• Common causes of a red eye include conjunctivitis (viral, bacterial, allergic or chemical), foreign body, corneal ulceration and subconjunctival haemorrhage.
• Uncommon causes include iritis, scleritis, episcleritis and glaucoma.
• A discharging non-red eye in infants is most likely due to nasolachrymal duct obstruction.

Assessment

Obtain a history concentrating on the possibility of ocular trauma, contact lens wear, time course of the redness, and the presence of eye pain, itch and discharge.

Eye examination

• Carefully inspect eyelids, everting to examine the undersurface.
• Examine the conjunctiva, pupil, iris and cornea, using the slit lamp whenever possible.
• Stain with fluroscein if corneal abrasion or ulcer possible.
• If trauma is possible examine for enophthalmos, diplopia, subconjunctival haemorrhage, hyphema and retinal detatchment.
  (See penetrating eye injury guidelines)

• Always measure the visual acuity with age-appropriate charts.

Signs and symptoms	Diagnoses to be considered
pain, photophobia, watery discharge	- foreign body - traumatic corneal ulcer - herpetic ulcer - acute glaucoma
purulent discharge	- infective conjunctivitis
itchiness, eyelid swelling and redness, watery discharge	- allergic conjunctivitis
dull, aching eye pain	- iritis, scleritis, episcleritis
subconjunctival haemorrhage	- trauma - vigorous coughing or vomiting
focal conjunctival injection or iris injury	- trauma

Conjunctivitis (non neonatal)

• May be difficult to clinically differentiate bacterial, viral and allergic conjunctivitis.
• Suspect bacterial conjunctivitis if purulent discharge. Treat with eye toilet and topical chloramphenicol.
• Suspect herpes simplex infection if lid vesicles. If a dendritic ulcer is present treat with acyclovir ointment and contact ophthalmology.
• Suspect allergic conjunctivitis if bilateral watery discharge with burning or itchy sensation and eyelid swelling, especially in an atopic child. Consider treating with antihistamines (oral or topical) and artificial tears.
• Chloramphenicol eye drops can cause contact hypersensitivity reactions; if a hypersensitivity reaction is suspected, cease chloramphenicol and seek advice from an ophthalmologist.
  

Conjunctivitis (neonatal)

• Pathogens include staphylococcus, haemophilus, chlamydia, streptococcus, gonococcus and herpes simplex..
• Obtain conjunctival scrapings for gram stain, giemsa stain and cultures.
• Use chlamydia kit for immmunofluorescence and treat chlamydial conjunctivitis with eye toilet and oral erythromycin.
• Consider gonococcal conjunctivitis if severe purulent discharge with conjunctival and lid oedema. Perform an urgent gram stain and contact ophthalmology þ may need septic work up and systemic Ceftriaxone 50 mg/kg/dose (2g) iv 12H.
• Treat other organisms with topical chloramphenicol.

Foreign body

• Anaesthetise conjunctiva with amethocaine 1% or benoxinate 0.4%. (one drop).
• Examine surface of eye and under lids, using slit lamp if possible.
• Stain with fluroscein to assess corneal injury.
• Remove foreign body with moistened cotton bud, apply chloramphenicol ointment and pad for four hours.
• Need daily review until epithelium healed.
• Refer embedded or metallic foreign bodies to ophthalmologist.

Corneal ulceration

• May be caused by trauma (including foreign body) or herpes simplex infection.
• Visible after fluroscein staining.
• If traumatic apply chloramphenicol ointment and review in 24 hours.
• If dendritic ulcer contact ophthalmology.

Chemical burns

• Irrigate eye with copious amounts of saline for at least 15 minutes, until pH normal.
• Particulate alkaline matter must be totally removed (may require GA).
• Assess damage with fluroscein staining and slit lamp examination þ if corneal damage contact ophthalmology.

Iritis

• Presents with pain, photophobia, blepharospasm and lacrimation.
• Pupil may be small and poorly reactive.
• May occur in association with juvenile chronic arthritis.
• Contact ophthalmology.

Scleritis and episcleritis

• Present with localised areas of inflammation with tenderness and lacrimation.
• Strongly associated with systemic disease.
• Contact ophthalmology.

Glaucoma

• Presents with an enlarged, hazy cornea, photophobia and lacrimation.
• Contact ophthalmology

Trauma

• Consider if hyphema or focal conjunctival injection.
• Consider penetrating injury (see penetrating eye injury guidelines).
• Contact ophthalmology.