The terms progression corridor and corridor length are commonly used for progressive lenses.
They generally describe the vertical path over which power changes from distance toward near, although exact definitions and labels vary among manufacturers.
01 · CORRIDOR
The corridor is the main vertical path of power change
As gaze moves downward from the distance area, additional plus power increases toward the near area. The principal region over which this occurs is called the progression corridor.
Corridor length is not simply another name for the frame height. It generally describes the main path over which power progresses toward the full near addition, but manufacturers may define and label that distance differently. Numbers should therefore be compared only after checking what each manufacturer is measuring.
02 · SHORT CORRIDOR
The same add must change over a shorter distance
A short corridor can fit smaller vertical frame dimensions. However, the same addition changes more rapidly, which alters the trade-off between usable width, gradients and peripheral aberration.
A short corridor can help place the near zone into a shallower frame, but it also means the same addition must develop over less vertical distance. The resulting power gradient and peripheral aberration distribution can change, so shorter does not automatically mean easier or better.
03 · LONGER CORRIDOR
A longer corridor spreads the change over more vertical space
The transition can be distributed over a longer distance and the intermediate zone can occupy different vertical space, but sufficient frame depth and fitting height are required.
A longer corridor can spread the power change over more vertical space and may feel more gradual, but the wearer may need to look farther down to reach the full near zone. Its benefit depends on working distance, gaze habits and whether the frame provides enough usable depth.
04 · FRAME HEIGHT
Corridor choice is tied to available frame depth
If the lower lens edge is too close, the intended near zone may be truncated. Small frames require checking the product’s minimum fitting height and available corridor options.
If there is not enough space below the fitting point, part of the intended near region can be lost during edging. Minimum fitting height is therefore a practical condition for placing a specific design in a frame, not just a marketing recommendation. It must be considered from the final wearing position.
05 · NOT ONE NUMBER
Corridor length alone is not a performance grade
Two designs with the same nominal corridor can distribute power and aberration differently. Consider add, design, frame and fitting height together.
Corridor length is not a quality ranking. Two lenses with the same nominal length can distribute distance, intermediate, near and unwanted astigmatism differently. The prescription, frame and task priorities matter more than choosing the shortest or longest number by itself.
SOLUTION GUIDE
Solution guide
Confirm that a suitable short-corridor option exists.
Consider actual intermediate-zone performance, not corridor length alone.
Do not assume the shortest corridor is automatically best.
GLANOS LENS CHECK
Do not force a lens design into an unsuitable frame
Choose a progressive design that matches available frame depth and fitting height.
CAUTION
A shorter corridor does not mean newer or more premium
The appropriate corridor depends on use and frame conditions.
GLANOS EYEWEAR
There is a reason glasses feel uncomfortable.
progressive corridor · progressive lenses · fitting height · multifocal lenses · frame selection