Measuring Your Focusers Progressive or Bifocal Lens Segment Height
Segment Height, also known as Seg Height or SH is only absolutely necessary for progressive lenses, although it is helpful for all types of multifocal lens styles.
It is the vertical measurement in millimeters from the bottom of the lens in your frames, to the beginning of the progressive addition on a progressive lens, or the top line of a lined bifocal. The determined Segment Height is specific to each frame and wearer because it depends on how the frame sits on the face and where the pupils are in relation to the frame's lenses.
Measure Segment Height Yourself (actually with a Friend):
An optician, optometrist, ophthalmologist, etc. should take this measurement if possible. But if that is a problem, here is how to do it yourself:
- Put on the frame that you will be using.
- While looking straight ahead, as you would normally look into the distance (through the person measuring), have someone else look straight at you and dot the lens directly in front of the center of your pupil, with a Sharpie. If you measure it yourself, it will be incorrect. You can remove the Sharpie mark with rubbing alcohol. Take the measurement a few times to get an accurate and consistent measurement if you feel you need to.
- Send the frame back to us, and we will measure the distance from the bottom of the lens (not the frame), to the center of the dot, in millimeters. This will be your segment height and basic pupil distance.