What Values Do I Need to Purchase Contact Lenses?
When purchasing contact lenses, we require your current correction values. You will find these on your old contact lens package. It is important that your values are not older than 1 year, as your eyesight can change in this time. Please note glasses correction values and contact lenses values are different for the same correction.
Here's how you can read your correction values:
The sphere indicates the strength of the contact lenses. Before the value stands a plus if you are farsighted, or a minus if you are nearsighted. Please pay careful attention to the symbol when placing your order. Should there be no symbol, typically this indicates a plus value.
Base curve (BC)
The base curve indicates how sharply the lenses are curved. Typically contact lenses have a curve between 8.3 and 9.0 mm.
The DIA-value gives the diameter of the lenses, in mm.
Cylinder (ZYL/ CYL) – Only relevant for those with corneal irregularities.
The cylinder indicates the height of the corneal curvature. Please be aware of the preceding symbols during your order. Should no symbol be given, typically this indicates a plus-value.
Axis (A/ACH) – Only relevant for those with corneal irregularities.
The axis is expressed in degrees and describes the orientation of the required cylinders for correction of corneal irregularity. It is required in order to be able to properly align your contact lenses. The axis is always between 0° and 180°.
The addition (supplement) describes the strength of your contacts that, in addition to the distance correction, need to assist with seeing in close proximity; for example, when reading. This value is always positive and is most often identical in both eyes. As a result, it is commonly only given once.