Take note of the information presented in a prescription, including: power, base curve, diameter and brand name. Bifocals and astigmatism prescriptions typically have additional information.
Learn the abbreviations used in a prescription:
- OS - for left eye
- OD - for right eye
- BC - for base curve
- PWR - for Power
- DIA - for Diameter
Look for additional abbreviations used for bifocals:
- ADD - for addtional power
- CYL - for cylinder
- AXIS - for astgmatism
Locate the prescription on the side of the box as seen below:
Read the measurement of the diameter (DIA), given in millimeters; this is the distance from one edge of the contact lens to the other.
Read the power (PWR) of the lens strength (it may be different for each eye), measured in diopters. The higher the power number, the stronger the prescription is. Look for a minus sign to indicate nearsightedness (myopia) and a plus sign that indicates farsightedness (hyperopia).
Read the base curve (BC) measurement in millimeters. The lower the number, the steeper the cornea of a patient's eye. If this measurement is not included, it is likely that the brand has only one standard base curve value.
Locate the brand name of the contact lens.