Understanding Your Optical Prescription

Making Sense of Your Glasses Prescription

Whether it's your first eye test, or you've been wearing glasses for years, the numbers on your prescription can sometimes feel confusing. One of the most common questions we hear is:

 "What do the numbers on my glasses prescription mean?

Understanding your prescription helps you make more informed choices when choosing the right frames and lenses - ensuring the perfect fit for your visual needs and lifestyle. 

This simple guide is explains the meaning behind each section of tour optical prescription, to make the numbers on your prescription make sense, so you can feel confident about what you're ordering.

💡Note: Your spectacle prescription is  is different to your contact lens prescription. Never order glasses using your contact lens prescription the lens power and measurements differ - this can affect your vision. 

Reading Your Glasses Prescription

Your prescription is often displayed in a table format, which may vary depending on your optician or the country where your eye test took place. Below are some examples:

Here are the most common terms on your glasses prescription and what they mean:

Sph (Sphere)

This value shows the lens power needed to correct long or short-sightedness.

• a plus (+) sign means you're long sighted (difficulty focusing on close objects).
• a minus (-) sign means you're short sighted (difficulty seeing far away).

Cyl (Cylinder)

This number indicates the degree of astigmatism, caused by slight differences in the curvature of your eye. If your optician mentioned your eyes are shaped more like a rugby ball, this is what they meant!

Axis

The axis works in partnership with the Cyl value - you can't have one without the other. 

It shows the angle (from 1 to 180) where the Cyl correction should be applied.The Axis doesn't affect the lens strength only orientation. 

Prism & Base

Prism is prescribed to correct eye muscle imbalance or double vision. The base value shows the direction in which the prism is applied (e.g. Up, down, in or our).

You may see prism values in one or both eyes and can vary in direction depending on the type of prism required. 

Near Add (Addition) 

The near add indicates how much additional power you need for reading and close work. It's added to your distance prescription to create reading glasses or varifocals. 

Int Add (Intermediate Addition)

The Intermediate Add (sometimes written as "Inter Add") relates to your mid-range vision, such as computer work or reading music. Not everyone will have this value listed - it's usually prescribed for those who spend significant time at middle distances

Still Unsure About Your Prescription?

We hope this guide helps you understand your glasses prescription more clearly. If you're still unsure about any part of it or need help interpreting your results, remember we're the experts and always happy to help.

📧 Email Us:  info@retrospectacle.co.uk

We'll help you make sense of your prescription and recommend lenses or frames that match your vision perfectly.