Conjunctivitis is the most common eye disease in the western hemisphere. It's an inflammation of the conjunctiva which makes the sclera appear reddened due to an increase in blood supply.

An eye with conjunctivitis feels itchy and watery and sometimes there can be a sticky discharge, which feels uncomfortable and blurs the vision.

Although conjunctivitis is sometimes referred to as 'pink eye', this only really refers to one type of the disease, bacterial conjunctivitis.