The conjunctiva is the thin layer of tissue that covers the outer surface of the eye. Conjunctivitis can affect one or both eyes. It comes in different forms:
- Infective conjunctivitis – bacterial or viral infections, such as the common cold, can lead to this highly-contagious form of the disease. Infected contact lenses or contaminated eye make-up may also be responsible.
- Allergic conjunctivitis – allergic reactions to pollen, animal fur or dust mites can inflame the conjunctiva.
- Irritant conjunctivitis – substances such as chlorinated water, shampoo or air pollution can irritate the eye. A loose eyelash can also lead to this form of conjunctivitis.