Eye, red and tender

Probability diagnosis

Conjunctivitis:

• bacterial

• adenovirus

• allergic

Serious disorders not to be missed

Acute glaucoma

Uveitis:

• acute iritis

• choroiditis

Corneal ulcer

Corneal injury: abrasion/foreign body

Herpes simplex keratitis

Microbial keratitis (e.g. fungal, amoeba, bacterial)

Herpes zoster ophthalmicus

Penetrating injury

Endophthalmitis

Orbital cellulitis

Pitfalls (often missed)

Scleritis/episcleritis

Foreign body (esp. IOFB)

Trauma

Ultraviolet light ‘keratitis’

Blepharitis

Rarities:

• cavernous sinus arteriovenous fistula

• primary tumour of eye

Masquerades checklist

Drugs (hypersensitivity)

Thyroid disorder (hyperthyroidism)

Key history

The five essentials of the history are:

• history of trauma, especially as indicator of intraocular foreign body (IOFB)

• vision

• the degree and type of discomfort

• presence of discharge

• presence of photophobia.

Consider association with spondyloarthropathies.

Key examination

When examining the unilateral red eye keep the following diagnoses in mind:

• trauma

• foreign body, including IOFB

• corneal ulcer

• iritis (uveitis)

• viral conjunctivitis (commonest type)

• acute glaucoma

The four essentials of the examination are:

• testing and recording vision

• meticulous inspection under magnification (slit lamp is ideal)

• testing the pupils

• testing ocular tension

Key investigations

• May include swab of discharge for MC, visual acuity

• ESR/CRP

• HLAB27

• Consider specialist referral

Diagnostic tips

• A purulent discharge indicates bacterial conjunctivitis.

• A clear or mucus discharge indicates viral or allergic conjunctivitis.

• Be alert for the unilateral red eye: think beyond the conjunctivitis trio. It may be a corneal ulcer, keratitis, foreign body, trauma, uveitis or acute glaucoma.