Saliva is the water-like substance produced by salivary glands in mouth. About 99.5% of saliva is water, while the rest 0.5% includes enzyme, electrolytes, mucus, glycoproteins and some antibacterial compounds. From its components we could know that saliva could be safely applied to eyes. With water and mucus, saliva is believed to lubricate eyes just as tear film. Some doctors recommend putting saliva in eyes to relieve eye dryness. Saliva is believed to be disinfectant too. This is why, most people believed, animals usually lick their wounds to expedite the recovery. Saliva could kill some bacteria in mouth and throat. So if you apply saliva in eyes, it might be helpful with bacteria killing and infections controlling. However, all these benefits are based on normal production of saliva. If there is something wrong with your salivary glands or mouth or throat, you'd better not do so in case any bacteria or virus in saliva will cause conjunctivitis.