This post will wrap up my recent eyewear posts.
Browsing glasses online you’ll often see specs like this:
Lens/Eye: 46 mm
Bridge: 22 mm
Temple: 143 mm
These three measurements affect how your glasses look and stabilize on your face.
What do these measurements indicate?
The “Eye/lens” measurement indicates the length of one lens from one end to the other. The frame is not included. Illustration below:
Opticians tend to suggest your eyes be centered on the lens.
One reason is aesthetic, so you don’t look cross-eyed or like you’re wearing oversized glasses. Some people like the latter look, which is rather stylized. I don’t believe there’s a particular medical reason for centering your eyes.
Sunglasses have more flexibility since oversized frames are generally popular.
The “bridge” indicates the distance between two frames:
Bridge length can also affect the glasses’ proportions on your face, but less so than lens size.
That’s because differences in bridge lengths are usually incremental.
Lastly, each glasses has a pair of temples that join to the frame, securing the glasses to your head.
Temples can be tricky. They should neatly wrap behind your ears and gently press to the sides of your head.
For example, I had a pair of sunglasses with temples too long. They constantly fell forward because they didn’t securely fit around my head.
Someone helped me shorten the temples and alter the nose pads. They’ve never been more comfortable.
So you have wobbly glasses, see if they can be adjusted by your optician.
Bridges and frames tend to be fixed and inalterable (unless you own a wire frame), but there are other areas that can.