Diopter: what is it?

Lilya Mayak
Lilya Mayak
January 27, 2015
Diopter: what is it?

In our century, when a huge number of people spend most of the day at the computer, eye problems have become very common. When a visually impaired person seeks an ophthalmologist for consultation, he will surely hear from him about such a concept as diopter, since it is this unit that measures optical power. We will tell you what diopters are in lenses and why they are needed.

Basic definition

If you ask the question "what is it - the diopter?", You first need to know that this term refers to the unit of measurement of the optical power of various systems in optics. One diopter corresponds to the optical power of the lens having a focal length of one meter.

It is important to know that the optical power of the lenses that collect the rays is called positive, and those that dissipate them are negative. Thus, with the help of this unit is expressed the optical power of glasses and lenses. By the way, read our articles on the topic What are glasses and How to use glasses.

Consequently, myopic people are suitable for lenses with a negative number of diopters, that is, scattering, and farsighted, on the contrary, lenses that have positive optical power, that is, collecting.