xkcd

I couldn't tell ya 🤷🏾‍♂️ it's entirely possible that the risk of the lenses splitting was exaggerated to justify their requirement of buying the more expensive lenses with the half frames.

Unrelated, but when I was buying my glasses, I'd fallen in love with these half frames, but disappointedly told the tech I'd have to pick a different pair when she told me about the increased expense. (It wasn't that much more, relatively speaking, but I already couldn't afford the glasses, and had explained earlier that I was trying to do things as cheaply as possible). When she saw how upset I was over not being able to get the frames I really liked over an ultimately negligible amount of money, she gave me the glass lenses for the plastic lense price.