Multifocal lenses have multiple uses, so that you can see objects at varying distances using different lens corrections. A bifocal offers two different viewing fields (near and far). Progressives and trifocals offer three different viewing fields (near, arms-length, and far). Bifocals and trifocals have visible lines that separate the different areas of the lens. A progressive lens is a trifocal lens without lines; the top portion of the lens if for viewing distance objects, the middle section is for objects at arm’s length, and the bottom section is for reading.
There are three basic types of multifocal lenses:
Bifocals: provide two vision zones separated by a visible line. The bottom segment (often “half-moon” in shape) corrects for near or reading distances while the remainder of the lens corrects for distance vision.
Trifocals: offer three vision zones separated by visible lines. The upper area is for distance vision, the middle segment provides intermediate vision for distances between 2 and 7 feet, and the bottom segment holds the reading prescription.
Progressives: also referred to as “no-line bifocals”. These lenses are similar to trifocals in that they have 3 different prescription areas for near, intermediate, and distance vision. Progressives differ from bifocals and trifocals in that the different zones are not separated by visible lines, but rather offer a natural, “progressive”, transition between the different powers on the lens. This eliminates the problem of “image jump” associated with lined multifocals and presents a more attractive appearance.
Your eye doctor will discuss the benefits of these choices with you during your eye exam. However, you should make this decision based on your own lifestyle. Multifocal lenses are convenient because you don’t need to remove or change eyeglasses in order to read.
Some people prefer progressive lenses because they do not like other people to see the line
Getting accustomed to this kind of lens can be difficult, and you must have proper instruction by an eyecare professional. For example, the way to use multifocal lenses is to look down with your eyes, not with your head.
Nowadays, multifocal wearers have lots of options. They include special glasses for computers and other tasks that take place at the intermediate range, as well as lenses for reading distance and special combinations for unique work situations. You should ask you eye doctor which lens option is right for you