Standard Freeform Technology

Written by Optician Club on . Posted in Conventional Progressive Lenses, Freeform Rx Lenses, Progressive Lenses

The first question comes to Standard Freeform technology is the necessity of existing, when we have a better choice for Personalized Freeform Technology. In case of a picky customer insist to have an exact power like old prescription sheet, the Standard Freeform technology will be the option to such demand.

  • Like conventional lenses but produced with digital surfacing equipment
  • Not personalized
  • The parameters face/frame are not necessary
  • Includes variable inset
  • Easy to be checked with a focimeter

Prescribed power = Measured power

Lens calculated with Standard Freeform technology: Perceived Power

Standard Freeform Technology

The pantoscopic and wrapping angles induce a notable difference in the perceived power and unwanted astigmatism is also appearing due to oblique aberrations.

For example

Prescribed Power: Far: Sph 0,00; Near: Sph 2,00

Measured power: Far: Sph 0,00;Near: Sph 2,00

Perceived power:Far: Sph -0,04 (Cyl -0,02 with Axis 80º)

                         Near: Sph +2,23 (Cyl -0,27 with 172º)

The situation will get even worse when prescription goes higher

Prescribed power: Far: -6,00; ADD 2,50 with panto=12; wrap=10

Measured power: Far: -6,00; Near: -3,50

Perceived power: Far:  -6,32 (Cyl: -0,48 with Axis 136º);
                          Near:  -3,42 (Cyl: -0,25 with Axis 147º)

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