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.
The Difference Between Bifocal and 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.
Are Contact Lenses Right for You? Ask Our Annapolis Eye Doctor
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 Annapolis eye doctor about the options available to you.