About Your Prescription

Before ordering your glasses online you will need your prescription from your most recent eye test. You will be asked to enter it during the ordering phase. If you don’t have your prescription, please contact the Opticians where you had your last eye test.

It is recommended that your prescription should be under 2 years old (or under 1 year old if you are over 70). This is to ensure it is as accurate as possible as your eyesight may change over time.

Understanding Your Prescription

Below are examples of prescriptions commonly given:

Measurements are specific for each eye. Please take care to enter the measurements exactly as shown on your prescription.

SPH (Sphere): This indicates how long or short sighted you are. Normally a + sign denotes long sight, and a – sign denotes short sight. On some occasions the SPH value will read PLANO (or show the infinity symbol). If this happens on your prescription, select 0.00 when entering the SPH value.

CYL (Cylinder): A CYL value indicates astigmatism (where the back of your eye is shaped like a rugby ball rather than a football). If the CYL is 0 or blank on your prescription, select 0.00. If your prescription has a CYL it will also have an AXIS.

AXIS: This indicates the direction of astigmatism if present. It is measured between 0 and 180 degrees and denotes the angle at which the lens is set into the frame. Your prescription will only contain an AXIS if it includes a CYL.

PRISM: This corrects a muscle imbalance (squint)

BASE: This denotes the direction of the PRISM (UP, DOWN etc)

ADD: Some prescriptions will have a near ADD. This is for patients who require glasses for both distance and reading. The ADD value is added to the SPH value to calculate the value for the reading part of bifocal/varifocal lenses. Please note that you will not be able to enter an ADD value as we only sell single vision glasses online.

P.D. (Pupiliary Distance): The PD is the distance between the pupils of your eyes. This is measured in mm and is a very important measurement. The average for a male is 63mm and for a female 61mm. Your PD will usually be measured as part of an eye test but may not be recorded on your prescription. Please ensure you ask your optician for this or ask for it to be added to the prescription. Alternatively you can attempt to measure your PD yourself. To do this, stand in front of a mirror with a felt-tipped pen. On the mirror, place a dot where the centres of your pupils are and measure the distance between the dots in mm. You will need to provide your PD when ordering online.

`Measure your PD

If you have any questions or need any help regarding your prescription please contact us on 01778 421188 or by email.


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We provide sight tests at our eye centre in Bourne. Private and NHS eye tests available.




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