How to Read an Eye Prescription in the UK

It’s not only common to wear glasses or contact lenses in the UK, it can also be something that actually makes your look and style improve! But before you can choose from our stunning designer frames, you’ll want to take an eye test to determine how strong your lenses need to be and whether there is anything specific about your eyesight needs. 

However, even though getting an eye test with one of our expert opticians couldn’t be a more simple and straightforward experience, it can be tricky to understand exactly what your eye test prescription actually means. Many of our patients ask us these questions, so we thought it would be a great idea to write some clear guidance to remove the mystery behind the language on a prescription. 

What is a Strong Prescription?

When one of our opticians carries out an eye test, they go through a number of checks, both to work out how your eyes work on their own, but also how they work in tandem. One of the tests they do is to look at whether you are short-sighted, or long-sighted and then just how much correction is needed in either case. 

The prescription will have on it a value of short-sighted or long-sightedness and the required corrective power of the lens that is needed. The higher the number then the stronger the prescription is. This number on its own might seem quite arbitrary but it is actually the measurement in diopeters, and the more diopeters, the stronger the prescription. 

It’s difficult to say what exactly counts as a strong prescription, but up to about 6.00 diopeters is a mild to moderate need for correction, and 6.00+ is where the required power of the lenses gets to be higher. 

What is a Plus and Minus in Eyesight?

The plus and the minus is a very simple way of demonstrating on the prescription whether the eye test has revealed long or short-sightedness. If you see a + symbol on yours, then it shows that you are long-sighted, and a – symbol shows that you are short-sighted.

These symbols will often be placed alongside the number of diopeters to demonstrate just how long or short-sighted the eye test has revealed the patient to be. For example, a prescription that reads – with the number 8.00 would reveal quite strong short-sightedness. 

What is the Difference Between Long and Short-Sighted?

There are a lot of different aspects of your eyesight that the eye test will reveal, but perhaps the question our patients most commonly ask is what the actual difference is between long and short-sightedness.

Those of us who need lenses to correct long-sightedness will find that we struggle to see things when they are relatively close to our faces. As you are unable to see objects that are near to you this can be quite a problem if you are struggling with this then you should visit us at David Paul Opticians. This can cause mild health problems like headaches as many sufferers have to squint to see clearly. 

When one is short-sighted, the eye test will pick up on this through the classic eye charts that many people are familiar with. People who have this problem will find it more difficult to see things that are at a distance from them, and this may be noticeable to the patient when they find themselves holding their phone or a book closer to their face to be able to read properly. 

You may experience eye strain or headaches as a result of either condition, so visiting an optician is a good place to start. 

What is SPH, CYL and Axis in an Eyecare Prescription?


SPH means ‘Spherical Number’ and this is the section on a prescription where you’ll find the plus or minus symbol, as well as the number in diopeters. The sphere in question indicates whether the lenses will be required for short or long distances. 


CYL stands for cylinder, and this is where your eye test prescription will pick up on whether the patient has astigmatism. Like SPH, there will be a number following the CYL which indicates the degree of any detected astigmatism. 

Astigmatism can cause mild blurry vision and some strain and develops when light focuses more in one place on the eye than another. The eyeball is typically spherical but the more astigmatic a person is the more conical their eyes are. 

If you don’t have astigmatism then you can expect this column to be left blank. 


Like CYL, you will not see a number written in Axis unless you have astigmatism as it relates to the angle at which the astigmatism sits. This number will be written in degrees from 1 to 180, and it is not uncommon to have some very mild astigmatism. 

Should I Get My Eyes Checked?

Unfortunately many of us do experience poor eyesight, and things can develop and change with age as well as the result of an underlying condition. Many people put off going to the opticians because they think they can carry on with their day to day activities well enough, but getting your eye health checked out by one of our expert team can have a huge positive impact on your life. Regaining perfect vision through a prescription will save you lots of problems in the long run. 

It’s important to go for an eye test regularly, as problems can worsen over time and your sight is hugely important to much of what we do in our modern lives. Our patients can rely on us to provide an excellent service, both during the examination itself and at the process of picking frames. There are a host of issues that you may find you can resolve with an appointment at David Paul. Why not get in contact with us today and book yourself an appointment with one of the team?