How To Read Your RX

We believe ordering contact lenses online should be a quick and painless process.We know that you know your prescription and trust that you have an up-to-date copy at hand. And, even if you haven’t got a copy and can’t remember your prescription figures, you’ll be able to find them printed on the side/end of your most recent box of contact lenses.

What is my contact lens prescription?

A contact lens prescription will list all of your visual requirements, telling you which type of contact lens you need to purchase. We understand that all these figures won’t make much sense to look at if you don’t know what they’re for and what they represent. That’s why we’ve created this guide on prescriptions and all you need to know when you order contact lenses online.

Before we get started, it’s vital to remember that a prescription for contact lenses is entirely different from a glasses prescription, meaning if you want to switch from glasses to contacts, you’ll need to visit your optician for a lens fitting to receive a copy of your contact lens prescription.If your optician hasn’t provided you with one after your last lens fitting, don’t hesitate to request one.

What do the figures on my contact lens prescription mean?

 

Base curve (BC) – This figure, measured in millimeters, determines the curve of the lens. This has been identified to fit the curvature of your eye, and is sometimes written alongside the terms: flat, median or steep.

 

Diameter (DA) – This figure simply tells you the required width of the contact lens, and is again given in millimeters.

 

Power/Sphere (PWR/SPH) – The strength of visual correction required is given by the Power or Sphere figure. A minus sign before the number (-) indicates that you are short-sighted, while a plus sign (+) is used for long-sightedness. The higher the number, whether a minus or a plus, the stronger the power/sphere is.

 

Prescription figures for astigmatism

 

Axis (AX) – Toric contact lens prescriptions for people with astigmatism feature an axis figure that indicates the direction of the cylinder power and is given in degrees between 0 and 180. These lenses are designed for people with an unusual curve to their eye.

 

Cylinder (CYL) – Specifically for toric lenses, this figure indicates the extra power required to correct the astigmatism of the lens wearer.

 

Prescription figures for presbyopia

 

Addition (ADD) - Used for multifocal contact lens prescriptions, the Addition figure represents the level of correction that the wearer needs for clear vision at short distances. Given as a figure between 0.50 and 3.00, the ADD is sometimes referred to as low, medium or high.

 

Dominant (D) - Visual correction through multifocal contact lenses is ensured through a ‘dominant’ and ‘non-dominant’ eye. ‘D’ and ‘N’ are figures used to denote which eye is which, respectively.