Keep my hands and face clean. How did I up with conjunctivitis?

It is contagious. Tear ducts communicate with the nasal passages so every cough, nose blow etc sends one person's eye secretions all over and the germs that cause pink eye are really contagious. Good hand washing and asepsis are important ways to limit spread of one person with pink eye to another, but nothing is fool proof. Plus we touch out eyes constantly without realizing it.