Understanding your spectacle lens prescription
Understanding your spectacle lens prescription

Understanding your spectacle lens prescription

Understanding your prescription can be a little confusing, with so many abbreviations and numbers, it’s easy to forget what it all means. Here's a quick overview to refresh your memory.

Whether it’s your first time being prescribed spectacle lenses to correct your vision, or you’ve been wearing spectacles for years, understanding your prescription can be a little confusing. With so many abbreviations and numbers, it’s easy to forget what it all means!

It’s important to have regular eye examinations; it is recommended to see an optician every 2 years unless you have been advised otherwise by your optician. Eye examinations can ensure you are wearing the right spectacle lenses for your vision needs and can also uncover any other health issues such as cataracts and glaucoma. With that being said, it’s key that you leave your opticians understanding the condition of your vision and what that means.

Your prescription is often displayed in some form of table, with various abbreviations, words and numbers to describe the outcome of your eye examination. So, if you need a helping hand in deciphering its meaning, look no further.

What does your spectacle lens prescription mean?

Your lens prescription will likely be made up of various abbreviations and numbers, which tells the optician more about your vision capabilities and if you need corrective lenses. The prescription will use ‘+’ or ‘-‘ signs to denote whether you are short or long-sighted, and how severely, which allows your optician to dispense the correct strength in the lens.

SPH (sphere)

There will typically be 5 different headings on your eye prescription, each of which will tell the optician about your vision and begin to build a picture of any vision problems. SPH (sphere) refers to the amount of lens power, and it’s measured in dioptres (D). There is likely to be a number as well as a ‘+’ or ‘-‘ sign. The higher the number, the stronger the prescription lens you require.


The AXIS measurement denotes the direction of your astigmatism, measured in degrees. It measures the orientation of the cylinder from 0-180 degrees and is a helpful measurement so that lab knows how to position your lenses to suit your vision needs.


PRISM refers to any correction needed to align your eyes. This is often required for any eye muscle weakness and can correct double vision. A number in this box typically means that your eyes need lenses to help them work better as a pair. Prismatic lenses bend the path of light, without altering focus, to achieve this correction.


The BASE measurement is related to the above prism indication and will specify the direction that the prism needs to redirect the light in.


If you are over 40 you might see ADD at the bottom of your glasses prescription. This is the reading addition to your prescription and often means you have presbyopia. The number will refer to the amount of correction required for seeing objects at closer distances. ADD is usually the same for both eyes and can range from +0.75 to +3.00.

Do I have a short-sighted prescription?

If you struggle to see objects at a distance, it’s likely that you might need lenses for short-sightedness. You can tell if you have a short-sighted prescription because the numbers on your prescription will be fronted with a minus (-) sign.

If the SPH measurement on your prescription reads -0.25, your prescription is not that strong, but a higher number like -6.00 can mean you have severe short-sightedness.


You might also see ‘OD’ and ‘OS’ written to the side of your prescription. These are simply abbreviations for ‘oculus dexter’ which is Latin for right eye, and ‘oculus sinister’ which is Latin for left eye.

Understanding your short-sighted prescription

There are different types of short-sightedness or myopia, which can help to better understand its severity. Severe short-sightedness is often referred to as high myopia, and it’s defined as -5.00 D or higher on your eye prescription. High myopia can put you at greater risk of health complications such as developing glaucoma, cataracts or retinal detachment.

You might also have progressive myopia, which continues to worsen over the years. This usually occurs in children but can continue into the adult years. There are some control methods that can help to slow down the worsening of short-sightedness, which can be beneficial for children.

Orthokeratology is a popular way to help improve vision without lenses, which involves wearing special contact lenses at night but taking them out during the day. Another revolutionary way of slowing down myopia progression in children is the brand new Stellest lens from Essilor.

Introducing Stellest lenses

In a two-year study, it was found that Stellest lenses could help to slow down myopia progression by 67% on average, compared to single vision lenses when worn for 12 hours a day.

Stellest lenses ensure children’s vision is corrected while slowing down any worsening of their visual abilities. This is so important, because the earlier you can control myopia progression, the less their vision will be impacted in the long run.

How to get a new glasses prescription

If you think you need a new eye prescription, you simply need to book an appointment to see your optician. They will be able to carry out a routine eye examination to check for any changes in your vision and glasses prescription. If you notice any difference in your vision or eye health, it’s important to book an appointment sooner rather than later, just to make sure there are no major problems.

If your glasses prescription has changed, your optician may dispense new lenses to help correct your vision more accurately. It’s important to wear the right eye prescription lenses to avoid any future problems like headaches and eye strain.

Can I get a glasses prescription online?

It’s not currently possible to get a prescription online, as your optician needs to use specialist equipment and determine the results from a number of different tests. If you’re hoping to check your vision in between your recommended eye exams, you can use our handy tool. Check Your Vision allows you to check individual eyes through a series of questions as you stand in front of a mirror. This may help to indicate correct and incorrect answers, and whether there are any visual symptoms.


It is still important to visit an optician every 2 years for a full eye examination, as they can also check for any visual health issues and ensure you are wearing the right lenses.

Take control of your vision with Essilor

If your next eye examination is due, why not ask about Essilor lenses? With lens solutions and enhancements for every vision need, we are the #1 spectacle lenses manufacturer worldwide(1)


1)     Euromonitor Eyezen 2019 edition, Essilor International SA Company. Retail value sales at RSP.

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