I wear glasses too and have had a little of the same problem at times. Most of the time I can fix it just by adjusting where the mask falls on my nose. I've seen a face mask just for people with eyeglasses in the Cabelas catalog but I have no idea how well it works, butit mightbe another idea for you to try.
heres a link
http://www.cabelas.com/cabelas/en/templates/links/link.jsp?id=0024822942320a&type=product&cm Cat=search&returnPage=search-results1.jsp&QueryText=face+mask&N=4887&am p;Ntk=Products&Ntx=mode+matchall&Nty=1& ;Ntt=face+mask&noImage=0