Contact Lens calculator

Practical toolbox to calculate the contact lens parameters.

Relax Optic Variation

Lag of Accommodation

(measured in 33-40cm)

Lag of near fixation

(with Modified Thorington Cross, measured in 33-40 cm how much Add is needed to get a regular test image)

Pupil size

(measured in room lighting)

NightFlex

NightFlex Relax

We recommend Modified Thorington Cross to measure at near, If you don’t have, you can use the practical Near test APP from Smart Optometry App to measure the Near Lag of fixation with children.

Over-refraction calculation

Contact lens
Over-refraction
Result

Eyeglass power conversion

Spectacles
Contact lens

Corneal curve conversion

Sagittal height calculation

Zone 1

Zone 2

Zone 3

Last zone diameter corresponds to total contact lens diameter (ØTot)

Transposition Cyl+ / Cyl-

Axe present / Axe with stabilisation

(RGP) Power adjustment with BC changes on RGPs

Calculation of numeric eccentricity

Kreading (centre)

Peripherial keratometry @ 30°

Eccentricity