Vision Science and Optometry

Conjunctivitis is an inflammation (swelling and irritation) of the conjunctiva, the thin layer of tissue covering the eyeball and the inner surfaces of the eyelids. This causes the blood vessels of the eye to swell, making the eye look bloodshot red and feel gritty and sometimes painful. Conjunctivitis can be caused by an irritant, such as chlorine or dust, an allergy (for example, to pollen), or an infection by microbes (bacteria, viruses, Chlamydia etc.).