What Do The Numbers On Your Prescription Mean?
- Mar 25
- 2 min read
If you’ve ever looked at your eye prescription and felt unsure what it all means, you’re certainly not alone. The mix of letters and numbers can seem confusing at first glance, but they’re simply there to help ensure you receive the clearest, most comfortable vision possible.
This guide breaks everything down into plain, easy-to-understand terms.
What is a prescription?
Your prescription is a set of measurements taken during your eye test. It tells your optician exactly how your lenses should be made to suit your eyes.
Everyone’s eyes are different, so each prescription is unique to the individual.
SPH (Sphere)
This is your main lens strength.
A minus (-) value means you may find it harder to see things in the distance (short-sightedness)
A plus (+) value means you may find close-up tasks more difficult (long-sightedness)
The higher the number, the more correction is needed.
CYL (Cylinder)
This relates to astigmatism, which is very common.
It simply means the eye isn’t perfectly round, which can cause slight blurring or distortion. The CYL value corrects this so your vision appears clearer and more even.
AXIS
This works alongside the CYL value.
It shows the direction of the astigmatism, helping ensure the correction is placed in exactly the right position.
ADD (Addition)
This is extra support for near vision, such as reading.
It’s often needed as we get older and find it harder to focus on things up close.
PRISM
Prism is included if your eyes need a little help working together.
It can improve comfort and reduce symptoms such as eye strain or double vision.
BASE
If prism is prescribed, the BASE tells us the direction the correction should be applied, ensuring your eyes align comfortably.
In simple terms
Your prescription helps your optician understand:
How strong your lenses need to be
Whether your vision needs fine-tuning
If you need help with reading or close work
How well your eyes work together
A final word
Understanding your prescription can help you feel more confident about your eye care and the choices available to you.
If you’re ever unsure about any part of your prescription, don’t hesitate to ask your optician - they’ll be more than happy to explain it and guide you through your options.
Clear, comfortable vision plays an important role in everyday life, and the right support can make all the difference.
