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understanding your prescription

understanding glasses prescriptionunderstanding glasses prescription

how to read a glasses prescription

To order new glasses, you need a current glasses prescription. This prescription contains several details that together ensure the right correction for your eyes. It might look a bit complicated at first, but don’t worry! It’s easier than it seems. We’ll guide you step by step through what all the numbers and letters mean.

the information on your prescription

A glasses prescription can look slightly different depending on your optician. Some list the details on your invoice, others on a receipt or a glasses card. However it’s presented, the information is almost always the same.

the most important correction values

eye strength (SFER, S, SF of SPH)

Your eye strength is indicated by S or SF, sometimes written as SPH or SFER. After these letters, you’ll see either a plus or minus sign, this shows whether you need a correction for farsightedness or nearsightedness. If there’s no sign shown, it means it’s a plus value.

cylinder strength (C, CIL of CYL)

Not everyone has a cylinder strength. If you do, you’ll recognize it by the abridgment C, CIL, or CYL. A cylinder strength corrects an oval-shaped eye and usually has a negative value. At Wink & See, we don’t charge any extra costs for cylinder correction.

AS (AS, A, AX, AXI, AXS of AXIS)

A cylinder strength always comes with an axis. This indicates the direction in which the cylinder correction needs to be applied. The value lies between 0 and 180. On your glasses prescription, it can be written in several different ways: AS, A, AX, AXI, AXS, or AXIS.

addition (ADD)

This is a reading addition, and you’ll only find this value on a prescription for reading glasses or multifocal glasses. The value is usually between +0.50 and +6.00, and it’s often the same for both eyes. Sometimes it differs per eye: in that case, it’s indicated as OD (right eye) and OS (left eye).

example progressive glasses prescription

Does your prescription look a bit different? Take a look at the various examples of glasses prescriptions here. 

pupillary distance

The pupillary distance, or PD, indicates the distance between the centers of your pupils, measured in millimeters. Sometimes, a separate distance is measured for each eye: you can enter your PD as either one value or two values, depending on what’s on your prescription. If your PD isn’t listed on your prescription, don’t worry! You can easily measure it yourself using our online guide.

measure pupil distancemeasure pupil distance

prism

A prism correction is prescribed for people who experience double vision. On your prescription, this is indicated as prism or prisma, along with a direction noted as ‘base’. At Wink & See, glasses with a prism correction are not available through the website by default, but they can be arranged on request. For an additional fee of €20, we’ll be happy to take care of it for you. Simply contact our customer service to get started.

Some values on your prescription don’t need to be entered when placing your order:

  • Visual acuity and eye pressure: these relate to the health of your eyes, not to your prescription strength
  • Height (the distance between your pupil and the bottom edge of the lens): this varies per frame, we determine this automatically using a smart algorithm

submitting your glasses prescription

Can you read your prescription now? Then you’re all set to order your new glasses! During the ordering process, you can easily enter your prescription values so that we can craft your lenses with perfect precision. Together, we’ll make sure your glasses fit your eyes perfectly.

frequently asked questions
Understanding your glasses prescription helps you choose the right lenses and prevents mistakes when ordering online. Knowing what each value means ensures you select the correct lens type and strength for your needs. For step-by-step help, visit order glasses online or explore our different lenses to see which options suit you best.
Check that your name, date, and the values for each eye are correctly written. Compare it with your previous prescription or your current glasses. If you’re unsure about any numbers or abbreviations, contact us via contact or see order glasses online for more guidance before ordering new lenses.
OD (oculus dexter) refers to your right eye and OS (oculus sinister) to your left eye. Sometimes OU (oculus uterque) is used, meaning both eyes. These abbreviations ensure the right correction is applied to the correct side. For more information, visit glasses prescriptions for a full explanation of how your prescription is read.
The add value (ADD) is the extra strength needed for near vision and is typically used for multifocal or reading glasses. It’s added to your distance correction to create a smooth transition between far and near vision. Learn more about how this works in progressive lenses.
The pupillary distance, or PD, measures the space between the centres of your pupils. It’s essential for aligning the lenses correctly in your frames. If your PD isn’t listed on your prescription, you can easily measure it yourself with our guide pupillary distance. This ensures your glasses fit perfectly for natural vision.
A glasses prescription is usually valid for one to two years, depending on your eyesight and your optician’s recommendation. If your vision changes or you notice more strain, it’s time for a new eye test. Afterwards, you can order fresh lenses or choose a complete frame at glasses.
If your prescription hasn’t changed, you can often reuse the same strength for a new pair. Make sure your current glasses are still in good condition and fit well. When ordering a new pair, you might consider transition lenses or blue light lenses for added protection and comfort.
That depends on your vision needs. If you have one prescription per eye, choose single vision lenses. For both distance and near vision, progressive lenses are ideal. Work long hours at a screen? Try blue light lenses to reduce eye strain.
Don’t worry — optical terms can be confusing. You can read clear explanations on glasses prescriptions or contact us via contact for help. You can also check order glasses online for guidance on entering your details correctly.
When ordering online, enter your prescription values exactly as shown on your form. Double-check all numbers and symbols before completing your order. If you’re unsure about any step, see order glasses online for step-by-step instructions. This ensures your lenses match your vision perfectly.