflammatory and infectious disorders
- IDSA Clinical Practice Guideline for Acute Bacterial Rhinosinusitis in Children and Adults, 2012 — Orbital complications
- Kanski's Clinical Ophthalmology, 9th edition (2020) — Orbit
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.