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.
Conjunctivitis caused by viral infection is sometimes called "pink eye", although this term is sometimes used for all forms of conjunctivitis. Viral conjunctivitis is highly contagious.
What causes viral conjunctivitis?
Viral conjunctivitis may be due to systemic or localised infection.
Viral conjunctivitis is typically caused by a systemic infection by adenovirus, and is associated with respiratory tract symptoms. It can also be due to local infection by herpes simplex, herpes varicella zoster virus (cause of chickenpox and shingles), picornavirus (enterovirus 70, coxsackie A 24), poxvirus (molluscum contagiosum) and human immunodeficiency virus.
What are the symptoms and signs of viral 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 stye or blepharitis)
The following "red flags" point to other more serious diagnoses, such as keratitis (inflammation of the cornea), 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
Pointers to a systemic viral cause of conjunctivitis include:
- Involvement of first one eye then the second within 24 to 48 hours
- Injection of the conjunctiva (ie fine blood vessels that give a generally red appearance to the eye)
- Watery discharge during the day — mucus rather than pus
- Lack of pus at the lid margin or in the corners of the eye (unlike bacterial conjunctivitis)
- Burning, sandy, or gritty feeling
- A bumpy appearance of the tarsal conjunctiva (under the eyelids)
Epidemic keratoconjunctivitis (EKC) is a fulminant form of viral conjunctivitis and keratitis. Features include:
- A sensation of a foreign body
- Multiple corneal infiltrates
- Inability to open the eyes spontaneously
- Loss of visual acuity
These more serious infections may threaten vision.
Herpes simplex infection (HSV) should be suspected in young children with follicular conjunctivitis. Herpes simplex infection can also cause keratitis, blepharitis, and iritis. It is associated with enlarged and tender preauricular lymph node. The presentation of other viral forms of conjunctivitis depends on the specific virus.
What are the complications of viral 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 viral conjunctivitis include:
- Bacterial conjunctivitis
- Chronic redness, discharge and irritation
How is viral conjunctivitis treated?
Viral conjunctivitis is a self-limited process. The clinical course of the systemic form of viral conjunctivitis parallels that of the common cold. Symptoms often worsen for 3–5 days, with gradual resolution over 1–2 weeks.
Symptomatic treatments include:
- Cold compresses several times per day
- Lubricant eye drops
- Topical vasoconstrictors (eg phenylephrine 0.12% drops)
- Systemic analgesics for pain relief
Severe cases may require hospitalisation for systemic and topical treatments.
Patients should be educated about hygiene measures to reduce the spread of the infection.
- Wash hands often
- Avoid touching or rubbing eyes
- Wash discharge from around the eyes using a fresh cotton ball or tissue
- Discard used make-up, contact lens solution and used disposable contact lenses
- Wash bed linen and towels in hot water and detergent
- Avoid sharing cosmetics, bed linen, towels and clothing
- Avoid swimming in a public swimming pool