What Are Trifocal Lens?

With age, people may start to notice normal age-related loss of near vision, a condition called presbyopia. Even though this may feel frustrating or even scary, modern technology has developed trifocal lenses that help restore reading vision and give you a wider vision range. Trifocals are lenses that have three different powers in one lens, thus a lens has three fixed fields of focus (near/intermediate/distance). This eliminates the need to carry several pairs of eyeglasses.

Invention of Multifocal Lenses

• Benjamin Franklin first invented multifocal lenses for eyeglasses. These were the predecessors of trifocals lenses. Before that, people suffering from presbyopia needed two pairs of eyeglasses -- one for long-distance and the other for short distance. In the 1780s, Franklin glued together two lenses (a long-distance and a short distance lens), which he had cut in half. New bifocal lens, also known as the executive bifocal, was born. These first bifocals had a line across the entire width of the lens. The design of the lens further developed into fusing round segments for near vision into the long-distance lens.

From Bifocals to Trifocals

• As people age into their fifties, presbyopia grows to affect the intermediate vision. With the help of bifocals, a person can see clearly close and far, but their vision at arm's length can remain blurred. The blurring of the intermediate vision mostly affects reading. In the 1940s, the invention of trifocals solved this problem. Trifocals have a second lens segment above the near vision segment in a long distance lens, giving the lens three power zones. The intermediate segment usually has 50 percent more magnification than the near segment.

Modern Trifocal Lenses

• There are two main types of modern trifocal lens designs -- flat-top and executive style. The executive style has ribbon-shaped segments with lines throughout the width of the lens. Flat-top design has round segments without lines. The most popular is a flat-top design with a near and an intermediate segment, which is 28 mm wide. Today trifocal lens segments can be custom fitted into your eyeglasses according to your individual vision requirements.

Trifocal Contact Lenses

• Technology today has made it possible to develop a wide range of multifocal contact lenses. According to Lensesweb.com, the popularity of multifocal contact lenses rises every year. The advantage of trifocal contact lenses is that they allow you to see things in the near, intermediate and distance zones without any efforts. These are great for motorists, drivers and people who work at the computer. Executive contacts are the most popular ones. The placement of trifocal contact lenses in your eye is higher than other contact lenses so that the intermediate zone of the contact lens is on the pupil of the eye. In order to be able to have a clear near vision, trifocal contact lens wearers need to drop their eyes downward. This will make their eyes adapt to the near vision part of the contact lens.

Concerns of Using Trifocal Eyeglasses and Contacts

• One disadvantage of all trifocal lenses in eyeglasses or contact lenses is that they can make objects at your foot level look blurry unless you tilt your head down. This can be a safety concern especially for elderly users when stepping down or using stairs. After trying trifocal eyeglasses or contact lenses, most people find their advantages bigger than the disadvantages. Trifocals are quite easy to get used to and their wider field of view offers a great help for computer users suffering from presbyopia.