A contact lens prescription varies slightly from an eyeglass prescription. Normally, the contact lens prescription is valid for one year. Because of the way the circle lenses are used, the power of the contact lens differs from that of the glass. The technical term used to describe the optical system of lenses closer to the eyes is “effective.” A circle Contact lens prescription also contains additional information related to the measurement of the lens. The contact lens box contains information on a left eye as well as the right eye and a doctor’s prescription also contains information for both the left as well as the right eye. Measurements of the base curve, vary from brand to brand, some contact lenses come with a wider base while other with a narrow base.
A new prescription will be needed if you change the brand of your circle contact lenses. Prescription may include instructions on how long you can wear the lenses for a given time. The provision of prescription may vary, but all terms, abbreviations and measurements are universal. Things you need to know about the prescription of circle lenses is provided in detail along with the instructions on how to read them.
• OS (Oculus Sinister) refers to the prescription for the left eye. OD (Oculus Dexter) refers to the prescription for the right eye. OU (Oculus Uterque) means the prescription can be filled by one eye.
• PWR (Power) is the amount of correction required is measured in diopters. The range is from -20.00 to 20.00. A negative number means myopia or nearsightedness; positive number indicates hyperopia or farsightedness.
• BC (curve) measures the size of the light needed to cover an eye. The range is from 8.0 to 10.0 mm.
• DIA (diameter) refers to the width of the lens. The range is from 13.0 to 15.0 millimeters.
• MARK is the name of the manufacturer of a specific goal
• COLOR (optional) refers to a specific type of lens. Visibility tints are not prescription lenses alter eye color. The colored lenses are easily identifiable are stored in cases. Enhancers modify the natural eye color slightly. Contacts will be opaque lighten, darken or completely alter the natural eye color.
• ADD (Add power) is an additional correction for reading or close the specific display for bifocal contact lenses. Power always assumed to be positive, although not listed in the prescription.
• CYL (cylinder) is a measure used for toric lenses, which are worn by people with astigmatism. The ranges from -0.75 to -10.00 and is measured in diopters.
• AXIS is another measure used to toric lenses. The range is 0 to 180 degrees Measuring how many contact lens must rotate to compensate oval instead of round shaped eyes (astigmatism).
These are some of the most common codes used in almost all the circle lens prescriptions and are the same throughout the world wherever you go.