How Do Multifocal Contacts Work? [ view all articles ]
With an ever growing aging population, there is an increased need to properly accommodate our presbyopic patients. Advances in contact lenses have made it easier and easier to not only keep these patients happy, but returning to our office. Are you aware of the technology behind the multifocal contact lens designs available?
The Right Contact Team has outlined a brief summary of the presbyopic lens designs that manufacturers are using. After reviewing, contact your favorite manufacturer/distributor and see what lenses they have to offer.
Concentric Multifocal (also known as Lenticulated or Annular)
Lens Type: Soft Lenses, Gas Permeable Lenses
This design has concentric rings of power to accommodate different focal lengths. A bulls eye pattern enables alternating zones of strength from near to far. When a similar design is given in both eyes, depth perception is preserved as the patient is truly binocular. The arrangement is generally near center and distance periphery, but modifications of the design are commonly used. Alternating distance for near or modified monovision are some of these tactics.
Simultaneous Multifocal (also known as Aspheric or Progressive Multifocal)
Lens Type: Soft Lenses, Gas Permeable Lenses, Hybrid Lenses
This design has both the distance and near vision portion of the lens in front of the pupil at the same time. This design requires the users eyes to ignore near objects when viewing distance objects, and to ignore distant object when focusing near. Pupil size is a big factor when considering these lenses.
Alternating Multifocal (also known as Translating / Bifocal / Trifocal)
Lens Type: Gas Permeable
This design has distinct zones in the lens for distance and near vision. When the user looks straight ahead they are using the distance portion of the lens. When looking down, correct lid interaction allows for near vision through the inferior portion of the lens.
The near segment can be designed in a half-moon, crescent, or annular shape. Stabilization techniques use prism ballasting or truncation.