Eyeglasses are no longer just a kind of vision correctiong, it`s more a kind of decoration now, so different shape of face should match the right frame.

Round face -----Oblong frame It makes the wearer`s face more ridgy

Downfallen triangular face---small sized frame

Triangular face----wide frame It will make the wearer`s forehead look more wide

Quadrate face---wide frame