How do I read my glasses prescription?
After an eye exam, your optician will give you a copy of your prescription. By UK law, they are required to give this information to you and if they haven’t, you should ask for it. Once you are given your prescription, it can be difficult to understand what the words and numbers mean. We've broken down the different parts of your prescription to make things easier.
What do the symbols on my prescription mean?
Sphere (SPH) /+ or –
The number which follows the + or – sign.
‘+’ means you are long-sighted
‘-‘ means you are short-sighted
Sometimes you’ll find the + or- sign written above the number.
It is measured in dioptres, going up in steps of 0.25.
Sometimes you’ll notice there is Plano, PL Infinity (∞) or 0.00, which all equal to zero. No visual correction is required.
ADD
This is the additional correction required for reading
Also written as near addition or NV – it is required for reading.
An ADD can range from +0.25 to +3.50. (It goes up in steps of 0.25).
Cylinder (CYL)
Cylinder number refers to how mild or severe your astigmatism is.
An empty box or DS means there is no astigmatism or its too small to require correction.
Astigmatism can range from +/- 0.25 to +/- 2.00
OS and OD
OS means left eye and OD means right eye.
AXIS
Axis indicates the position of the cyl and can range between 1-180.
Prism
This shows if you have a muscle imbalance in your eye and is prescribed to prevent headaches or double vision. (We don’t offer Prism correction at this present of time.)
The prism is written in fractions (e.g. 1 ½).
PD (pupillary distance)
Measures the distance between your eyes, from the centre point of one pupil to the other.
In most cases your optician will not add this to your prescription.
Other symbols
Other symbols which you may find include BAL (balance), VA (visual acuity) and BVD (back vertex distance).
VA and BVD will not be required to place your order.
General top tips for entering your prescription
- Don’t mix up + and – values on sph and cyl values
- Axis values are exactly entered as they appear – don’t enter 15.5 if stated 155 on prescription.
- Reading glasses: don’t forget ADD (Near Add, NV Add) if there is one stated
- Computer glasses: you may find an Intermediate Add (also Inter Add or Int Add) Please use this to order your glasses for computer.
Most common prescription layouts from opticians
The examples below show various prescriptions from opticians alongside examples of how these prescriptions should look when entered on our website.
Specsavers
It would be entered on our website as follows:
Please note: The ADD value (Near-ADD and Inter-ADD) won't always be mentioned on your prescription, in this case please leave it blank when you enter your prescription on our website.
Sometimes the Near Add and Intermediate (Inter) Add will be worked into the prescription rather than being displayed separately.
In this example, the full intermediate and reading prescriptions have been provided.
To order glasses for computer, please enter the full intermediate prescription.
To order glasses for reading, please enter the full near prescription.
Specsavers
It would be entered on our website as follows:
Please note: You do not need to enter the BVD value if it is mentioned on your prescription.
Specsavers
It would be entered on our website as follows:
If you are entering a prescription for distance, the Add does not need to be entered.
On occasions, your opticians may not write Sphere (sph) Cylinder (cyl) or Axis on your prescription.
Vision Express
It would be entered on our website as follows:
Please note: If you would like to order glasses for distance you do not need to enter the ADD value.
Boots
It would be entered on our website as follows:
Please note: You do not need to enter the Distance acuity and Near acuity if it is mentioned on your prescription.
Hospital
It would be entered on our website as follows:
NHS
It would be entered on our website as follows:
NHS Scotland
It would be entered on our website as follows:
Please note: The cylinder (CYL) value is written in a plus (+) format, make sure to select plus (+) instead of minus (-).
David Clulow
It would be entered on our website as follows:
Please note: If you would like to order glasses for distance you do not need to enter the ADD value.
Other symbols
You might also find the following symbols on your prescription:
Balance or BAL Balance or bal refers to the prescription in that particular eye and means that no values are needed for that eye. The lens for this eye is made to the same weight so that the glasses feel balanced when on the face.
Here is an example of how balance would look on a prescription besides how it would be entered on our website:
Please note: If you would like to order glasses for distance you do not need to enter the ADD value.
DS
DS stands for diopter sphere, which means a spherical correction. If this is left blank, then there is no astigmatism (cylinder and axis) that requires correcting.
Dixon Hempenstall Opticians
It would be entered on our website as follows:
Please note: If you would like to order glasses for distance you do not need to enter the ADD value.
Plano, PL, ∞
Plano, sometimes referred to as PL or the infinity symbol (∞), means that no visual correction is required.
You may also find these under the sphere section.
Here is an example of how Plano would look on a prescription besides how it would be entered on our website:
Please note: If you would like to order glasses for distance you do not need to enter the ADD value.
Can I use my glasses prescription for contact lenses?
The prescription you are given for your glasses and the one you are given for your contact lenses are different. They should not be used interchangeably as contact lenses sit on the surface of the eye and glasses are flatter and sit further away from the face.
What types of lenses are there?
Depending on how your vision needs to be corrected, you will be prescribed a certain type of lens. The different type of lenses include:
- Single vision lenses-have one power across the lens and are used to correct short-sightedness (myopia), long-sightedness (hyperopia) and astigmatism
- Bifocals-contain two different prescriptions within the lens and are used to see objects both near and far from you
- Progressive lenses/varifocal lenses-also known as multifocal lenses, these lenses have three prescriptions within the lens and are used for close-up work (e.g. reading a book), middle-distance work (e.g. looking at computer screen) and distance viewing (e.g. driving)
Does FGC accommodate lenses for all prescriptions?
We do a wide variety of prescriptions; however, we are unable to do very strong or very high prescriptions. The combined sphere and cylinder (cyl) values cannot be greater than a minus 8 or a plus 6, with the cyl value not being over plus 2 or minus 2.
Please also note, we offer single vision lenses only.
You should now have a better understanding of what your eyeglass prescription means which will help you select the right optical glasses for you and your visual requirements.
If you have any questions regarding your prescription and choosing the right optical glasses for you, please do not hesitate to contact our helpful optical team by calling 0800 458 2090 (Free) or emailing cs@feelgoodcontacts.ie