Glossary of Eye Definitions and Glasses Terms

Want to discover all things eyewear? Find out more about your eyeglasses and sunglasses, word by word.



A diopter is a unit of measure that refers to the optical power of a lens, describing the distance at which an object is brought into focus when looking through the center of the lens. A positive diopter glasses prescription indicates the degree of correction needed for treating farsightedness while negative diopters indicate the degree of optical power necessary for correcting myopia.

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