I bought a pair of Pure Titanium eyeglass last week,it feels weel at the beginning,while in the hot summer ,when I perspired ,the eyeglass often slide from my face.

I have never heard of that, Pure titanium frames are easy to slide?
Titanium frames are more durable than ordinary steel eyeglasses frames, and they are comfortable to wear, I think that's because of the sweat on your nose at this hot summer!