I often get asked what I think of Similasan eye drops. They're a whole line of common, OTC home remedies for "tired eyes", "itchy eyes", "styes", "computer eye relief", etc. They're safe and FDA approved. They will not harm you. They're not, however, very effective IMO. 1st of all the name "Similasan" has to do with the herbal concept of "similitude", which says basically that plants that have parts that look like a human eye should help "heal" a human eye if used on a human eye. So herbs like "eyebright" and "marigold", etc have stems/stalks/bulbs that resemble the shape of a human eye, so therefore we should use them on a human eye. Ok well that does not sound very scientific to me. Another common theory subscribed to and appearing in many herbal medicines is that of "infinitesimal concentration", which says that the LESS concentrated a substance is, the MORE "potent" it becomes. Well ok I am not a big believer in that, either. So what do I think of Similasan? I don't think it works. I think the carrier (buffered saline/water) is probably somewhat soothing and the preservative (silver sulphate) is bacteriostatic/virostatic (prevents active growth of bacteria/virus). Other than that, I think most people would be better off using a good artifical tear like "Systane Ultra" if their eyes are irritated, and if they are itchy they should try an OTC ocular antihistamine like "Alaway" brand eye drops. Similasan won't hurt you, but it probably won't help you much, either.