Although my old glasses are completely scratched, when I look through them I cannot see any of them... why ?

The scratches are so close to your eye you probably can't focus on them. It is sort of how a CD will still play if it has scratches (within reason) because the laser doesn't focus on the surface of the disk but below the surface, where the reflective film is. If you have ever used a microscope, you probably have been able to see layers of cells or whatever below other stuff (if it isn't too opaque) by adjusting the focus. In all these cases, the scratches or other stuff in front, don't really show up much if at all, but there is a slight blurring effect when they are there in any apreciable number.

Anyway, if you got some new glasses in the same prescription you would probably be able to see slightly better just because this slight blurring efffect is not there.

Because of their proximity, just like people around Vincent Van Gogh thought of him as a loser and a failure, he was too close to them, only the distance of time was able to reveal to them how unfair and short sighted they were. Familiarity breeds contempt, same with your old glasses. I say, keep em', theyll remind you that there may be a Vincent near you, and youll pay more attention.

probably bc you just got used to them and they are so closee to your eye it is hard to see. my glasses are scratched to and i cant see the scratched when they are on either.