Prescription Help

Understanding your prescription

Your prescription is split into three sections, Sphere, Cylinder and Axis. You will most commonly see this written as, Sph, Cyl and Axis.

There are simple rules for each part of the prescription

Sphere – Is always a number in 0.25 jumps (i.e. 0.25, 0.50, 0.75, 1.00, 1.25). This can either be written in minus or plus (- or +).

IMPORTANT: You must select the correct symbol when ordering (minus or plus, – or +) as selecting the wrong sign will create the completely wrong prescription required to correct your vision.

Cyl – Is always a number in 0.25 jumps (i.e. 0.25, 0.50, 0.75, 1.00, 1.25). This can either be written in minus or plus.

IMPORTANT: You must select the correct symbol when ordering (minus or plus, – or +) as selecting the wrong sign will create the completely wrong prescription required to correct your vision.

Axis – Is a number between 0 and 180, it can also be written to point five (0.5) of a degree. This simply happens if the optometrist can’t decide wether you prefer for example 79 or 80 so they simply write your axis as 79.5. In this case lets get your glasses as accurate as possible so please provide us with the 79.5.

The in instances when a prescription doesn’t have a value for the Cyl section please leave the Axis blank (or some opticians write this as 0.00), the Axis is indicating what degree the Cyl figure sits at so if there is no Cyl there is no Axis required.

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Other symbols which are often seen written in a glasses  prescription

Infinity Symbol  – this is another way of writing zero (no prescription) so simply select 0.00 into the corresponding section for either sphere or cyl.

Plano – this is another way of writing zero (no prescription) so simply select 0.00 into the corresponding section for either sphere or cyl.

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What is the Add (Addition) part of my prescription?

You typically start to get the add part to a prescription when you hit 40+ and it is a measure of the amount of magnification you require to read.

The add is a plus (+) power which identifies how much extra addition (magnification) a glasses wearer requires (on top of their distance prescription) in order to read comfortably at close up distances, such as reading.

If you require reading glasses you take the addition value and add it onto the Sphere value of your distance prescription.

At extreme-eyewear.co.uk we currently only do single vision distance or reading eyewear. This is simple because as dispensing opticians we feel the technology available is not good enough to accurately measure a customer for varifocals as extra height measurements are required. Although we agree we are cheaper than the high street so you would prefer to purchase from ourselves we must always put our customers vision first.

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