What are varifocal lenses?
These are multifocal lenses that correct vision at different working distances, from reading distance to far distance. Unlike bifocals, they have a gradual change in prescription and don't have visible lines that separate the segments, so they look just the same as single vision lenses.
The distance vision part of the lens is usually in front of the pupil, with the near vision part in the lower section of the lenses. If you've been wearing single vision lenses, it might take some time to adjust to wearing them.