Your prescription (RX) is a written authorization provide by your ophthalmologist (an MD) or optometrist (a doctor of optometry) to correct your vision with corrective lenses.
This is a prescription（Rx）.
What Are The Terms On Your Eyeglass Prescription?
O.D. stands for oculus dexter, meaning right eye.
O.S. stands for oculus sinister, meaning left eye.
SPH (or Sphere) indicates the strength of your lens, or how strong your lenses need to correct your nearsightedness or farsightedness.
CYL (or Cylinder) indicates the amount of lens power for astigmatism, it also tells the lens strength needed to fix astigmatism.
AXIS describes the degree and direction of your astigmatism.
ADD or NV This provides magnifying power for reading, progressive and bifocal lenses. You will have the same number for both eyes. ADD is only needed for magnifying power of reading, progressive and bifocal lenses.
PRISM A prism number indicates the amount of prismatic power, measured in diopters, needed to compensate for any alignment problems in your eyes.
BASE This will either appear in a column of its own or be included in the prism column. This column indicates the direction of a prism by noting the relative position of its thickest edge.
If the base is directed upwards, the column will read "BU," "base up" or simply "up." If the base is directed down, it will read "BD," "base down" or "down." If the base is directed toward the wearer's nose, the column will read "BI," "base in" or "in." If the base points away from the wearer's nose and toward the ear, the column will read "BO," "base out" or "out."