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 no older than 1 year, as your eyesight can change in this time. Note that the values of your glasses and contacts differ for the same correction.
How to read your correction values:
The sphere indicates the strength of the contact lenses. A plus (+) symbol can be found in front of the value if you are farsighted and a minus (-) if you are short-sighted. Please pay attention to the symbol when placing your order. Should there be no symbol, this usually indicates a plus (+) value.
Base curve (BC)
The base curve indicates how the lenses are curved. Contact lenses normally have a curve between 8.3 and 9.0 mm.
The DIA value denotes the diameter of the lenses, in mm.
Cylinder (ZYL/ CYL) – Only relevant for those with corneal irregularities.
This is only relevant for those with corneal irregularities. The cylinder indicates the height of the corneal curvature. Note previous such values when ordering. Should there be no symbol noted, this then indicates a plus (+) value.
Axis (A/ACH) – This is only relevant for those with corneal irregularities.
The axis is expressed in degrees and defines the alignment of the required cylinders for the correction of corneal irregularities. You will need this so that your lenses are properly aligned. The axis is always between 0° and 180°.
Addition (ADD) – Only relevant for varifocal glasses.
The addition (ADD) denotes the strength of your lenses, in addition to the distance correction. This is relevant for those who also need assistance when seeing things in close proximity, e.g. when reading. This value is always positive and is often identical in both eyes.