Contact Lenses:
Contacts for Presbyopia
As baby boomers reach middle age, the question looms large: How to
avoid either of two telltale signs of aging -- bifocals or reading
glasses?
Boomers
have three contact lens options for correcting the close-up blurred
vision that typically begins in middle age; a condition referred to as
presbyopia. (One of the three options still calls for reading glasses,
but they can be used discreetly.)
The three
options are:
-
Bifocal contact lenses
-
Monovision
-
Contact lenses for distance vision with supplementary reading
glasses slipped over the contacts for close work
Bifocal
contact lenses
One of the two main categories of bifocal contact lenses may be
suitable for you:
Simultaneous vision
With simultaneous vision bifocals, you look through both the reading
and distance portions of the lenses all the time. This means that
whenever you look at an object, you see two images of it. One will be
clear (from the portion of the lens most matched to the distance at
which you are observing). The other will be blurred (from the other
portion of the lens). Your brain learns to ignore the blurred image so
that you see the other clear image.
Translating
Translating bifocals are similar in concept to bifocal eyeglass
lenses. They have a thicker lower edge, which, when you look down to
read, rests on the lower lid. As your eye turns downward to read, it
looks through the reading portion in the lower part of the lens. In
fact, even though they "translate," a portion of vision through this
type of bifocal is of the simultaneous type.
If you
wear bifocal contact lenses, they will normally perform optimally in
bright conditions. Because bifocal lenses divide the light into two
images, each of which will use about half of the available light, you
may find that, in dimly lit conditions, seeing is more difficult with
bifocal contacts. Driving at night may present more difficulty, for
example.
Monovision
Monovision is an option in which one eye is fitted with a lens for
seeing things at a distance and the other eye is fitted for seeing
close-up. After a period of adjustment, the brain switches to the eye
that is giving the clearest image at the time.
While
many people successfully use monovision, others find adapting
difficult. Mildly blurred vision, dizziness, headaches and a feeling
of slight imbalance may last for a few minutes or for several weeks as
you adapt. Generally, the longer these symptoms last, the more
unlikely it is that you will adapt successfully. Approximately
two-thirds of patients eventually adapt to a monovision correction.
Adjusting to demanding conditions
If you are new to monovision you may benefit from avoiding visually
demanding situations at first, and instead to wear their new lenses
only in familiar situations. For example, it may be better to be a
passenger, rather than a driver, in a car. In fact, you should only
drive with monovision correction if you can pass your driver's license
eye examination while wearing it.
Coping
in special situations
Some people are uncomfortable in situations with low illumination,
such as night driving. If that is your concern, ask us about
prescribing an additional lens to correct both eyes for distance for
those times when sharp distance vision is required. An alternative is
a pair of glasses with additional power in the reading eye so that the
combined power of your contacts and the spectacles match your distance
prescription.
If you
require very sharp near vision, you might want to ask about an
additional lens to correct both eyes for close-up work. Or, to
occasionally have the clearest vision for critical tasks, you may want
to request supplemental glasses to wear over your monovision
correction, converting the distance eye to a reading prescription so
that you can use both eyes at near distance.
Contacts for
distance; reading glasses for near vision
The final option for correcting presbyopia is this: Wear contact
lenses for distance, then slip some reading glasses over them for
close-up work. Perhaps not the perfect answer, this option enables you
to avoid the dreaded bifocal glasses. And that can still be a definite
plus.
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