Understanding your prescription is very important if you’re ordering contact lenses online – you will need to know your requirements to order the correct contact lenses. Your prescription should be given to you by your optician/optometrist after a contact lens fitting. Remember, you have the legal right to request a copy of your prescription. If you’re already using contact lenses with the correct prescription, you can also find the information written on the side of your contact lens box.
The vision in your eyes may vary, so your left and right eye will be listed separately.
There are a few different figures on your prescription – here’s a quick guide to understanding them:
(BC) Base Curve – This is a measurement of the curvature of the contact lens. Always done in millimetres, this figure determines how well a contact lens will fit the eye.
(DIA) Diameter – This is the width of a contact lens measured in millimetres.
(PWR/SPH) Power/Sphere – This figure indicates whether you are long or short-sighted, and how weak your vision is. Long-sightedness is indicated by a plus (+) and short-sightedness by a minus (-). The higher the figure, the greater the visual correction.
(AX) Axis – An axis indicates the direction of the curve needed to correct an astigmatism. It will be a number between 0-180 and is only found in toric lenses.
(CYL) Cylinder – This figure is only present on toric prescriptions for astigmatism and determines the power of astigmatic correction.