aka Ophthalmology Befuddler 002
Things are humming along nicely in the ‘Fast track’ area of the emergency department. You check the triage note of the next patient – RED EYE is written capitals.
Q1. There are many causes of ‘red eye’ — how can they broken down as an approach to diagnosis and management?
Of course there are myriad ways of doing this. I like Jeff Mann’s approach — he has a simple way of breaking the causes down into 3 groups:
- extra-ocular causes
(e.g. orbital cellulitis, cavernous sinus thrombosis, carotid-cavernous fistula, cluster headache)
- external eye disease
(e.g. eye lid and conjunctival disease)
- internal eye disease
(e.g. iritis, glaucoma)
Once an extra-ocular cause is excluded (this will be discussed in a later post), a helpful approach is to divide up the causes of red eye as follows:
- Painless — is there diffuse or localised redness?
The next step is to consider which structures are abnormal:
- Lid, conjunctiva, cornea, sclera, or anterior chamber?
This approach gets you off to a good start in narrowing down the causes of a red eye.
Q2. What are the causes of a painless red eye?
These can be classified according to whether the redness is diffuse or localised.
- diffuse —
usually this is an eyelid abnormality as most cases of conjunctivitis are painful: e.g. blepharitis, ectropion, trichiasis, entropion, eyelid lesion (e.g. tumour, stye)
- localised —
e.g. pterygium, corneal foreign body, ocular trauma, subconjunctival hemorrhage
If you’re stuck for a differential diagnosis, fall back on working through the anatomical components of the eye and running through a pathophysiological sieve.
Q3. What are the causes of a painful red eye?
These can be classified according which structure is abnormal:
- abnormal cornea —
e.g. herpes simplex keratitis, corneal ulcer, marginal keratitis, corneal abrasion,
- abnormal eyelid —
e.g. chalazion/ stye, acute blepharitis, herpes zoster ophthalmicus
- diffuse conjunctival injection —
e.g. viral conjunctivitis, allergic conjunctivitis, bacterial conjunctivitis, dry eyes, acute glaucoma
- ciliary injection/ scleral involvement —
- anterior chamber involvement —
e.g. acute anterior uveitis (iritis), hypopyon, hyphema
Q4. What 4 features usually suggest an internal cause of a red eye?
- severe eye pain (unrelieved by topical anesthetics)
- impaired vision
- poorly reactive pupils
- abnormal slit lamp examination +/- abnormal intra-ocular pressure
Q5. What 6 features on history and exam suggest an external cause for red eye?
- pain sensation is usually itching, gritty, scratching, or burning
(not a deep-seated ache)
- pain is significantly improved by topical anesthetics
- eye discharge is common
(watery, mucoid or purulent depending on etiology)
- photophobia and blepharospasm may be present
- visual acuity is usually normal or near-normal
(there may be some blurriness)
- preauricular lymphadenopathy may be present
(e.g. viral or chlamydial conjunctivitis)
Q6. What 7 features on exam should be present if the cause of a red eye is not serious?
- cornea clear
- anterior chamber clear
- pupils normal in size and reactivity
- visual acuity normal or near-normal
- extraocular eye movements normal
- proptosis absent
- eyeball is not tender on palpation
Q7. What is the likely diagnosis of a red eye in a middle-aged woman with the following findings?
- mid-dilated unreactive pupil, steamy cornea, peri-orbital pain , nausea/vomiting and increased intra-ocular pressure
angle closure glaucoma
- small irregular pupil, deep-seated eye pain that is worse on eye movement and accomodation, consensual photophobia and positive slit lamp signs of flare and cells
- deep-seated eye pain that is worse at rest and at night, pain on palpation of the eye and violaceous appearance of the sclera
- proptosis, congested chemosis, painful external ophthalmoplegia, and visual loss with a relative afferent pupillary defect
orbital cellulitis or cavernous sinus venous thrombosis
Q9. What potentially serious causes of a red eye are suggested by the following features on history or examination?
- Severe eye aching
Iritis, keratitis, acute angle-closure glaucoma, scleritis, orbital cellulitis, cavernous sinus thrombosis (CST)
- Prominent photophobia
- Impaired vision
Iritis, keratitis, acute angle-closure glaucoma, orbital cellulitis, CST
- Cloudy cornea
Keratitis, acute angle-closure glaucoma
- Corneal opacification
Keratitis – chemical or infectious
- Circumcorneal conjunctival injection
- Cloudy anterior chamber
- Pain on eyeball palpation
Scleritis (+++), orbital cellulitis, CST
Orbital cellulitis, CST, posterior scleritis
- Impaired, or painful, extraocular eye movements
- Fever, toxic appearance
Orbital cellulitis (+), CST (++)
- Hyperpurulent discharge from an “angry” eye
- Prominent nausea and vomiting
Acute angle-closure glaucoma
- Small, irregular, poorly-reactive pupil
- Fixed mid-dilated pupil
Acute angle-closure glaucoma
- Increased intra-ocular pressure
Acute angle-closure glaucoma, iritis (secondary complication)
- History of connective tissue disease, or granulomatous disease
- Ehlers JP, Shah CP, Fenton GL, and Hoskins EN. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease (5th edition). Lippincott Williams & Wilkins, 2008.
- Jeff Mann’s EM Guidemaps. Red eye. [many of the Q&A's in this post are a rearrangement of the major learning points from this web page]
- Mahmood AR, Narang AT. Diagnosis and management of the acute red eye. Emerg Med Clin North Am. 2008 Feb;26(1):35-55, vi. PMID: 18249256.
- Marx JA, Hockberger R, Walls RM. Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th edition (2009) Mosby, Inc. [mdconsult.com]
- NSW Statewide Opthalmology Service. Eye Emergency Manual — An illustrated Guide, 2007. [link to free pdf]