I doubt you will. How old are you and how has your eyesight been falling throughout your life? (at what pace)
When I was 14, I used to be terrified of this. I mentioned this to my doctor who's treated me my whole life and he said that I'll almost definitely even out at -7,5 or so by the time I'm 19. (He turned out to be right, but it really was frightening for a while, because I went from -1,5 to -5,5 in about a year.)
Seriously though, tell your doc this. Hopefully they can help.