Dioptre is a unit of measurement used in optics to quantify the power of corrective lenses or the refractive error of the eye. However, there are several other terms or synonyms used to describe the same concept, such as refractive power, lens power, focal strength, or optical power. These terms are often used interchangeably in optometry, ophthalmology, and vision science to describe the degree of nearsightedness, farsightedness, or astigmatism of a person's eyes or the strength of their glasses or contact lenses. Moreover, dioptre is also closely related to other optical concepts like focal length, magnification, or vergence that are used to describe the behavior of light and lenses.