Lemon juice with added salt is the surest way to beat conjunctivitis.
Often conjunctivitis flares up in humid weather and when you move outdoors, your eyes start getting sticky which is indication of infection trying to latch in. start rinsing eyes with a glassful of water with some lemon juice added. add more if infection is more. if eyes have started to pain, add salt to the water. you will find immediate relief. repeat it every few hours. absolutely no harm to the eyes. the infection is completely cured in a day or two.
I have been successful in keeping myself free from conjuntivitis for several years now, just by following the above method. it also makes sense to wash eyes, once in a while with lemon solution to keep them clean, even with no conjunctivitis.