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How To Read Your Prescription

How To Read Your Prescription

Often, prescriptions will be written in a variety of ways that can often be confusing. Here, we will outline how to read your prescription and pick out the parts that are needed when ordering your glasses online.

What do OS and OD mean?

Most opticians will write 'left eye' or 'right eye' when writing the prescription for each eye, but the terms 'OS' and 'OD' can also be used. OD is referring to your right eye, and OS is referring to your left eye.

What is a Sphere (SPH)?

The first thing that will probably be written on your prescription is the 'SPH' or 'sphere'. There should be one for each eye. The SPH is the correction for long or short-sightedness. The number will be written in .25 steps and will be preceded by a plus (+) or minus (-) sign.

A plus in front of the number indicates long-sightedness, which is called hyperopic, and is when someone has difficulty focusing on close objects. A minus sign indicates short-sightedness, called myopia, and is when a person has trouble focusing on distant objects. This number will sometimes be 0.00 which indicates there is no long or shortsightedness issue with the eye.

When ordering online it is important to make sure you have entered the correct plus or minus, as getting these mixed up will cause the glasses to make your vision worse and they will have to be replaced. Please double-check whether your prescription is plus or minus and enter it correctly. Each eye may have a different number, and one may even be longsighted while the other may be shortsighted.

What are the CYL and AXIS?

Next is usually the 'CYL' or 'cylinder', as well as 'AXIS'. This refers to those with astigmatism when the eye is shaped slightly more like a rugby ball and less like a perfectly spherical football. The eye is called toric in this instance. The CYL refers to how bad the astigmatism is, and again goes up in .25 increments and can be either plus (+) or minus (-), so please make sure you double-check this is correct. The axis refers to what angle astigmatism lies, ranging from 0 to 180. This can go up in 1/2 measurements so please contact us directly if yours does so.

Reading Addition

A reading ADD will sometimes be present. This is the indication of how much extra power is needed on top of the main distance prescription for reading glasses, varifocals, and bifocals. Mostly, this will not be present. When it is, however, it will only be one number for both eyes. The numbers, again, go up in increments of 0.25 but will always be preceded by a plus (+) sign.

For Those With a Prism Reading

If there is a 'PRISM' number written on your prescription, then it is best to deal directly with your opticians. Having a prism is very rare but is delicate so it will need to be dealt with an optician in person. Having a prism simply means your eyes do not work in sync together. However, your prescription will correct this issue as well as help with other side effects such as headaches and double vision.


This section is for the lab, the Base tells the lab technicians where to put the prism in your glasses.

How do I add my prescription at Fashion Eyewear?

At Fashion Eyewear you can add your prescription to our luxury optical glasses and designer sunglasses. It may be strange to add your prescription to an online optician but our step by step checkout makes it easy. You simply follow the stages and choose the lens brand (Essilor, Nikon, Oakley, Ray-Ban, Maui Jim and our standard packages) then choose the relevant coatings and tints to your glasses. Remember choosing your lens type along with coatings are made to suit your lifestyle, to personalise your glasses to your individual choice. After choosing your lenses you can then add your online prescription. Simply fill in all the sections which are available on your prescription for our optician and lens technologists. One section, however, will be missing and that is your PD. However, we have a PD in the inbuilt system to our website which allows us to measure your pupillary diameter from home - simply with the use of your webcam!

The next step is to add your delivery and wait for the arrival of your new designer eyewear!

If you have any questions our happy customer service team is eager to help via phone, email or live chat!

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