2. Infectious conjunctivitis
Infective conjunctivitis can be caused by several bacterial and viral pathogens. Infective conjunctivitis can be further differentiated into acute infective conjunctivitis, defined as inflammation of the conjunctiva due to infection that does not last longer than 3 weeks, and chronic conjunctivitis, inflammation of the conjunctiva that lasts longer than 3 weeks.
In the developed world, acute infectious conjunctivitis is a common presentation in the primary care setting, accounting for up to 2% of consultations with the general practitioner [ 2]. Many general practitioners find it difficult to differentiate between bacterial and viral conjunctivitis. The uncertainty of the pathogenic cause of acute conjunctivitis has led to the routine practice of prescribing a broad spectrum antibiotic topically even though the pathogen has not been proved to be bacterial in nature. In the UK, approximately 3.4 million topical antibiotic prescriptions are issued every year, at a cost to the NHS of over £4.7 million [3].
A diagnosis of conjunctivitis is usually made on the basis of a clinical history and examination by the clinician. Other investigations of conjunctivitis, such as swabs and cultures of the conjunctiva are rarely performed as it often delays treatment and has very little prognostic benefit, as conjunctivitis is often a self limiting illness and the antibiotics currently used have a good spectrum of pathogen coverage. Swabs and cultures are mainly used in research purposes.
It is vital that a correct diagnosis is made to early to identify the cause and start treatment promptly. It is also essential to rule out more serious causes and medical emergencies that would require hospital admission. Such cases would include bacterial keratitis, acute closed angle glaucoma, corneal abrasions and others.