What is plano in a spectacle presciption?

In a spectacle prescription, "plano" refers to a lens that has no refractive power, meaning it does not correct for nearsightedness (myopia) or farsightedness (hyperopia). It is typically denoted as "pl" or "0.00" in the prescription. Plano lenses are often used for individuals who do not require vision correction in one or both eyes or for cosmetic purposes in non-prescription glasses.