MICHAEL / Eyewear Answers & Calculators

My eye doctor wrote a plus (+) CYL for astigmatism: how do I enter it online?

Direct answer:Transpose a plus-cylinder prescription in three optical steps: add the original SPH and +CYL algebraically for your new SPH, change the CYL sign from plus (+) to minus (-), and rotate the Axis by 90 degrees (add 90 if Axis is 1 to 90, or subtract 90 if Axis is 91 to 180), or email your slip to michael.optical.csr@gmail.com for free verification.

Use the live minus-cyl & axis rule checker below ↓ Shop $16.90 Everyday Frames ($0 CYL Fee) →
Interactive Rx Rule Checker

Verify Your Prescription (SPH, CYL, Mandatory Axis, ADD & PD)

Enter your Right Eye (OD) and Left Eye (OS) numbers below to verify compatibility with MICHAEL Optical’s production boundaries and decode your prescription in plain English.

SPHCYL (US$0)Axis (1–180°)ADD OD (Right) OS (Left) Same ADD

Three-Step Optical Transposition (+CYL to -CYL)

Medical ophthalmologists record astigmatism with a positive cylinder (+CYL), while optometrists and surfacing labs grind the exact same toric lens using negative cylinder (-CYL). Both formats produce identical optical power on your eye once all three columns (SPH, CYL and Axis) are transposed together:

  1. New SPH = Original SPH + Original CYL (keep +/- signs): For example, -2.00 + (+1.25) = -0.75, while +1.50 + (+0.75) = +2.25. If original SPH says Plano or 0.00, then 0.00 + (+1.00) = +1.00.
  2. New CYL = Same number with a minus (-) sign: Change +1.25 to -1.25. Never change the sign of CYL without also updating SPH and Axis.
  3. New Axis = Rotate by 90° inside 1° to 180°: Add 90 when your written Axis is 90 or lower (015 becomes 105; 090 becomes 180). Subtract 90 when your written Axis is 91 to 180 (180 becomes 090; 135 becomes 045). Leave ADD and PD unchanged.
Worked ophthalmologist (+CYL) to MICHAEL Optical (-CYL) transposition examples
Written +CYL Rx (Ophthalmologist)Step 1: New SPHStep 2: New CYLStep 3: New AxisEnter Online (-CYL Equivalent)
-2.00 +1.25 × 015-2.00 + 1.25 = -0.75-1.2515 + 90 = 105°-0.75 -1.25 × 105
-4.50 +2.00 × 180-4.50 + 2.00 = -2.50-2.00180 - 90 = 90°-2.50 -2.00 × 090
Plano +1.50 × 0900.00 + 1.50 = +1.50-1.5090 + 90 = 180°+1.50 -1.50 × 180
+1.25 +0.75 × 128+1.25 + 0.75 = +2.00-0.75128 - 90 = 38°+2.00 -0.75 × 038

Two Mistakes to Avoid at Checkout

  • Never flip the CYL sign alone: Entering -2.00 -1.25 × 015 when your doctor wrote -2.00 +1.25 × 015 puts the cylinder 90 degrees off-axis and shifts spherical power by 1.25 D, causing immediate double-edged blur.
  • Leave ADD and PD untouched: Multifocal near boost (ADD +0.50 to +3.50) and Pupillary Distance (PD) stay identical before and after cylinder transposition. Every transposed cylinder down to -6.00 D (-8.00 D on 1.74 Advanced Progressives) carries US$0 astigmatism surcharge.

Follow-Up Questions Buyers Ask

Why is Axis 000 invalid on online eyeglass forms?

In ophthalmic optics, 0 degrees and 180 degrees represent the same horizontal meridian, and prescriptions always record horizontal axis as 180. If your doctor wrote x180 on a plus-cylinder Rx, subtracting 90 gives Axis 90; if they wrote x90, adding 90 gives Axis 180.

Does transposing from +CYL to -CYL change my lens thickness or price?

No. Plus-cylinder and minus-cylinder notations describe the exact same physical curve on the finished lens. At MICHAEL Optical, cylinder corrections down to -6.00 D add US$0 extra fee.

Can MICHAEL support double-check my transposed numbers before I pay?

Yes. Email a clear photo of your signed paper prescription to michael.optical.csr@gmail.com and our team will reply with the exact OD and OS minus-cylinder values to select in the configurator.

Clinical & Regulatory References