bungeejumper wrote:mtk62 wrote:I have had 3 sets of frames break recently - 2 of those were safety glasses (which I only used for cycling).
These were all expensive frames and weren't flimsy.
Hang on, you're saying that the lens prescription can affect how long the frames will last? I could imagine that a very thick lens could put stress on a metal frame, which is why my optician sometimes advises against such things. (I have a prism.) But otherwise I'm not sure how the problem could arise. Any details? Thanks.
BJ
Not many people visit an optician with the object of buying lenses, they are primarily looking for a spectacle frame they like and the lens type is a secondary consideration. My advice would be to choose the lens design first and then see which frames are suitable to house your chosen lenses not the other way round. Not all frame styles suit all lenses as your prescription may affect your lens index for cosmetic purposes. The main lens indices (thickness basically) are 1.50, 1.53, 1.56, 1.60, 1.67, 1.74, starting at 1.50 being the thickest.
Safety glasses would typically be 1.60 which is polycarbonate and has great impact resistance, an alternative is 1.50 CR-39 which are arguably just as good but offer much greater scratch resistance.