When reviewing an eyeglass prescription, the abbreviation “PL” frequently causes uncertainty. This notation holds a specific meaning regarding the amount of vision correction required for that particular eye. Understanding what “PL” signifies is the first step toward comprehending the function of your new corrective lenses.
Defining Plano: What PL Means on Your Prescription
The abbreviation “PL” stands for “Plano,” which is a term derived from the Latin word for “flat” or “level.” In the context of optics, Plano means zero refractive power, which is the equivalent of 0.00 diopters of correction. This designation indicates that the eye does not require any lens power to correct for common refractive errors like nearsightedness (myopia) or farsightedness (hyperopia).
You will most commonly find “PL” listed in the SPH (Sphere) column of your prescription, which dictates the overall lens power for distance or reading correction. Seeing “PL” in the SPH column confirms that your distance vision is considered neutral in terms of spherical error. A lens with a Plano value will not change how light is focused onto the retina.
Understanding Zero Power: When and Why PL is Used
While “PL” in the SPH column suggests the absence of nearsightedness or farsightedness, it does not mean the eye requires no correction at all. A frequent scenario involves a mixed prescription where a patient has “PL” under SPH but still has values listed in the CYL (Cylinder) and AXIS columns. This indicates that while the eye is not spherically deficient, it requires correction for astigmatism, which is caused by an irregularly shaped cornea or lens. The lens will still be custom-ground to correct the curvature-related blur.
Another common application for Plano power occurs with presbyopia, a condition that necessitates reading glasses. In these cases, the eye might have “PL” in the SPH column for distance vision, but a positive number will appear in the ADD (Addition) column. This prescription structure means the person has clear distance vision but needs added magnifying power for close-up tasks like reading a book or a smartphone screen. Occasionally, “PL” may appear for one eye in cases of anisometropia, where one eye requires significant correction while the other eye has near-perfect vision.
Practical Impact of PL on Eyeglasses
A Plano value has direct effects on the physical construction of the resulting eyeglasses. Since the lens has zero optical power, it is inherently flatter and thinner at the center than a lens with a significant corrective power. This thin profile is maintained regardless of the material used, offering a more aesthetically pleasing option for the wearer. Lenses with “PL” values are often less complex to manufacture than highly corrective lenses, which can translate to a lower cost for the final product.
Even with a Plano prescription, the lens is not simply a piece of flat glass, as it still serves several functions. It can be made with protective features, such as impact-resistant material for safety glasses or specialized coatings. Many people choose to add features like anti-reflective coating, UV protection, or blue-light filtering to their Plano lenses for comfort and eye health. If the entire prescription—SPH, CYL, and ADD—is Plano, the resulting product is a non-prescription lens, used for style or protection.