Called single vision, these lenses comprise of only one correction for a given distance: for myopia, for hypermetropia, for presbyopia and/or the astigmatism. They are known as simple since the optical power is the same for all of the lens.
Bifocal lenses
Bifocal lenses are intended for a person who needs two corrections, one for distance and for near vision, the top part of the lens corrects distance vision and the lower segment corrects near vision.
Progressive or Varifocal lenses
Progressive or varifocal lenses do not have any visible lines so they are therefore more pleasing from an aesthetic point of view. The power gradually changes from the top to the bottom of the lens. It is a more functional lens because the person wearing this type of lens has “continuous” vision. It makes it possible to see all objects located at variable distances whereas a bifocal lens only allows clear vision at two distances.
