Used to specify the correction strength needed for eyeglasses or contact lenses.

Vision Correction

Positive dioptres for farsightedness; Negative for nearsightedness.

Positive and Negative

A small change in dioptres can significantly affect vision clarity.

In ancient times, dioptre was used for studying positions of celestial bodies.

Ancient dioptres measured angles, not the distance between stars.

It was also used in land surveying to measure angles on the horizontal plane.