How Do Bifocal Contact Lenses Work

Bifocal contact lenses are designed to provide clear vision to both distance and near for people experiencing an age-related decline in eyesight (presbyopia) and other refractive errors.

Presbyopia, also known as the aging eye condition, is a natural and progressive decline in ability to focus clearly on objects from up close. People over the age of 35 are at risk of developing it, but everyone is affected to some degree from a certain point in their lives. A high percentage of bifocal eyeglasses & bifocal contact lenses use is because of presbyopia.

The difference between multifocal and bifocal contact lenses

Multifocal contact lenses include all lenses providing vision correction to more than one field of vision, including bifocal contact lenses. Similar to prescription glasses terminology, when people refer to multifocal contact lenses they actually mean progressive contact lenses that have a range of optical powers in each lens, providing clear vision to all distances. Bifocal contact lenses provide vision correction to near and distance fields of vision.

Bifocal contact lenses materials

Bifocal contact lenses can differ in material, and there are two main types:

1. Rigid contact lenses (RGP or GP): Crafted out of durable plastic incorporated with silicone. They tend to provide slightly sharper vision in comparison to soft contact lenses, are more durable than soft lenses and under proper care can last for several years.
2. Soft contact lenses: Usually made out of silicone hydrogel or other hydrogels. They are the most popular type of contact lens in the United States, allowing more oxygen flow to the eyes. Unlike rigid contacts, they feel comfortable right away or after not wearing them for a while.
3. Hybrid contact lenses: These feature a plastic center and soft peripherals.

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Different bifocal contact lenses designs

There are two group of bifocal contact lenses designs:

1. ‘Alternating vision’ contact lenses

Also known as translating bifocals, these bifocal contact lenses work similarly to bifocal glasses. There are two distinct optical powers (near & distance) that are separated by a visible line. You look through the upper segment for distance correction and through the lower segment for near correction.

2. ‘Simultaneous vision’ lenses

Unlike alternating vision contact lenses, with simultaneous vision bifocal contact lenses, you look through both optical powers, near and distance, at the same time. The brain learns to select the correct power depending on where you’re trying to look. Simultaneous vision bifocal contact lenses have two types of designs: Concentric ring and aspheric.

Concentring ring bifocal contact lenses have a prescription in the center of the lens and rings of different optical powers surrounding it. At least two rings are usually within your pupil area. Soft bifocal contact lenses feature the near optical power in the center and rigid contact lenses feature the distance power in the center of the lens.

Aspheric contact lenses work more like progressive eyeglass lenses. The different optical powers are blended across the lens. In glasses with progressive lenses, you only look through one correction “zone”. With simultaneous vision contact lenses, your eyes see through two correction “zones” or more.

Bifocal Contact Lenses or Bifocal Glasses

The choice between bifocal glasses and bifocal contact lenses comes down to comfort and necessity. Contact lenses are higher maintenance than glasses but are often the popular choice for people with an active lifestyle who don’t want to worry about their frames falling or breaking. Others choose contact lenses because they prefer a glasses-less look. There are also some optical advantages to wearing contact lenses such as better peripheral vision.

One thing worth noting is that bifocal contact lenses don’t provide as sharp a vision as bifocal glasses, so you’ll probably still need to keep a pair of reading glasses at hand when looking at a small print.

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