This refers to the lens design which includes three fields of vision, without lines, and is sometimes
referred to as a "no-line multi-focal".
In a progressive lens, the shape of the corrected part of the lens is approximately that of a funnel or a
mushroom. The top portion is for distance-vision, narrowing to the lower middle for mid-range, finally to
the bottom portion for the near-vision or reading. The reading area is expected to be smaller than the
distance area. People sometimes prefer a single-vision lens for extended reading or up-close work.
The lens height for a progressive lens must be 36mm or greater. We recommend a taller lens for more
comfortable wear, but the minimum lens height is 36 mm. If this frame has a lens height smaller than 36mm, a
different frame must be chosen for progressive lenses.