Contact lens prescription
Contact lens Prescription
A contact lens prescription is sometimes referred to as a contact lens specification. This contains information to ensure that your lenses fit you well, but also provide you with comfort and excellent vision.
After a contact lens aftercare you are entitled to a copy of your contact lens prescription. Contact lens prescriptions and glasses prescriptions are different so it is important that you have the most up to date prescriptions for both.
Do I need a prescription to buy contact lenses?
In the UK it is a requirement that you have an up to date prescription for both your eye test and contact lenses.
Why is it important to have a prescription?
There are a number of different types of contact lenses on the market. Some people may assume that if you know your power you can buy any contact lenses, this is incorrect. As each brand of contact lenses are made up of different materials and have different shapes it is important that you are fitted with the correct lenses to ensure they sit well on the surface of the eye and not cause any damage.
How long do contact lens prescriptions last for?
When issued with a contact lens prescription it will state the lens details as well as expiry date. Typically contact lens prescriptions last for 1 year, however this can be more or less depending on your opticians’ judgement. It is also important to check that your eye test prescription is in date, as you are unable to get contact lenses if your eye test prescription is out of date, even if your contact lens prescription is in date.
Interpreting a contact lens prescription
Below is an example of a contact lens prescription with the matching contact lenses. This will help you understand how to read a contact lens prescription.
Contact lens name: This is the name/brand of contact lenses you have.
D (Dioptre) / PWR (Power) / SPH (Sphere): This is the strength needed to correct your long or short sightedness. (+) is long sighted. (-) is short sighted
CYL (Cylinder): This is strength of the astigmatism you have. If you do not have astigmatism corrected lenses this will not be on your box/prescription.
AXIS: This is the direction the astigmatism is at. This number is typically between 0 and 180.
BC (Base curve): This is the curvature of your contact lens. The closer the curve of the contact lens is to the curve of the front surface of the eye, the better the lens will fit.
DIA (Diameter): This is the length of the contact lens from one edge to the other. It is used to ensure the contact lens covers the correct part of the eye.
ADD (Additional power): this can be found on multi-focal contact lenses, this number identifies the reading power of the contact lens to help with close work.
Expiration date: The expiration date is similar to a “best before” date which is found on food packaging. This is not related to the expiry date found on a contact lens prescription. It is purely written to indicate when the contact lenses should be used by.