Prescription Queries

It is recommended that everyone attends an eye test at least every two years. Contact lens wearers need to attend an additional check-up to ensure their lenses still meet their prescription; this is usually every 12-24 months dependent on the recommendation of your optician.
We would advise that you speak to your optician about changing the type of lenses you wear. However, our optician has put together a list of compatible and upgrade lenses for all contact lenses. So you can see what the compatible monthly or daily would be for your current lens and discuss this option with your optician.
All contact lens prescriptions include a least three values: base curve, diameter and power. However for toric or multifocal lenses additional values will be added to the prescription, usually no more than four.
The specifications you can expect to see are as follows:
Base Curve (BC): The curvature of the lens in millimetres usually between 8.3 and 9.0.
Diameter (D): The diameter of the contact lens. This number ranges from between 13.8 to 14.5.
Power (PWR/SPH): Is a + or - figure followed by a number e.g. -4.50 or +0.25. This represents the level of visual correction needed, and whether your lenses correct long-sightedness (plus/+ powers) or short-sightedness (minus/- powers). For some contact lenses the power may also be 0.00, plano or displayed with this symbol ∞ which is for non-prescription use e.g. coloured contact lenses.
If you have astigmatism the following values will also be required:
Cylinder (CYL): A minus number that increases in a scale of 0.25 dioptres, ranging between -0.25 to -2.75.
Axis (AX): A number between 0 and 180, that determines the direction needed to correct your astigmatism.
If you wear multifocal contact lenses the following values will also be required:
Addition (ADD): A + number between 0.50 and 3.00, or referred to as high, medium or low. This is an additional power that determines the level of correction needed for you to focus on near objects.
Dominant (D): A choice between "D" and "N" to determine which is the dominant and the non-dominant eye.
Your contact lens prescription or lens specifications are printed on the end or side of your contact lens box and labelled on the top of the blister packs that contain your lenses. Your optician will hold a copy of your written prescription; you are legally entitled to have a copy of this once you have completed your initial contact lens trial.