Conjunctivitis
Conjunctivitis can be viral, bacterial or allergic. Bacterial and especially viral conjunctivitis are often highly contagious. As a general rule, purulent discharge indicates bacterial conjunctivitis and a clear or mucous discharge indicates viral or allergic conjunctivitis. The presence of pruritis, a history of atopy and exposure to a known allergen usually helps to differentiate allergic conjunctivitis from viral.
Bacterial conjunctivitis is usually caused by Streptococcus pneumoniae, Haemophilis influenzae, Staphylococcus aureus or Moraxella catarrhalis. Less commonly, Chlamydia trachomatis or Neisseria gonorrhoeae may be the causative organism.
Symptoms are similar to viral conjunctivitis, but discharge is usually mucopurulent and may cause the eyelids to become “glued” together after sleeping.
Symptoms are usually more severe and persistent in patients with conjunctivitis caused by Chlamydia trachomatis or Neisseria gonorrhoeae (termed hyperacute conjunctivitis).
Bacterial conjunctivitis is self-limiting in most people and symptoms resolve without treatment within one to two weeks (although resolution may be more rapid in some people). Advise supportive treatment (as for viral conjunctivitis). Avoid the use of cosmetics applied to the eye area as these may be contaminated.
There has been much debate as to whether the use of topical antibiotics improves recovery time in people with bacterial conjunctivitis. A 2012 Cochrane review of 11 randomised controlled trials concluded that the use of antibiotic eye drops for bacterial conjunctivitis modestly improved the rate of “clinical and microbiological remission” and was associated with a low risk of serious adverse effects. The meta-analysis found that after five days, symptoms had resolved in 30% of patients receiving placebo and in 40% of those receiving a topical broad-spectrum antibiotic. By day ten there was 41% remission in the placebo group and 50% remission in the antibiotic group.
Most patients (or parents of young patients) who present to general practice with bacterial conjunctivitis will expect to receive topical antibiotic treatment. The limitations of treatment should be explained and, if appropriate, offer a “back pocket prescription” and instruct the patient (or parent) to delay starting treatment for a few days to see if the symptoms resolve. Antibiotics may be started immediately if symptoms are severe or distressing. The recommended treatment for adults and children aged over two years is chloramphenicol 0.5% eye drops, one to two drops, every two hours for the first 24 hours, then every four hours, until 48 hours after symptoms have resolved. Chloramphenicol 1% eye ointment can also be used at night in patients with severe infections or as an alternative to eye drops for those who prefer this formulation. Fusidic acid 1% eye gel is an alternative to chloramphenicol, and is preferred in women who are pregnant; one drop, twice daily, until 48 hours after symptoms have resolved.
Viral conjunctivitis is usually caused by an adenovirus. Typical features are sequential bilateral red eyes, watery discharge and inflammation around the eye and eyelids, which can produce dramatic conjunctival swelling (chemosis) and lid oedema, to the extent that the eye is swollen shut. The patient usually reports a feeling of grittiness or stabbing pain, and may also have rhinorrhoea or other respiratory symptoms. Crusting of the lashes overnight can sometimes be confused for a purulent discharge. Enlarged, tender preauricular lymph nodes are often present, and are a useful feature to assist diagnosis.
As there is no effective viricidal treatment against adenovirus, viral conjunctivitis is treated supportively. Advise the patient to clean away secretions from eyelids and lashes with cotton wool soaked in water, wash their hands regularly, especially after touching eye secretions, avoid sharing pillows and towels and avoid using contact lenses. Artificial tear eye drops can be used if necessary to reduce discomfort.
Symptoms may take up to three weeks to resolve. In severe cases, punctate epithelial keratitis may develop – this can be seen with fluorescein staining as multiple small erosions of the conjunctiva. Patients with this complication may report ongoing discomfort for several weeks, which then resolves spontaneously. Immune sub-epithelial infiltrates may develop after the conjunctivitis has settled, impairing visual acuity. These cannot be seen with fluorescein dye, and can take several weeks to resolve spontaneously.
Allergic conjunctivitis is caused by a local response to an allergen, e.g. pollen, preservatives in eye drops or contact lens solution. Patients typically present with swollen, itching eye(s), irritation, mild photophobia and watery or serous discharge. Symptoms are episodic in the case of seasonal allergies. Eversion of the lids often reveals a “cobble-stone” appearance of the tarsal (eyelid) conjunctiva because of the development of large papillae or swellings of the subepithelial stroma (connective tissue).
Treatment is supportive; avoid the allergen where possible, avoid rubbing the eyes, apply a cool or warm compress to relieve symptoms, use artificial tear eye drops if required. If symptoms are severe or other treatments are ineffective, prescribe antihistamine eye drops, e.g. levocabastine, or a mast cell stabiliser (takes several weeks for full effect), e.g. lodoxamide or cromoglicate sodium. Olopatadine eye drops combine antihistamine and mast cell stabilisation activity and are often effective. An oral antihistamine may also be prescribed, depending on patient preference and previous response to treatment.
Patients with severe allergic conjunctivitis should have their visual acuity checked and a fluorescein examination, and then be referred to an Ophthalmologist for further assessment and possible initiation of topical corticosteroids. Vernal and atopic keratoconjunctivitis are two severe forms of allergic eye disease affecting children and young adults respectively, and can be associated with large epithelial defects on the cornea (shield ulcers) that can lead to scarring, and also microbial keratitis – especially if topical immunosuppressants are being used.
There is also a range of medicines that may help. Some are available over the counter at the pharmacy and other stronger medicines need a prescription.
Antihistamine tablets work in the same way as the eye drops, but will also treat other allergy symptoms such as a runny nose and sneezing that is caused by the allergy.
You should not wear contact lenses if your symptoms are severe or if you have been told that your cornea is affected. Do not put drops in your eyes while wearing contact lenses.
Occasionally you may need to be referred to an allergy specialist if the condition does not get better with treatment or the symptoms are very severe, but this is rare.