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THE PRESBYOPIC POPULATION
Presbyopia is the loss of the ability to focus on close objects. A
natural occurrence that starts around age ten and affects nearly
everybody by the age of 40, presbyopia usually makes reading and close-up
work more difficult. Presbyopia is an entirely natural and normal
phenomenon, affecting almost 90 million people. Each year, an estimated
four million more people become presbyopic, making this group the
swiftest growing demographic segment requiring vision correction. While
presbyopia is impossible to prevent and won't go away - our
eyes will never learn to accommodate again - there are many simple and
effective ways to deal with it.
ARE YOU A PRESBYOPE?
A visit to an eyecare professional is the only way to be absolutely
sure of any necessary vision correction, but there are preliminary signs
that may indicate that presbyopia has set in. Headaches and blurred close
vision; and tearing, stinging or a gritty feel to the eyes, can be
symptoms of presbyopia. Other symptoms include a need for more light
to see clearly, and of course, the dreaded need for "longer arms" in order
to hold reading materials further and further away so that the eyes
can focus clearly.
HOW CAN PRESBYOPIA BE CORRECTED?
Reading glasses and bifocal spectacles --
The vast majority of presbyopes
wear some type of spectacles, usually bifocals, which combine both
distance and near vision correction in each lens, or reading glasses,
which simply correct near vision. Bifocal spectacles are often
recognizable by the segmented appearance of the lenses--"granny glasses".
Many individuals are reluctant to wear bifocal spectacles; they see
these glasses as a symbol of growing old.
Some presbyopes have had success wearing single vision contact lenses
with reading glasses only when necessary (without removing the contact
lenses). While this does not solve the problem for people who want
to be entirely free of glasses, it is a simple alternative that can save
time and money. In addition, there is no real period of adaptation.
Segmented Contact Lenses providing "Alternating Vision"--
The design
of segmented contact lenses is similar to that of bifocal spectacles,
but segmented lenses actually work differently. The top portion of a
segmented lens is for distance vision, the bottom for near, or reading,
vision. Look straight ahead, and the distance portion of the lens will
be in use; then look down to read, and the lens will bring the near vision
segment into the line of sight. As a result, this type of lens provides
alternating vision.
Certain design features help position the segmented lens on the eye.
For one, the lens may have a flat bottom edge to allow the lower eyelid
to assist in positioning; or it may be weighted on the bottom to prevent
rotation. Because lens position is critical, the fitting of segmented
lenses requires skill and patience. Several visits to a practitioner
may be required in order to get this perfect.
Bifocal contact lenses are available as both soft and
Rigid Gas Permeable
lenses (RGP's).
Simultaneous Vision Contact Lenses --
Simultaneous vision contact lenses
allow both distant and near objects to be in focus at the same time.
The design places both near and distance vision correction in concentric
rings --instead of top/bottom-- on the lens. A simultaneous vision
lens resembles a bull's-eye with its concentric circles, with each of the
circles providing different aspects of the vision correction. Some
may have a single ring while others have numerous, depending on the
individual prescription. When the brain receives the in-focus and
out-of-focus images simultaneously, it is able to select the desired
image
Related lens types include aspheric, in which the lens power changes
gradually, from the center to the edge of the lens, and diffractive,
which uses a series of grooves, cut into the back surface of the lens,
to provide near vision correction.
Monovision Contact Lenses --
An alternative to bifocal lenses, monovision
contacts correct one eye for distance vision and the other eye for
near vision. Today, more than 30 years since its invention, monovision still
has an extremely high success rate, yet only a small percentage of
presbyopes use this method. monovision offers the advantages of simpler
fitting and less expensive lenses, but some patients don't like the
loss of binocular vision that it causes. (Binocular vision is the ability
to use both eyes to see objects in three dimensions.)
Monovision usually requires a longer period of adaptation. Because depth
perception is altered with monovision, additional correction may be
needed for driving and operating heavy equipment. Under these
circumstances, driving glasses to correct the reading eye for distance
and improve binocular vision are recommended. Similarly, some wearers
may require an additional near vision correction in the distance eye to
allow prolonged or concentrated reading.
A variant of monovision, modified monovision, puts a bifocal contact
lens in one eye and a single-vision contact lens in the other eye. This
can give binocular vision for driving, while still permitting near vision
for reading.
THE ADJUSTMENT PERIOD
VISION CORRECTION OPTIONS AND THE EYECARE PROFESSIONAL
GETTING MORE INFORMATION ON PRESBYOPIA
In addition to consulting with your eyecare professional, you can get
information directly from the contact lens manufacturers as well as
from the professional associations for vision specialists. The Contact Lens
Council's website has
links to these organizations' sites, as well
as other useful sites.
GLAUCOMA CHECKS
Glaucoma is one of the leading causes of blindness in the U.S. It most
often occurs in people over age 40. The Contact Lens Council, along
with its advisory members, recommends annual eye examinations for people
at risk for glaucoma. Depending on your specific history, your doctor
may recommend more frequent exams. Glaucoma cannot be prevented, nor can
vision lost to glaucoma be restored. If, however, an annual examination
routine is followed, glaucoma can be controlled, as long as it is
diagnosed early.
People at high risk for developing glaucoma include those with a family
history of glaucoma, African Americans, the very nearsighted, and
diabetics.
Glaucoma is an eye disease in which the internal pressure in your eyes
becomes elevated due to clogged or blocked fluid channels. The nerve
fibers in the optic nerve are damaged resulting in vision loss.
Scientists are unsure as to why the passages become blocked.
Symptoms of glaucoma may include blurred vision or a gradual loss of
peripheral vision. The most common type of glaucoma, however, is asymptomatic, painless and
gradual, and must be detected by an eyecare professional.
A glaucoma check can be part of an optometric exam and will include
a tonometry test to measure the pressure in your eyes; an optical
examination that looks inside your eyes and at the optic nerves; and
a visual test to check for changes in central and peripheral vision.
The treatment for glaucoma normally includes eye drops and medicines
as prescribed by your doctor to lower the pressure in your eyes. In some
cases, laser treatment or surgery may be required to reduce pressure.
There are several options available to correct presbyopia, below:
The adjustment period can vary widely depending on the type of lens,
the patient's motivation and visual needs, and the fitting schedule. Some
simultaneous vision lenses require two weeks of continuous wearing
before the patient adapts to the lens, while other types of lenses may be
accommodated more quickly. The key to any adjustment period is ongoing
consultation with your eyecare professional.
As the "baby boomer" generation matures and enters the presbyopic years,
more and more eye doctors are correcting patients' vision with contact
lenses. The flexibility and convenience that contacts provide are leading
more and more people to contacts as science provides more options in
contact lens wear, particularly for presbyopes. Because there are so
many options, it is important to discuss the matter fully with an eyecare
professional. In helping a patient reach a decision, an eyecare
professional will consider the overall vision problems, the health
of a patient's eyes, and his specific visual needs and motivations. An eyecare
professional --either an optometrist or an ophthalmologist-- is best
suited to help evaluate vision correction options.