How to read your prescription
Your prescription may look like a code, but it is simple once you know the five key numbers. Here is everything you need to order glasses online with confidence.
| Abbreviation | Meaning | What it does |
|---|---|---|
| SPH | Sphere | The main power of your lens. A minus (−) value means you are short-sighted; a plus (+) value means long-sighted. It is written in steps of 0.25 dioptres, e.g. −2.00. |
| CYL | Cylinder | The amount of astigmatism correction. If blank or written as SPH/DS, you have no cylinder and we simply leave it out. |
| AXIS | Axis | A number from 1 to 180 that tells us the orientation of your astigmatism correction. It only matters when a cylinder is present. |
| ADD | Reading ADD | The extra power needed for near vision, found on varifocal and bifocal prescriptions. Usually the same for both eyes, e.g. +2.00. |
| PD | Pupillary distance | The distance in millimetres between your pupils. Your optician usually prints it on the prescription; if not, we can advise how to measure it at home. |
A worked example
| Eye | SPH | CYL | AXIS | ADD | PD |
|---|---|---|---|---|---|
| Right (OD) | −2.50 | −0.75 | 180 | +2.00 | 31 / 30 |
| Left (OS) | −2.25 | −0.50 | 5 | +2.00 |
This prescription is a short-sighted (myopic) patient with mild astigmatism in both eyes and a reading ADD, so they would need varifocal or bifocal lenses. The two PD figures are the right and left eye distances (monocular PD); you can also give us one combined figure such as 61.
Lost your prescription?
Ask your optician for a copy — by law they must provide it free of charge. If your prescription is more than two years old, we recommend an eye test first. Ready to order? Open the lens studio →