How to read your prescription
What do the numbers and words actually mean on your prescription?
Base Curve
BC stands for ‘Base Curve’, this describes how curved the contact lens is, the curve is designed to fit comfortably over your cornea without moving too much.
Diameter
This is the Diameter or width of the lens in millimeters.
SPH (sphere)
This could also be labelled on your lens packaging as PWR or D.
The sphere power in a contact lens is used to correct either short sight ( - minus powers) or long sight ( + plus powers).
Your glasses prescription and your contact lens prescription will usually have slightly different numbers for the Sph, Cyl and Axis. This is because the glasses sit away from your eye and your contact lenses sit directly on your eye, this changes the amount of power needed.
CYL (cylinder)
This is a measurement of the amount of astigmatism corrected by the contact lens. Astigmatism is a visual distortion caused by an irregular shape of the cornea. Some astigmatism can be corrected by the regular shape of the contact lens, that means that sometimes you might have ‘cyl’ in your glasses prescription but not in your contact lens prescription. If you need a specific correction for astigmatism in your contact lenses they will sometimes be called ‘Toric’.
AXIS
This shows the direction that the toric contact lens needs to point or orientate to correct your astigmatism. Often Toric contact lenses have a small line marked on the lens, you can use this line when putting a toric contact lens in your eye to help the lens sit correctly more quickly, if you cant see a line don’t worry they are designed to rotate into place as you blink and should fully settle within 5-10 mins of wear.
ADD
As your eyes mature you will likely need some help with close work like reading. This change is natural and can be corrected by incorporating an ‘add’ (some + plus power) to your contact lenses, these contact lenses are called ‘multifocals’. Some lenses will record the ‘add’ as a number such as +1.50, others use an add type such as Low, Medium or High, or Distance (D) or Near (N). Some multifocal contact lenses don’t need an add or add type, that’s normal and you won't be asked for it when ordering.
DOs & DON’Ts of buying online
We've all been there, found a great deal online only to have a different product arrive and no customer service to help. At Specsavers we like to do things a little different and offer a great online service supported by our friendly Australian call center and over 350 high street stores for when only talking to a person will do.
When buying contact lenses online use the following advice to make the process a bit smoother:
DO
If you currently use a specific brand, you should stick to it. You should only ever change the lens you use based on advice from your optometrist.
DON’T
We don’t recommend that you buy your contact lenses from ‘just anywhere’. Look out for a well-known supplier you’re familiar with, and read a few brand reviews before you buy anything.
Make sure you have the following lens information:
- The brand
- Name of the lens
- Power
- Cylinder (if any)
- Sphere
- Axis (if any)
- Base curve
- Power
- Diameter
- Peripheral curves (if any)
