What are Trifocals?
Trifocals work like the progressive eyeglass lenses, but there are lines dividing the distance, intermediate, and reading areas. There is a 7×28 trifocal which has a 28 millimeter wide segment like the Ft 28 bifocal, and the 7×35 which is 7 millimeters wider, same shape. There is also the executive trifocal that has the lines dividing the vision segments that go across the width of the entire lens.
