Make sure you have them in the correct way...if you don't it will cause your vision to blur. If thats good...the only thing I can think of is that you should try adjusting your ancor somehow so you aren't looking through at an angle. I'm trying to think how I shoot...I'm pretty sure I turn my entire head and look straight on.

Having hunted archery both with glasses then contacts, I can without a doubt say that contacts are better. Try to figure them out instead of just going with the glasses. Contacts won't fog up from heavy breathing when a big buck walks infront of you