1. A unit of measurement of the optical power of a lens or curved mirror, equal to the reciprocal of the focal length in meters.
Usage: Plural of diopter; Used in optometry and ophthalmology; Abbreviated as D

Examples

• The prescription calls for lenses with a power of +2.5 diopters.
• Her nearsightedness requires correction of -3 diopters in each eye.
• The eye doctor measured the diopters needed for her new glasses.
• A lens with 1 diopter has a focal length of 1 meter.
• The stronger the diopters, the more the lens bends light rays.