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Presbyopia
The lens inside the eye is a marvelous structure. It actually
changes its shape when we attempt to see objects close to
us. When we focus up close, the lens becomes fatter, and when
we gaze into the distance, the lens becomes thinner.
This system works beautifully until we get close to forty
or shortly thereafter. Gradually the lens loses its ability
to focus (accommodation) and blurred vision for near objects
is the result. A slowness in changing focus from near to far
may also be noticed. This loss of accommodation is called
presbyopia. which is derived from presby@ meaning old and
opia@ meaning vision. In fact, this is the most predictable,
regular, routine age change in the whole human body. Nearsighted
patients in this age group may take off their glasses to see
up close, and this is one of the advantages to myopia (nearsightedness).
The chief symptom of presbyopia is difficulty In reading.
This may be aggravated by reading small print or reading in
dim light. Holding the reading matter farther away relieves
the strain temporarily, but our arms quickly get too short
for comfortable reading.
No treatment, including diet and exercise, can slow down the
progression of presbyopia. The best way to correct for presbyopia
is with lenses of the proper power to bring things into focus.
This can be done in many ways:
- READING GLASSES - These work
very well and have the advantage of giving us a full field
of vision. When looking into the distance, however, everything
appears blurry, necessitating their removal for better
distance vision.
- HALF GLASSES - These are
the ones Benjamin Franklin made famous. They also provide
good near vision, and if the patient has good distance
vision unaided by glasses, clear distance vision is obtained
by simply looking over the top of the half glasses. Some
patients wear these with a chain around their necks.
- BIFOCALS - These are probably
the most versatile solution. Good distance vision is obtained
through the top part, while clear reading vision is obtained
through the bottom part. Curbs, stair steps and objects
in our path may be blurred through the bifocal, so some
adjustment is necessary when first getting used to them.
Many different styles, including the no line@ bifocals,
are available.
- CONTACT LENSES - This can
be tricky, but many people find wearing one contact for
near and one for far vision is preferable to the other
forms of treating presbyopia.
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