Glasses prescriptions often use abbreviations and numbers that can be confusing. A common term is “PL,” which is shorthand for a specific lens power value. Understanding what PL signifies is key to interpreting your prescription and confirming the required optical correction for your eyesight.
The Meaning and Placement of Plano (PL)
The abbreviation “PL” stands for Plano, derived from the Latin word planus, meaning “flat” or “level.” In an eyeglass prescription, Plano indicates zero correctional power (0.00 diopters) for a specific part of the lens. A lens designated Plano has no optical focusing power and is optically equivalent to a clear pane of glass.
This term most frequently appears in the SPH (Sphere) column. When PL is listed in the SPH column for one or both eyes, it means that eye does not require correction for nearsightedness (myopia) or farsightedness (hyperopia). It is normal for a prescription to show PL in one eye but a numerical power in the other, a condition known as anisometropia.
Plano may also appear in the CYL (Cylinder) column, though this space is often left blank or marked with 0.00. If PL is present in the CYL section, it confirms the eye does not require correction for astigmatism. It is possible to have PL in the SPH column but still have a CYL value, indicating that only astigmatism correction is necessary.
Interpreting Other Key Prescription Terms
To understand where Plano fits, it is helpful to know the other main columns on a prescription sheet. The first distinction is between the eyes, abbreviated as OD (Oculus Dexter or right eye) and OS (Oculus Sinister or left eye).
The SPH (Sphere) column details the lens power needed to correct for nearsightedness or farsightedness. A minus sign (-) denotes nearsightedness, while a plus sign (+) signifies farsightedness. This spherical power is uniform across the entire lens surface.
The CYL (Cylinder) and AXIS columns correct for astigmatism, a common vision issue caused by an irregularly shaped cornea or lens. The CYL value measures the magnitude of the correction needed. The AXIS is a number between 1 and 180 degrees that specifies the orientation of the cylindrical correction on the lens.