Bifocal Contact Lenses?
Surprise! There are bifocal contact lenses. In fact, trifocal and progressive contact lenses are also available.
Who is a candidate for such lenses? These contact lenses are great for people who normally wear regular bifocal or progressive glasses. Also, people who are over 40 may get presbyopia, a natural condition of the eye when the lens of the eye becomes less flexible. Presbyopia is not farsightedness, but it seems like that for reading. For people with presbyopia, these lenses are perfect.
Two categories of bifocal contact lenses exist: translating and simultaneous. The translating lens, also called segmented or alternating lens, changes power by whether you are looking upwards or downwards. The distance power is usually in the top half and the near power is in the lower half.
Simultaneous lenses are the most popular, because they allow people to see both far and near at the same time. There are two types of simultaneous bifocal lenses: aspheric and concentric. Traditional contact lenses are spherically designed if they do not correct for astigmatism. Aspheric lenses vary the curvatures across the surface, changing from the center of the lens to the edges. Their gradient allows for a slightly different focus depending upon how far from the center of the lens the light enters. Interestingly enough, aspheric lenses seem to create a clearer vision for most people than normal spherical types.
Concentric lenses are amusing in concept, yet they really work. In the center of the lens (for GP bifocals), you would have your prescription for far away, but then not far from that, in a concentric circle-like way, the lens curves for near distance, then a little further from the center, it goes back to far, then later back to near. There are usually at least two concentric rings within your pupil area, even though your pupil will change size according to light conditions. There are a number of different types, including ones that differ for your dominant eye versus your nondominant one.
The most difficult part of prescribing bifocal contact lenses is that each lens is customized for each patient and for each eye. Pupil sizes can vary. Depending upon the type of lenses desired, they may be silicone hydrogel, soft, or gas permeable (GP) lens materials.
If you need contact lenses, come on over to Swan Family Optometry for a contact lens exam. Once we know your situation and needs, we can fit you with the contacts that will help you more clearly see the world. We are your local, friendly neighborly optometrist in Fair Oaks, CA.