If you are over 40 and have difficulty seeing close up, you probably have a common age-related condition called presbyopia which is when the eye’s natural lens loses the ability to focus on close objects. Presbyopia is a natural process as the eye ages and affects the majority of people from age 40 and upward. Individuals with presbyopia are often familiar with the need to hold reading materials such as newspapers an arm’s length away from their eyes in order to see clearly, yet reading glasses with bifocal or multifocal (progressive) lenses can help.
Fortunately for those who don’t like the look, feel or inconvenience of reading glasses, there is another option. Bifocal and multifocal lenses are also available in contact lenses in both soft and Rigid Gas Permeable (RGP) varieties.
Multifocal contact lenses give you added freedom over glasses and they allow you to be able to view any direction - up, down and to the sides - with similar vision. People wearing progressive lenses in glasses on the other hand have to look over their glasses if they want to view upwards or into the distance.
Our Phillipsburg, NJ Optometrist Will Explain The Difference Between Bifocal & Multifocal Lenses
Just as the name indicates, bifocal lenses are divided into two distinct segments for different vision powers, the first for distance vision and the second for near vision. This enables you to clearly switch your focus from near to far as needed, but your vision will not necessarily be clear in between. The term multifocal lenses can refer to any lenses with multiple powers including bifocals, trifocals or progressive lenses. Non-bifocal multifocal lenses have a range of powers that enable you to constantly adjust your focus to see clearly from up close to far and in between.
Multifocal contact lenses are generally designed in one of two ways, as either simultaneous vision lenses or alternating vision lenses.
Simultaneous vision lenses
The most popular version of multifocal contact lenses, simultaneous vision lenses present the distance and near vision zones of the lens at the same time. Typically after a short adjustment period your eyes learn to utilize the segment of the lens that they need to focus on the desired object and essentially ignore the other.
They come in two designs:
- Concentric ring design: In the most basic form these are bifocal lenses that are comprised of a central circular area of one power with a ring around of the alternate power, similar to a bulls-eye. In this design the power of the rings (either near or distance vision is interchangeable). For intermediate viewing (18-24 inches away) extra rings can be added to create a trifocal or multifocal lens. The width of each ring is variable depending on the power that is needed most and the edges of the rings can be blended for a smooth transition of focus, similar to progressive eyeglass lenses.
- Aspheric design: These multifocal lenses attempt to provide a natural vision experience by blending many lens powers across the surface and center of the lens. In this design both distance and near vision power are located in the central visual area and your eyes will adapt to focus on the area needed to view what you are looking at.
Translating or Alternating Vision lenses
Similar to bifocal eyeglass lenses, these contacts are divided into distinct areas or zones and your pupil will move to the desired zone depending on your vision needs. Typically the top of the lens, which is what you look through when looking straight ahead is for distance vision and the bottom area (what you look through when you look down) is for near vision. However, this can be reversed according to unique vision needs.
Since contact lenses sometimes move within your eye, translating lenses are held in place by a ballast which is an area that is thicker than the rest of the lens or by truncating or flattening the bottom to stay in line by the lower lid. These lenses are only available in rigid gas permeable lens material.
An Alternative Option to Multifocal Contact Lenses: Monovision
Monovision is another contact lens alternative for presbyopia particularly if you are having difficulty adapting to multifocal lenses. Monovision splits your distance and near vision between your eyes, using your dominant eye for distance vision and your non-dominant eye for near vision.
Typically you will use single vision lenses in each eye however sometimes the dominant eye will use a single vision lens while a multifocal lens will be used in the other eye for intermediate and near vision. This is called modified monovision. Your eye doctor will perform a test to determine which type of lens is best suited for each eye and optimal vision.
Are Contact Lenses Right for You?
If you have presbyopia, contact lenses may be a great option for you. Many people prefer the look and convenience of contact lenses over traditional reading glasses. Speak to our optometrist in Phillipsburg, NJ about the options available to you.
Types of multifocal contact lenses
Based on design, there are basically two types of multifocal contact lenses:
- Simultaneous vision lenses. With these lenses, both distance and near zones of the lens are in front of your pupil at the same time. Although this might sound unworkable, after a short period of time your visual system learns to use the power you need and ignore the other lens power(s), depending on what you are looking at. Simultaneous vision lenses are the most popular type of multifocal contact lens. They are nearly always soft lenses, and are available in two designs:
- Concentric ring designs - These are bifocal lenses with either the distance or near power in the center of the lens, with alternating rings of distance and near powers surrounding it.
- Aspheric designs - These are progressive-style multifocal lenses, with many powers blended across the lens surface. Some aspheric lenses have the distance power in the center of the lens; others have the near power in the center.
- Alternating vision (or translating) lenses. These are GP multifocal lenses that are designed like bifocal eyeglass lenses. The top part of the lens has the distance power, and the bottom part of the lens contains the near power. When you look straight ahead, your eye is looking through the distance part of the lens. When you look down, your lower lid holds the lens in place while your pupil moves (translates) into the near zone of the lens for reading.
Will multifocal contact lenses work for me?
In monovision, you wear a single vision contact lens on one eye for your distance vision and a single vision contact lens on the other eye that has a prescription for your near vision. In modified monovision, you wear a single vision "distance lens" on one eye and a multifocal contact lens on the other eye to help you see better up close.
To determine the best contact lenses for your vision needs when you reach "bifocal age," call our optometrist for a consultation near you.
Read about Ortho-K to see if you may be a good candidate for these gentle overnight cornea re-shaping contact lenses.
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