Single Vision Lenses
Single vision lenses are the cheapest and most common type of eyeglass lenses. They have the largest field of vision because they only correct vision at one specific distance (either far or near).
If you are nearsighted, farsighted, or have astigmatism, you’ll most likely be prescribed single vision lenses.
Bifocal lenses are multifocal, meaning they have two different “powers” in them. These different sections of the lens correct distance vision and near vision.
Bifocal lenses are prescribed for people with multiple vision problems.
Trifocal lenses are similar to bifocals. But they have an additional power to correct intermediate vision. The intermediate portion may be used to view a computer screen, for example.
The main shortcoming of bifocals and trifocals is that they have a distinct line between each field of vision. This makes the sections of the lens produce drastically different vision. Most people get used to this and don’t have an issue. But this drawback has led to the development of more advanced lenses, such as progressives.
Progressive lenses work for anyone who needs bifocals or trifocals. They provide the same correction for near, intermediate, and distance vision. They do this without the lines between each section.
Many people prefer these lenses because the transition between fields of vision is smoother.