What is conjunctivitis?
Conjunctivitis is inflammation of the conjunctiva of the eye.
The conjunctiva is the semi-transparent membrane that covers the white part of the eye (the sclera) and lines the inside of the eyelids.
When the conjunctiva is inflamed, the white of the eye appears red. Conjunctivitis is the most likely diagnosis when a patient has a red eye and discharge.
Irritant conjunctivitis is a non-infectious form of conjunctivitis caused by a transient mechanical or chemical insult. It can be acute, relapsing or chronic.
What causes irritant and traumatic conjunctivitis?
Irritant and traumatic conjunctivitis are associated with:
- Dry eye — whatever its cause
- Chemical splash (acid, alkali)
- Foreign body — redness and discharge may persist for 12 to 24 hours after the foreign body has been spontaneously expelled
- Eye irrigation — mechanical irritation
- Abrasions and blunt trauma.
Irritation is considered minor (eg, from swimming pool chlorination or noxious fumes), whereas chemical splash or traumatic conjunctivitis is often more serious.
What are the symptoms and signs of conjunctivitis?
Conjunctivitis is a diagnosis of exclusion. All forms of conjunctivitis are characterised by:
- Redness and discharge in one or both eyes
- Diffuse redness around the globe including the underside of the upper and lower lids
- Adhesion of the upper and lower eyelids on waking
- Normal vision
- Absence of focal pathology (eg, a stye or blepharitis).
Severe injury to the eye can involve the cornea (keratitis) or result in penetration of the orbit. The following 'red flags' point to more serious diagnoses, such as keratitis, iritis, or angle closure glaucoma:
- Changes in visual acuity
- Ciliary flush: A pattern of injection in which the redness is most pronounced in a ring at the limbus (the border of the cornea and the sclera)
- Photophobia (light sensitivity)
- Severe foreign body sensation that prevents the patient from keeping the eye open
- Corneal opacity
- Fixed pupil
- Severe headache with nausea
- A unilateral red eye.
Irritant or traumatic conjunctivitis can be suspected when:
- The discharge is more mucus than pus (tears)
- There is a history of dry eye, exposure to an irritant, eye irrigation after a chemical splash, or a foreign body in the eye
- The lower conjunctival sac is affected more than the upper (splash injury).
Symptoms of irritant or traumatic conjunctivitis generally improve spontaneously within 24 hours.
What are the complications of conjunctivitis?
Most forms of conjunctivitis are self-limiting but in certain cases, severe complications may occur. Pain, loss of vision or photophobia require immediate referral to an ophthalmologist.
Complications from irritant or traumatic conjunctivitis include:
- Chronic redness, discharge and irritation
How is an irritant or traumatic conjunctivitis treated?
Irritant or traumatic conjunctivitis often require only symptomatic relief, such as topical lubricants, and clear within 24 hours.