Short corridor vs Long corridor

[Mrmessi]

When it comes to progressives, what is the major difference between the two.

For example the depth of the frame is 30 and the height is 21. What difference would a short corridor make vs a long corridor.

What is the patient gaining or compromising comparing the corridors.

[fagin]

Short corridor with low adds reduce vertical head movement, which some find useful if they're sitting at a workstation. Higher adds can cause problems with short corridors, as progression changes too quick, and will add extra unwanted oblique astigmatism. Personally I like to wear a longer corridor if the frame is suitable (hyperope with 225 Add).

[Yeap]

beside those more technical issue such as distortion, visual field zone. always take into consideration the vertex distance in order to fit your patient with a comfortable pair of glasses.