What Does My Glasses Prescription Mean? A Simple Guide

Published 18 August 2026 · Visionwise Opticians

Ever looked at your glasses prescription and wondered what all those numbers actually mean?

SPH, CYL, AXIS, ADD… an optical prescription can look confusing, but it’s actually much simpler once you know what each part represents.

In this guide, we’ll explain how to read your glasses prescription, what the numbers mean, and whether your prescription indicates myopia, hyperopia or astigmatism.

SPH – Sphere

SPH (Sphere) tells us the main focusing power your eyes need. It is measured in dioptres (D).

One of the first things to look for is whether the number has a minus (−) or plus (+) sign.

Minus prescription = Myopia

If your SPH has a minus sign, such as:

−1.00, −2.50 or −5.00

you are short-sighted, also known as myopic.

Myopia usually means you can see more clearly up close, while objects further away appear blurred.

Generally, the larger the minus number, the stronger the correction required. For example, someone with a prescription of −5.00 is more short-sighted than someone with a prescription of −1.00.

Plus prescription = Hyperopia

If your SPH has a plus sign, such as:

+1.00, +2.50 or +4.00

you may be long-sighted, also known as hyperopic.

Hyperopia means the eye needs additional focusing power. Depending on your age and prescription, this can affect near vision, distance vision or both.

Again, a higher number generally represents a stronger prescription.

CYL & AXIS – Astigmatism

If your prescription contains numbers under CYL and AXIS, you have some degree of astigmatism.

CYL (Cylinder) tells us how much astigmatism needs correcting.

AXIS tells us the orientation of that correction and is written as a number between 1 and 180 degrees.

For example:

SPH −2.00 / CYL −1.00 / AXIS 90

This indicates a short-sighted prescription with astigmatism.

Astigmatism is extremely common and simply means the eye has different focusing powers in different directions.

What does ADD mean on my prescription?

ADD stands for addition.

This is additional focusing power required for near tasks such as reading and is commonly prescribed as we get older due to presbyopia.

For example:

Distance SPH: −2.00
ADD: +2.00

The ADD can be incorporated into reading glasses, bifocals or varifocal lenses, depending on your visual needs.

What does PRISM mean?

Some glasses prescriptions also contain prism.

Prism is different from the usual sphere and cylinder correction and may be prescribed to help with certain eye alignment or binocular vision problems.

Not everyone requires prism, so it’s completely normal for this section of your prescription to be blank.

What type of glasses prescription do I have?

Here are a few simple examples:

−3.00 SPH
Myopia / short-sightedness

+2.00 SPH
Hyperopia / long-sightedness

−2.00 SPH / −1.00 CYL × 90
Myopia with astigmatism

Plano SPH / −1.50 CYL × 180
Astigmatism without a spherical prescription

ADD +2.00
Additional power for near vision / reading

Your glasses prescription is only one part of understanding your vision. Your optometrist will also consider your age, symptoms, eye health and how your eyes work together when recommending the most suitable glasses and lenses.

Still confused by your prescription?

Don’t worry — that’s what we’re here for.

At Visionwise Opticians in Glasgow, we’re always happy to explain your prescription in plain English and help you understand the lens options best suited to your vision, lifestyle and budget.

Due an eye test? Click the button below to book your appointment online.

visionwise. — your vision is our vision.