How to Read Your Glasses Prescription

Your glasses prescription is a set of measurements from your optometrist that tells our laboratory technicians exactly how to make lenses to correct your vision. To most people it looks like a confusing row of numbers, abbreviations and + and − signs.

This guide will help you in understanding glasses prescriptions. So you can read your prescription confidently. Understand what each value means for your vision, and enter the details correctly when ordering glasses online.

Whether your prescription is simple (just a sphere value for each eye) or complex (including cylinder, axis, prism and a reading addition). This guide covers every abbreviation you are likely to see.

If you have a prescription from the NHS, Boots, Vision Express, Specsavers or any other optician in the UK. The terms below will appear in some form on your prescription.

By law in the UK, your optometrist is required to give you a copy of your prescription, without any obligation to buy glasses from them. This is set out by the General Optical Council (GOC). You are entitled to take your prescription to any optical retailer to buy your glasses.

If you did not receive your prescription, or if you have lost it, contact the practice where you had your eye test and ask for a copy. They are required to keep records and should be able to provide one.

What does SPH CYL and AXIS mean? 

Sphere (SPH): The sphere on your prescription represents the lens strength required for clear vision. A minus (-) sign indicates nearsightedness (short-sighted), while a plus (+) sign indicates farsightedness (long-sighted). If the SPH column shows 0.00, Plano, PL or an infinity symbol (∞), it means you have no spherical correction in that eye.

Tip: A quick way to remember: minus = short-sighted (distance blurry); plus = long-sighted (near blurry).

Cylinder (CYL): The cylinder value reflects the lens power needed to correct astigmatism. If this section is blank, it means you do not have astigmatism.

Axis: If you have astigmatism, the axis number indicates the specific angle at which the lens should not have cylinder power, so your astigmatism is corrected properly. This will be a number between 1-180.

Tip: Enter the AXIS exactly as written on your prescription. Do not round it. Entering 12 when the prescription states 125 would result in incorrectly made lenses.

Addition (ADD): ADD (sometimes written as Near Add, NV Add or Reading Addition) is the extra magnification power added to the distance prescription to help with close-up tasks such as reading, computer use or close-up work.

Pupillary Distance (PD): PD is the distance in millimetres between the centres of your pupils. If your prescription does not include a PD, you can measure it at home using our step-by-step PD guide. It takes less than two minutes with a ruler and a mirror.

A typical UK glasses prescription is laid out as a table with two rows, one for each eye, and several columns. The right eye is always listed first and is labelled R, RE or OD (oculus dexter, Latin for right eye). The left eye is listed second and is labelled L, LE or OS (oculus sinister, Latin for left eye).

While all UK opticians follow the same clinical standards, the layout of prescription can vary. NHS prescriptions, Boots opticians, Vision Express, Specsavers and independent opticians may each present the same information in a slightly different format. Below are some examples of common optical prescriptions from several well-known high street opticians. For each example we have shown how the details would look when entered on our website.

Here are several examples of more unusual values you may find and what to do if they apply to you.

Prism and Base: If you have a prism value listed for one or both of your eyes then a number (Power) and direction (Base: Up, Down, In or Out) will be provided.

We can provide lenses with a prism correction between the Powers of 0.25-3.00.  There is an additional charge for lenses to be made with a prism.

DS (Dioptre Sphere): The prescription below has DS written under the CYL column.  DS (Dioptre Sphere) means there is no astigmatism or no value present, you can leave the field blank. There is also +2.50 written once in the Add field.  This is the addition value for both eyes, although written once this would need to be entered for both eyes.

Plano / PL / ∞ (infinity symbol): means 0.00, no spherical correction needed in that eye. You may still have an astigmatism correction (CYL and AXIS values). You can either select 0 from the drop down or leave the field blank.

BAL (Balance): is sometimes written in one eye's column to indicate that the lens for that eye is a balance lens (non-prescriptive). This is used when one eye has very poor vision and will not benefit from optical correction.

Sometimes you will be provided with Aided VA or BVD values.  These are not needed to make your lenses.

As well as telling us how to make your lenses, your prescription reveals something about how your eyes work:

Short-sightedness (Myopia): A minus (−) SPH value means you are short-sighted. You can see things close to you clearly, but objects at a distance appear blurry. Short-sightedness is the most common refractive error in the UK and typically develops in childhood or teenage years. It usually stabilises in adulthood, though prescriptions can continue to change.

Long-sightedness (Hyperopia): A plus (+) SPH value means you are long-sighted. Younger people can often compensate for long-sightedness using the focusing muscles of the eye. Meaning they may not notice blurry vision at typical distances until they are older. As the eye's ability to compensate reduces with age, symptoms become more apparent, particularly for near tasks.

Astigmatism: A CYL value on your prescription means you have astigmatism. A common condition where the cornea (the clear front surface of the eye) is slightly oval rather than perfectly spherical.

This causes light to focus at multiple points rather than one. This can result in blurred or distorted vision, ghosting around letters or objects, and difficulty seeing fine detail. Astigmatism can occur alongside short-sightedness, long-sightedness, or on its own.

Presbyopia and Reading Addition: From around the age of 40, the natural lens inside the eye gradually loses its ability to change shape and focus at different distances. This is called presbyopia and it is a normal part of ageing.

If you have an ADD value on your prescription, it means you have presbyopia and require additional correction for reading or close-up tasks.

Practical options are varifocal lenses, bifocal lenses, or a separate pair of glasses for reading glasses.

When you reach the add glasses prescription step during checkout at Direct Sight, you have three options:

1. Upload your prescription, photograph or scan your prescription slip and upload it. Our team will check every value before making your lenses. This is the method we recommend, as it eliminates the risk of manual entry errors.
2. Enter the values manually, type each value from your prescription into the corresponding field. Take care with the + and − signs, decimal points and the AXIS value. If you are unsure about any value, upload rather than enter manually.
3. Send it later, complete your order and email your prescription to help@directsight.co.uk before we begin making your lenses.

Providing the correct prescription details is crucial when ordering glasses from Direct Sight, as it ensures you receive lenses that perfectly match your vision needs. Accurate prescription information guarantees that your glasses provide optimal clarity and comfort, preventing issues like eye strain, headaches, or blurred vision.

At Direct Sight, we make it easy to provide your prescription details by offering the options of sending your prescription details after you have placed the order or attaching a copy of the prescription to your order.  Our experienced team can then input your prescription, to double-check the details, such as sphere, cylinder, and pupillary distance, to ensure your lenses are tailored to correct your eyesight precisely, allowing you to confidently order glasses online.