What is a multifocal
lens?
A multifocal lens is
a lens that contains two or more different powers or corrections. The
most common multifocal lenses are bifocals (two powers) and trifocals
(three powers). Quadrafocals, which are four different powers in one
lens, are prescribed for special purposes. Another type of multifocal
lens, the progressive additional lens, is designed to provide clear
vision from far to reading distance without break or interruption.
They contain no dividing lines between the different viewing
sections.
Why are multifocal lenses
prescribed?
Some individuals
require two or more different lens corrections for effective seeing
at different distances. Combining the two or more corrections needed
in one pair of lenses is a way to meet the specific visual needs of
each individual.
Do persons of all ages wear
multifocal lenses?
Yes. However, they
are most often first prescribed for persons between the ages of 40
and 45. Usually, at this time, there is a noticeable decline in the
eye's focusing ability. Known as presbyopia, this condition affects
the clarity of vision at reading distance. Since reading glasses,
while being worn, will cause distance vision to blur, multifocal
lenses are often prescribed to permit clear vision for reading as
well as other distances.
It is not unusual for
children to need bifocals. Sometimes bifocals are prescribed to
improve a child's near vision skills which affect reading and
writing, while at the same time, providing clear distance
vision.
Why are bifocals
prescribed?
Bifocals, or lenses
that combine two different powers, are prescribed to aid both near
and far vision in one pair of lenses. Usually the lower part of the
lens is to help see clearly at close distances and the upper part is
to aid focusing at far distances.
Why are trifocals
prescribed?
Trifocals, or lenses
that combine three different powers, are prescribed to aid not only
close and distance vision, but, "in between" distances too. Like
bifocals, the top part of the lens is usually for distance vision and
the bottom part is for reading. An additional correction in the
center of the lens is for mid-distance activities, like reaching for
an object on a store shelf, playing piano or card playing.
What are some suggestions for
wearing multifocal lenses?
- Don't look at
your feet when walking;
- Hold reading
material closer to your body and lower your eyes so that you are
reading out of the lowest part of the lens;
- Lower your eyes,
not your head, when wearing multifocal lenses;
- Fold the
newspaper in half or quarters and move it, rather than your head,
to read comfortably;
- Wear the lenses
continuously for the first week or two, until you are accustomed
to them, even though you may not need them for all tasks;
and
Make sure that
eyeglass frames are always adjusted for your face so that the lenses
are properly positioned.