LensWright: Optician Calc

The optician's math, done right. Vertex per meridian, Prentice, transposition, thickness. $4.99 once — not a subscription.

LensWright is the calculator opticians, lab techs and ABO students actually need — and it costs $4.99 once, not $4.99 a month.

Enter the Rx once. Every calculator prefills from it.

FREE, UNLIMITED • Sphero-cylinder transposition (plus-cyl ↔ minus-cyl) • Spherical equivalent • Vertex compensation — applied PER MERIDIAN and re-formed, not just on the sphere

FULL UNLOCK ($4.99, one time) • Prentice's rule and induced prism • Vertical imbalance with a slab-off indicator • Oblique meridian power • Sagitta, centre and edge thickness • Minimum blank size • Compound prism (resultant magnitude and direction) • Tilt and wrap (Martin's formula) • Saved Rx history • Lab-order PDF export

WHY VERTEX PER MERIDIAN MATTERS Compensating only the sphere is the classic error. A −8.00 −1.50 × 175 does not keep a −1.50 cylinder at the corneal plane — it comes back near −1.23. LensWright compensates each meridian and re-forms the prescription, so what you order is what you meant.

EVERY RESULT SHOWS ITS FORMULA You can check the work. That is the point.

100% ON DEVICE No account. No network. No tracking. Any prescription you enter stays on your iPhone.

For professional reference only. Always verify before ordering or dispensing.