How do I read my contact lens prescription?
Please note a contact lenses
prescription is not the same as an eyeglass prescription. In addition
to your lens power, your contact leness prescription contains information relating
the size of the lens such as Diameter and Base Curve (B.C). You may also find your prescription
on the box of your contacts.Contact lens prescriptions vary based on the type of lens you wear (bifocal, toric, disposable contacts, etc.).
A typical contact lenses prescription looks like this:
|Eye||Power (Sphere)||BC (Base Curve)||DIA (Diameter)|
OS = Left Eye
- Power (Sphere):
The strength of contact lenses which is given as '+' or '-' with a numerical
value and a decimal point between -20.00 to +20.00.
- BC (Base Curve):
The Base Curve which is the inside curve of your contact lenses. This is a
figure with one decimal point, commonly 8.1 up to 8.9. This figure is usually
the same for both eyes.
- DIA (Diameter):
The Diameter of your contact lenses is a figure with one decimal point such
as 13.8, 14.0 or 14.5. The lens diameter fitted is usually the same for both
This is just for bifocal or multifocal lenses. It will be a number from +1.00 to +3.00 or be labeled high, medium, or low.
If your contact lens prescription is for a colored lens, the color selected would appear in this section.
- CYL (Cylinder):
Cylinder refers to the strength of you astigmatism. The values may range from -0.75 up to -9.75.
This is also for toric or astigmatism contact lenses, the axis of the correction are given in degrees and ranges from 10º up to 180º.
Astigmatism or Toric Lenses
If you have astigmatism, in addition to the above specification, you will also have CYL (Cylinder) and AXIS on your prescription. It will look like this:
This is how you order your astigmatism lenses online: