Conjunctivitis, also known as pink eye, is an inflammation of the outermost layer of the white part of the eye and the inner surface of the eyelid. Itching of the eye is more common in cases due to allergies. Conjunctivitis can affect one or both eyes. The most common infectious causes are viral followed by bacterial.
Viral conjunctivitis is an infection of the eye in which one or both eyes become red and uncomfortable. The condition is not normally serious and in most cases clears up without treatment. However, it is highly infectious and care needs to be taken to prevent others from becoming infected, for example by not sharing towels.
In terms of treatment, antibiotics are ineffective against viruses and there is no effective anti-viral drug. Usual care involves the control of symptoms using cool compresses applied to the closed eyes, coupled with the use of lubricating eye drops. In a small number of cases viral conjunctivitis can lead to the development of small opaque areas within the cornea (the clear window at the front of the eye), which can impact on vision. In such cases urgent referral to an ophthalmologist should be arranged.
Acute bacterial conjunctivitis is an infection of the eye in which one or both eyes become red with associated discomfort. The condition is not normally serious and in most cases, clears up without treatment. People with acute conjunctivitis are often given antibiotics, usually in the form of eye drops or ointment, to speed recovery.
However, the benefits of antibiotics for the treatment of bacterial conjunctivitis have been questioned. A review of randomised clinical trials comparing antibiotic eye drops to placebos concluded that antibiotics can speed up the resolution of acute conjunctivitis. However, the benefits are less clear when the results of trials conducted exclusively in community GP practices are considered, since these patients tend to have a less severe form of conjunctivitis than would be expected in hospital practice.
Acute allergic conjunctivitis is an allergic reaction of the eyes, which causes a sudden swelling and redness of the eyelids and conjunctiva (the membrane covering the white of the eye), often associated with itching. It usually occurs in predisposed individuals, typically following exposure to grass pollen or animal fur. Most cases get better within a few hours without the need for drug treatment. However, anti-allergy eye drops may help to control symptoms in the short term and in people with recurrent episodes.