Designed by a Kiwi optometrist. He checks eyes and puts glasses frames on faces all day, every day. That’s what he does.
He knows why glasses frames work and why they don’t. He knows which frames are rubbish and which ones aren’t.
He knows structurally where the frames can be weak. He knows this because he does this every day.
He does not design handbags, or dresses… not even suit pants…
Because he can’t. Because he does not do that every day. Eyewear is his thing.