Diving lenses measurements

To make corrective diving lenses for a diving mask there are some considerations to be aware of. Depending on the type of lens needed the following is considered mandatory information to be provided:

  • corrective power far
  • corrective power near (reading/bifocal)
  • pupil distance
  • pupil height
  • segment height

Especially the segment height can be cause for confusion. Proteye uses the so called boxing system where the height of the lower (reading) segment (H) is determined by measuring:

  • from the deepest/lowest point of the window in the mask (seen from the outside) and above any visible silicone parts on the inside. In other words the lowest 'clean glass' point.
  • to the highest point of the desired reading part / segment transition (bifocal).

reading height


Reading lenses are always curved on top which means that bifocal lenses will have a curved transition line between upper and lower segments as well. Since this line will be visible it is important to make sure it is not right in front of the pupil.

It is recommended to mark the height of the lens with a permanent marker, emulating the head position as it would be under water since this usually differs from a upright standing position. This way it is easy for the customer to see if it blocks his vision or not.

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