@fBoyle-- Like the article of this article said, this symbol like many Egyptian symbols can have slightly different meanings depending on the context in which it is used and the other symbols accompanying it. As far as I know, the Eye of Horus is mostly about health of the body, recovery from illness and also prosperity. It can also be used to refer to eye health specifically. It was sometimes worn by people as a talisman to protect against "evil eye."
The concept of "evil eye" still exists in many cultures today. And in the Middle East, you will see a lot of necklaces and jewelry in the shape of a blue eye. People may wear them believing that they will ward off "evil eyes." The meaning of "Evil eye" is jealousy and hatred of others that can cause one to become ill.
I think that today's evil eye talismans are actually an extension of the Eye of Horus but many people do not know. The strange part is that many of the cultures who believe and use this are Muslim cultures where the belief of objects granting protection generally isn't accepted. We can say that it's a cultural tradition that has stuck on.