A frame with clear demonstration lenses on a leather fitting mat, a small fitting cross marked on each lens.

Measuring and fitting

Fitting height

Optical glossaryMeasuring and fitting

The vertical distance from your pupil center to the bottom of the lens in your chosen frame. The most common cause of progressive remakes when wrong.

Fitting height sets where the corridor starts. Set right, you look straight ahead through the distance zone; too high and you look through the corridor; too low and reading sits further down than your eyes comfortably go.

Illustrative · the shape of the principle, not measured data

In more depth

Fitting height is measured on your face, in the frame you will wear, from the center of the pupil down to the lowest point of the lens opening. It tells the lab where the progressive's fitting cross goes — the point where distance vision ends and the corridor begins.

Set too high and the wearer looks through the corridor when trying to see far; too low and reading means tipping the head back. Every progressive design needs a minimum height to fit its corridor and reading zone below the pupil, which rules out very shallow frames for some designs.

Related terms

CorridorThe channel of clear vision running down the center of a progressive, connecting the distance and reading zones.Progressive lensA lens whose power changes gradually from distance at the top to reading at the bottom, with no visible line.RemakeA lens made again due to error or non-adaptation. The most common causes: fitting height and frame changes after measurement.Monocular PDYour PD measured separately for each eye, from the nose bridge. More accurate than a single figure, and required for individualized lenses.

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