👁️ Chemosis (Conjunctival oedema)

🧠 Chemosis = swelling/oedema of the conjunctiva (often looks like “jelly” or ballooning around the cornea). Pathophysiology is usually either ↑ vascular permeability (allergy/inflammation/infection) or venous/lymphatic congestion (orbital pressure, thyroid eye disease, impaired venous drainage). The key clinical skill is spotting the few dangerous causes where chemosis is a marker of orbital pathology rather than simple conjunctivitis.

✅ First assessment (always)

• 📌 Check vision (acuity), pupils (RAPD), and pain level.
• 👀 Look for proptosis, reduced eye movements, diplopia, corneal exposure, photophobia.
• 🌡️ Ask about fever, sinus symptoms, trauma/surgery, contact lenses, anaphylaxis symptoms.
• 🧪 If discharge: watery vs mucopurulent; consider fluorescein if pain/photophobia/contact lenses (corneal involvement).

🚨 Red flags (same-day urgent ophthalmology / ED)

• 🔻 Reduced visual acuity or RAPD
• 😖 Severe pain, marked photophobia, or headache
• 👁️‍🗨️ Proptosis, restricted eye movements, diplopia
• 🌡️ Fever/toxicity, sinusitis + eye signs (think orbital cellulitis)
• 🩸 Recent facial/orbital trauma or eye surgery (think retrobulbar haemorrhage)
• 🧪 Chemical splash / alkali injury
• 🦠 Copious purulent discharge + rapid swelling (think gonococcal infection)

🧩 Causes of chemosis

• 🌼 Allergic conjunctivitis (itching, watery discharge, lid swelling; often bilateral)
• 🦠 Viral conjunctivitis (gritty, watery, contagious; pre-auricular nodes)
• 🧫 Bacterial conjunctivitis (mucopurulent discharge, lids stuck; usually mild)
• 🦠 Chlamydial conjunctivitis (chronic redness/discharge; follicular changes)
• ☣️ Severe hyperacute conjunctivitis (e.g., gonococcal) — can cause dramatic chemosis
• 🧠 Orbital cellulitis / post-septal infection (chemosis + proptosis + painful/restricted EOM)
• 🩸 Trauma / post-op swelling; retrobulbar haemorrhage (time-critical vision threat)
• 🦋 Thyroid eye disease (exposure, lid retraction, proptosis; chemosis from congestion)
• 🧠 Venous outflow obstruction (e.g., cavernous sinus thrombosis, carotid–cavernous fistula, SVC obstruction)
• 😮‍💨 Angioedema/anaphylaxis (rapid onset lid/conjunctival swelling + systemic features)
• 🌙 Exposure/lagophthalmos (dryness + conjunctival oedema, especially overnight)

💊 Management (practical approach)

1) If red flags → urgent escalation

• 📞 Same-day ophthalmology/ED if any red flags (vision threat/orbital disease).
• 🧠 Suspected orbital cellulitis/CST: treat as emergency (IV antibiotics + imaging per local pathway).
• 🩸 Suspected retrobulbar haemorrhage: emergency decompression pathway (do not delay).
• 🧪 Chemical injury: immediate irrigation + urgent ophthalmology.

2) If uncomplicated (no red flags) → treat the common causes

🌼 Allergic chemosis

• 🧊 Cold compresses; avoid rubbing (rubbing worsens mast-cell mediator release).
• 💧 Lubricants (preservative-free artificial tears) regularly.
• 🧪 Topical antihistamine/mast-cell stabiliser drops (e.g., olopatadine/cromoglicate depending on local formulary).
• 💊 Oral non-sedating antihistamine if systemic allergy symptoms.
• 🧑‍⚕️ If severe/persistent: consider short supervised course topical steroid only with ophthalmology input (risk of HSV/glaucoma).

🦠 Viral conjunctivitis

• 💧 Lubricants + cold compresses; hygiene advice (handwashing, avoid sharing towels).
• 🚫 Avoid routine antibiotics (usually self-limiting).
• 🚩 If significant photophobia/pain or reduced vision: consider keratitis → urgent eye review.

🧫 Mild bacterial conjunctivitis

• 🧼 Lid hygiene, warm compress if crusting.
• 💊 Consider topical antibiotic if marked purulence, contact-lens wearer, or not improving (local formulary e.g., chloramphenicol).
• 🧴 Stop contact lenses until fully resolved; replace lenses/case to prevent reinfection.

🦠 Chlamydial / hyperacute (gonococcal) suspicion

• 📞 Same-day sexual health/ophthalmology advice.
• 💉 Gonococcal eye infection is an emergency (systemic therapy + urgent ophthalmology; corneal perforation risk).

🦋 Thyroid eye disease / exposure-related chemosis

• 💧 Aggressive lubrication (drops by day, ointment at night), consider taping lids closed overnight if exposure.
• 🚭 Smoking cessation (major modifiable risk factor for TED severity).
• 🧑‍⚕️ Refer to ophthalmology/TED service if proptosis, diplopia, pain, or corneal exposure.

🏠 Patient advice

• ✅ Seek urgent help if vision worsens, pain increases, new diplopia, or swelling rapidly progresses.
• 🧼 Avoid rubbing; wash hands; don’t share towels/makeup.
• 👓 Avoid contact lenses until symptoms fully settle.

🔑 Clinical pearl: chemosis is a sign, not a diagnosis. The “big divider” is whether there are features of orbital disease or vision compromise. If the eye is painful, proptosed, movement-limited, febrile, or vision is reduced, treat it as urgent until proven otherwise.