An ophthalmologist's slip is written in shorthand that was never meant for patients. This guide reads one the way an optician does, so you can check it before you order glasses. For the basics of each term, our prescription basics guide goes deeper. Here we focus on what you are actually looking at on the slip, and on the part people find hardest: cylinder and axis.
Don't want to decode it yourself? Send a photo of your slip on WhatsApp. One of our opticians will read it back to you and confirm it before any lens is cut. You can also upload it from any frame page with Order via WhatsApp / Upload Rx.
Step 1: find the two rows, OD and OS
OD is your right eye and OS is your left. Some slips use R and L. Always follow the label rather than the position on the page, because a swapped row means swapped lenses.
Step 2: read each column left to right
| Column | What it is | What it looks like |
|---|---|---|
| Sphere (SPH) | The main lens power. Minus (−) is for distance vision problems, plus (+) is for near-focus problems. | −2.50, +1.75 |
| Cylinder (CYL) | Extra power that corrects astigmatism, where the eye is shaped less evenly in one direction. | −0.75, −1.50 |
| Axis | The direction, in degrees from 0 to 180, along which the cylinder sits. Only written when there is a CYL. | 90, 180, 15 |
| ADD | Extra reading power, used for bifocals, progressives and reading glasses. Blank for single-vision distance glasses. | +1.50, +2.25 |
| PD | Pupillary distance in millimetres, the distance between your pupils. Sometimes written as two numbers, one per eye. | 63, or 31/32 |
You may also see DV (distance vision) and NV (near vision) rows, PL or plano meaning zero, and VA or 6/6, which records how well you read the eye chart. VA is a test result, not a lens power, so you don't need to enter it when ordering.
Why cylinder and axis must go together
A spherical lens has the same power in every direction. A cylindrical lens does not. It has power in one direction and none at right angles to it, like a slice of a drinking glass. That is why a CYL value is meaningless without its axis, which tells the lab which way to turn the lens.
Alignment matters because the lens has to sit in the frame at exactly that angle. If the axis is off by even a few degrees, vision can look blurred or tilted, and the error grows as the cylinder gets stronger. Three details follow from this:
- Always enter CYL and Axis as a pair. One without the other can't be ground.
- Axis 90 and 180 are not interchangeable. They are different directions.
- The frame and the lens cutting both have to keep that angle, which is why astigmatic lenses are marked and checked on a lensometer before they leave the lab.
A worked example
Suppose the right-eye row reads −2.00 / −0.75 × 180. In plain words: the right eye has −2.00 of main power, plus −0.75 of cylinder aligned along 180 degrees. The left row is read the same way. We don't interpret what these numbers mean for your eyes. That belongs to your doctor. We only make sure the lens is made exactly as written.
Common slip mistakes to avoid
- Dropping the + or − sign. They are not optional.
- Copying the OS row into the OD box.
- Entering the VA (like 6/6) as a power.
- Using an old slip. Prescriptions can change, so if yours is more than a year or two old, ask your doctor whether it is still current.
Visit or message us
EYVRO is the online brand of Deepak Opticals, Aligarh, opposite Gandhi Eye Hospital on Ramghat Road. Open 10:00 AM – 8:00 PM, Monday to Saturday. Get directions, message us on WhatsApp, or see our store page.
