Hinges on a spectacle frame can tell you a lot about the quality of the frame itself. I know? Would you believe it? It can help you distinguish between what I would call a mass market/ mass produced frame where they (the manufacturers) want as many people to buy them versus a better quality hand made frame.
A mass market frame (like most of the recognisable designer brands you'll find on the high street) will have a spring hinge. This is for one main reason (and more cynical reasons) which is the spring means that the frame doesn't have to fit you perfectly for you to buy it. The spring gives it a bit of flex so it the frame is too small it can be worn as it doesn't feel too tight. This means they can fit more faces and sell more frames. The more cynical reasons are that the spring hinge is cheaper and the nature of the spring within the hinge means that at some point it's likely to snap. It's the weakest point on the frame and the part that always tends to break with a little rough usage. If you are lucky you'll be able to get a replacement side but more likely you'll need to buy a new frame to replace it - and hence they get to sell more frames.
The better quality hand made or hand finished frames will normally have some seriously sturdy hinges. These aren't going to snap, you've got to put some serious pressure onto a side to get it to break.
I recently managed to break a frame playing football with my children, I made a fantastic defensive header which means the ball basically hit the side of my head/glasses and the glasses side popped off. The hinge was fine, it was a solder point that went. The hinge was completely intact and not twisted at all which meant that it could be repaired by soldering the side back on. It really highlighted the quality of the frame and if you are wondering what brand - it was a pair of my Tree spectacles.
The better quality hinges are obviously more expensive and are usually made by a more independent frame manufacturer who is more intent on quality than mass market appeal. If the frame doesn't fit, then it doesn't fit. They probably produce something in their range that will.
I hope this helps you to get a better understanding a feel for the quality of different glasses brands!
