Conjunctivitis is an inflammation of a mucous membrane and therefore in most types there is a red eye, thickening of the conjunctival tissue and some discharge of mucous or mucous and inflammatory cells. The causes of Conjunctivitis include; bacterial infection, viral infection and allergic reactions. Typical bacterial conjunctivitis, is caused by the common staphylococcus and diplococcus pneumoniae to the less common organisms of the haemophilus group. Infection is generally in both eyes with the patient experiencing discomfort in the form of a "smarting" and grittiness, moderate photophobia, but minimal pain. Discharge from the infection causes the well known symptoms of eyelids stuck together on wakening or having a "crusty" appearance. Bacterial conductivities responds well to antibiotic treatment. Viral infections, sometimes caused by adenoviruses which are often involved in upper respiratory tract infections, cause inflammation of the membrane on the back of the eyelid. Allergic conjunctivitis results from hypersensitivity to exogenous antigens. There are many forms, with some examples being, profuse watering due to hay fever, chronic inflammation as a result of a reaction to locally applied drugs. The treatment is to remove the antigen and use of vasoconstrictors.