Astigmatism and
Toric Lenses - The Condition and the Solution
By Michael Wright
What is Astigmatism
Astigmatism is quite a common condition caused by
irregularities in the cornea or lens of the eye, and distorts
the image on the retina. Those having a slight blurred vision
are not even aware that they have astigmatism. In the case of
more severe astigmatism, everything is blurry at a distance,
and it becomes impossible to ignore the condition. People who
suffer from astigmatism can have their vision improved by the
usage of toric lenses.
Usually, astigmatism is a hereditary condition, where the shape
of the eye is irregular. The normal spherical shape of the
cornea, or the lens, of the eye is more oblong - football ball
like. Astigmatism may accompany Myopia (nearsightedness) or
Hyperopia (farsightedness). Astigmatism can usually be
corrected with toric contact lenses among other methods, such
as glasses and refractive surgery.
Types Of Astigmatism
There are basically two variations of astigmatism – regular astigmatism
and irregular astigmatism.
Regular astigmatism is usually easier to correct. In it, the meridians in
which the two different curves are, are located 180 degrees apart. In the
case of irregular astigmatism, which is more difficult to correct, the two
meridians may be more, or less, than 180 degrees apart, or there may be more
than two meridians. Correcting this is quite complicated and depends on the
extent of irregularity, and the cause behind it.
Toric lenses can easily correct regular astigmatism, whereas irregular
astigmatism, being more complicated and difficult to correct, requires
custom made contact lenses. Astigmatism,
whether slight or severe, should not be ignored, as it not only gives you a
blurred vision, it also gives you headaches and eyestrain.
Children too develop astigmatism and are either generally not aware, or do
not complain. Nevertheless, it makes their life quite difficult. It is best
that you have your child’s eyes
tested every year, and if diagnosed with astigmatism, can have this
condition corrected with toric contact lenses.
Curing Astigmatism - Toric Lenses For Astigmatism
Correction
The earlier belief that people with astigmatism could not wear contact
lenses, and only Rigid Gas Permeable (RGP) contact lenses could correct
astigmatism is no longer true. Soft
contact lenses that can correct astigmatism are called toric contact lenses,
and they can do an equally good job of correcting your, and your child’s,
astigmatic vision.
They have a special inbuilt correction that also has correction for either
nearsightedness, or farsightedness, depending on your condition. In the past
soft toric contact lenses were not
available in disposable, frequent replacement, multi-focal, or colored
varieties. Today, you have many options available to correct your
astigmatism with toric contact lenses, unless you
have an especially complicated prescription.
Soft toric contact lenses are made from the same materials regular
contact lenses, which are also known as spherical contact lenses, are made
from. To take care of astigmatism, and
either myopia or hyperopia, toric lenses are created to have two different
powers in them with curvatures at different angles.
The normal ‘spherical’ contact lenses have the same power all around, and so
it does not matter if the lens rotates in the eye. In the case of toric
contact lenses, due to the two
different powers, there is a need to keep the lens from rotating, to
maintain the best visual acuity. For this, they are ‘ballasted’ by making
them heavier at the bottom. This mechanism keeps the lens relatively stable,
providing you with crisp vision, when you look around or blink.
The fitting of the soft toric contact lenses will take more time and
expertise of your optometrist than for the normal regular contacts. Some eye
care practitioners may fit you with
high powered spherical soft lenses to correct your mild astigmatism. The
results will vary from person to person, and by a trial and error method. It
is best to opt for toric
contact lenses, even though the cost of fitting, and the cost of the lenses
themselves, will be more than the spherical lenses.
Types Of Toric Contact Lenses
When looking for toric contact lenses, you have a choice of color and
disposable lenses.
Toric contact lenses are available in many colors that change or enhance
your natural eye color. Most colored toric contact lenses are non-disposable
conventional contacts, and only some colors are available as disposables.
The four types of colored toric contact lenses are visibility tints,
enhancement tints, opaque color tints and light-filtering tints.
Visibility Tints – These are usually with a light blue or green tint. These
tints are added to a lens, just to help you see it better if you drop it, or
during insertion and removal. The
very light tint does not affect your natural eye color.
Enhancement Tints – These are translucent but solid tints that are a bit
darker than visibility tints. They do affect eye color, as they are meant to
enhance the existing color of your eyes, as implied by the name. They
intensify your eye color, and produce the best results for people who have
light colored eyes.
Opaque Color Tints - The deeper opaque tints dramatically change your
eye color. They best change your eye color especially if you have dark eyes.
The colors include hazel,
green, blue, violet, amethyst and gray.
Light Filtering Tints – The latest in color toric contact lenses are the
ones with light filtering tints. Specially designed for sports use, the
light filtering tints enhance
certain colors, by muting other colors. They enhance the vision of sportsmen
by making the ball stand out against the background, and allow them to see
the target more easily.
Disposable lenses were designed to be worn for a specific period and then to
be disposed of. They are more hygienic than traditional lenses as substances
that are found naturally in
your tears, like protein, calcium, and lipids, can build up on your lenses,
causing discomfort. The alternate to disposable lenses is to clean your
conventional toric lenses regularly.
If you are suffering from astigmatism, it is best you visit your optometrist
for a fitting of toric contact lenses – the best option available today.
About The Author: Michael Wright is a virtual authority on contact lenses.
He also writes articles about astigmatism and colored contacts. For more
free-reprint articles by Michael Wright please visit:
http://www.isnare.com/?s=author&a=Michael+Wright
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