Is the unit of meassurement of a len's refractive power?

The unit of measurement for a lens's refractive power is the diopter (D). Refractive power is defined as the inverse of the focal length of the lens in meters; thus, a lens with a focal length of 1 meter has a refractive power of 1 diopter. Positive values indicate converging (convex) lenses, while negative values indicate diverging (concave) lenses.