the book up close and the words appear blurred. Push the book farther
away, and the words snap back into sharp focus.
That's how most of us first recognize a condition that eye care
professionals call presbyopia, a name derived from Greek words meaning
"old eye." Eye fatigue or headaches when doing close work, such
as sewing, knitting or painting, are also common symptoms. Because
it is associated with aging, presbyopia is often met with a groan
-- and the realization that reading glasses or bifocals are inevitable.
What causes presbyopia?
As we age, body tissues normally lose their elasticity. As skin
ages, it becomes less elastic and we develop wrinkles. Similarly,
as the lenses in our eyes lose some of their elasticity, they lose
some of their ability to change focus for different distances. The
loss is gradual. Long before we become aware that seeing close up
is becoming more difficult, the lenses in our eyes have begun losing
their ability to flatten and thicken. Only when the loss of elasticity
impairs our vision to a noticeable degree do we recognize the change.
How does the loss of elasticity affect sight?
Our ability to "see" starts when light enters the eye through the
cornea. The shape of the cornea, lens, and eyeball help bend (refract)
light rays in such a manner that light is focused into a point precisely
on the retina.
The crystalline lens plays a key role in focusing light on the retina.
When we are young, the lens is flexible. With the help of tiny ciliary
muscles, it changes shape, or accommodates, for both near and distant
objects by bending or flattening out to help focus light rays. As
we age, the lens becomes stiffer. Changing shape becomes more difficult.
Not only does focusing on near objects become more difficult, the
eye also is unable to adjust as quickly to rapid changes in focus
on near and distant objects.
When does it occur?
The flexibility of the lens begins to decrease in youth. The age
at which presbyopia is first noticed varies, but it usually begins
to interfere with near vision in the early 40's. Presbyopia affects
everyone and there is no known prevention for it.
How is the problem diagnosed?
An accurate, thorough description of symptoms and a comprehensive
eye health examination, including a testing of the quality of your
near vision, are necessary to diagnose presbyopia.
How is presbyopia treated?
Usually, the treatment for presbyopia is prescription eyeglasses
to help the eye accommodate for close-up work. Prescription lenses
(reading glasses) help refract light rays more effectively to compensate
for the loss of near vision.
If you do not have other vision problems, such as nearsightedness
or astigmatism, you may only need glasses for reading or other tasks
done at a close range. If you have other refractive errors, such
as nearsightedness, bifocal or progressive addition lenses (in which
the power of the lens changes gradually towards the bottom to allow
reading, without the reading portion of the bifocal lens obviously
visible) are often prescribed.
Can I still wear contact lenses?
Yes, you have three options with contact lenses: Bifocal contact
lenses, monovision, and normal distance contact lenses with reading
spectacles. Generally, bifocal contact lenses are not as successful
as the normal "single vision" ones.
What lens option will work best for me?
Your eye care professional may ask a number of questions to help
determine the best avenue of treatment. You may be asked to describe
your usual lifestyle or daily activities and from this your practitioner
will be able to recommend a solution most suited to your needs.
For instance, if you are a librarian, your needs will be significantly
different from those of a truck driver.
- Optometry | Visual Acquity
| Myopia | Hypermetropia
| Astigmatism |
| Presbyopia | Cataract | Glaucoma|