Contact Lens Prescription Terms
O.D. (Oculus Dexter)
- Latin for “right eye”.
O.S. (Oculus Sinister)
- Latin for “left eye”.
BC (Base Curve)
- A number between 8 and 10 that measures the curve of the lens.
DIA (Diameter)
- The width of the lens in millimeters. Typically between 13.5 and 15 millimeters wide.
Power/Sphere (PWR/SPH)
- The strength of your prescription. It will have either a plus or minus sign before it depending on whether you are nearsighted (-) or farsighted (+). Plano (PL) means 0.00.
Cylinder (CYL)
- This helps correct astigmatism. It is written with a minus sign.
Axis
- This is required if you have astigmatism. It is a number between 0 and 180.
Add Power (Add)
- This is for multifocal contacts. It can be a plus (+) sign with a number or, for certain brands, a description like "high" or "low".
Brand
- The brand is required for the prescription and specifies which kind of contacts you are allowed to buy.
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