Anyone used it or know of someone that has?? Did it work?? What are your thought??

I saw my OB yesterday and was discussing my birth options with her as I sustained a 3rd deg tear with DD and still get pain from it all. I definately would prefer a natural borth but am terrified of tearing like that again. I asked her if there was anything I could do to prepare the area to reduce my chances of tearing and she suggested the Epi-no to me. Apparently the studies in the US have shown good results from the use of it, but I don't really know how you could come to the conclusion that it helps when some people tear and others don't, but I'm not scientist!!!

TIA any info would be much appreciated!