1.74 Index Lens for Semi-rimless Frame
Can 1.74 index be used on semi-rimless frame?
I was told by the local provider that 1.74 cannot be used for semi-rimless frame, has to go to 1.67. is it true or not?A:
Well, the answer is more complicated than this...
It depends on the diopters of the lens and how big is the frame.
There is a minimum thickness that the lens must have for mounting in the semi-rimless frame.
The 1.74 index lenses are indeed thinner. If you add this to (+) diopters (they are thinner at the edges), you got an extra thin lens that you cannot mount in the semi-rimless frame.
In this case, I recommend you a smaller frame, because the lens is thicker at the center.
If your diopters are (-), then the lens is thinner at the center, so a 1.74 lens is even thinner, but get thicker at the edge, so if this is your situation, I recommend a bigger frame, this way maybe it will meet the minimum thickness.
All this if you insist having the 1.74. If this is not possible, then I think the 1.67 is not a bad option.
Hope this helps,