Convenience is a huge factor in disposables, not surprisingly.
Daily insertion and removal still requires cleaning, sterilizing
and regular placement of the lens. While many
contact lense
wearers establish a routine, others find the practice something
they would prefer to avoid. Disposables offer that option. Some are
designed to be worn once and then just tossed. Many types of
extended wear disposables can stay in overnight, or a week, or even
up to a month.
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Since those are inserted only once, they never need to be cleaned
or sterilized at all. You just clean your hands, insert them, then
throw them away after the wear period. No muss, no fuss. But, that
convenience comes at a price.
Cost is a factor to consider and it's not always negligible. While
prices vary over time, disposables are typically more expensive
over the long run. You pay for the convenience. But the daily costs
are lower, since the lens is intended to be used only for a short
period.
One way manufacturers can do that, of course, is to use different
materials and production methods. The result is a safe, comfortable
lens but one that may not provide the same optimally sharp vision
that another style can.
Still, many sports enthusiasts enjoy
disposable lenses thanks to their tight fit, which
results in them being very hard to knock loose. And if the quality
is good enough for them, it will probably be good enough for most
everyone.
Investigate your options in disposable
contact lenses and you may well find
one that is just right for you and your lifestyle.
Date Published: Mar 13, 2009 - 9:09 am
part 1:
Disposable contacts were first introduced in 1987. Since then they
have become one of the most popular options for
contact lense
wearers. They're comfortable, safe and come in a variety of
different types.
Disposables are designed to be worn and discarded either daily,
weekly, bi-weekly or monthly. But it's important to keep in mind a
distinction, that between the replacement schedule and the wear
schedule. Some are designed to be worn daily and discarded daily.
But some that are labeled dailies are removed daily, cleaned and
stored, then reused up to their intended lifetime. That lifetime
can be one week, two weeks, or even as long as a month. Make sure
you note which is which when you choose your lenses.
The more often you change your
prescription contact lenses the lower the odds of
health problems. Even the best of contacts reduce the amount of
oxygen that gets to the surface of the cornea. That ups the chances
of infection. Longer wear cycles also increase the odds of corneal
abrasion, conjunctivitis and other eye health issues.
However, changing lenses more frequently can increase the odds of
introducing other kinds of health problems. For example, some
preservative solutions can cause an allergic reaction to some
contact lens users. Wearing a pair of disposables continuously for
a week, then simply throwing them away, eliminates that
possibility. They come packaged in a sterile solution, so they
never need to be cleaned unless they're removed and re-inserted.
Date Published: Mar 11, 2009 - 9:17 am
Contemporary
contact lenses are comfortable, long-lasting (unless by
design, as in disposables) and very safe. Yet, there are some
risks and limitations in wearing them and knowing what those are
can help you choose the type that’s best for you. Of course, any
such decision should be made in consultation with your eye care
professional.
Since 1986 many have opted for Rigid Gas Permeable contact
lenses. Modern designs allow for up to five times more oxygen
diffusion through the plastic than those of the past. That
feature is important in minimizing the odds of corneal infection.
The less oxygen that makes it to the eye, the higher the odds of
an infection.
On the downside, RGP lenses are a little less flexible than other
types, making them less comfortable for some. But, they may be
better for correcting astigmatism as a result. They also can last
up to 2-3 years, which is longer than typical soft contact
lenses.
Hydrocurve III (Toric) Contact Lenses
Date Published: Mar 07, 2009 - 4:07 pm
Have you ever wondered if what you know about
contact lense is accurate? Consider the
following paragraphs and compare what you know to the latest info
on contact lense.
Modern contacts are manufactured to extremely high standards.
Millions wear them daily and for years without health problems or
even discomfort. Still, about 4% of all contact lens users
experience some type of health issue at some point. Risks of
wearing contact lenses, while very low, are not zero. Your odds can
be improved by proper use, though.
One overall issue is the fact that any contact lens will restrict
the amount of air that gets to the eye. That increases the odds of
infection, even when lenses are well sterilized. With the
popularity of 7 day or even 30-day continuous wear lenses, that
problem (while small) is larger than it was in the past.
Apart from infection, discomfort and blurred vision can occur when
a lens is worn for more than a few days. That irritation can occur
to the eyeball itself, and also to the lens and surrounding
tissues. One possible result is GPC (Giant Papillary
Conjunctivitis).
GPC produces itching and redness on the surrounding tissue, the
result of protein buildup on the surfaces of the lens. Swelling
occurs on the interior surface of the eyelids and can produce a
sticky discharge as well. When this occurs, you should discontinue
use until your eye care professional declares the lenses are safe
to wear again. Regular, careful lens care and proper use can reduce
the odds of any re-occurrence.
Corneal abrasions, while uncommon, are also far from unknown among
contact lens users. A small scratch on the clear tissue over the
pupil can happen when small particles of grit get between the lens
and the eye, usually as a result of poor cleaning or handling. But
it can occur even to the most careful, as airborne or finger-borne
material lands on the surface of the eyeball.
Knowledge can give you a real advantage. To make sure you're fully
informed about contact lense , keep reading.
Hopefully the information presented so far has been applicable. You
might also want to consider the following:
Small pieces of eyelash, cotton threads, airborne plant material
and much more can all wind up in the eye. In the absence of
contacts these things are normally washed away by the tears and
eyelid working together. Contacts can interfere with that process.
In many instances, antibiotics are called for since infection is
common under these circumstances.
Pollen and other material can also produce allergic reactions that
are sometimes amplified by contact lenses. The eyes become red and
irritated and excessive tearing can occur, leading to blurred
vision and discomfort. Sometimes the reaction is the result of
preservatives in the lens cleaning solution. It happens more often
with soft contact lenses. Treatments include removing the lens for
a time, changing solutions and using different storage methods.
The contact lenses themselves can cause problems if they change
shape. While rare, previously well-fitting contact lenses can be
affected by temperature and age, causing tears and oxygen to less
efficiently make it to the eye. This so-called Tight Lens Condition
can cause pain, redness and even swelling of the cornea. Correction
consists of remeasuring the eye and fitting new contacts after the
eyes have recovered.
The cornea itself can change shape, as can the whole eyeball. The
change is subtle, but with contact lenses the tolerances are small.
If corneal warpage (as it's called) does happen the result can be
discomfort and an increase in the odds of infection. The condition
is more common with gas permeable and hard lenses, which are less
flexible than soft contact lenses.
If this happens, healing can take weeks or months, during which
time contact lenses can't be worn. As the eye resumes its normal
shape, vision can change. More than one glasses prescription may be
required for optimal sight. In rare cases the astigmatism is
permanent.
In all cases, following the manufacturer's and
your eye care professional's guidance about
cleaning, insertion and removal, contact lens care and wear are
your best bet to avoiding problems.
Of course, it's impossible to put everything about contact lense
into just one article. But you can't deny that you've just added to
your understanding about contact lense, and that's time well
spent.
Sometimes it's tough to sort out all the details related to this
subject, but I'm positive you'll have no trouble making sense of
the information presented above.
Date Published: Mar 05, 2009 - 8:30 am
When the parts and process of vision work correctly, you see sharp,
colored entities out in the world. When things go wrong, the need
for a
contact lense
or glasses arises.
The human visual system is both simple and complex. Complex,
because there are so many parts that have to work together to make
sight possible. Simple, because those parts and the process can
really be explained without in-depth knowledge of anatomy and
biology.
An ordinary glass lens, such as a magnifying glass, focuses the
light that moves through it by bending the rays toward a focal
point. That's the bright spot you see when you hold one over a
newspaper, for example. Something similar happens when light enters
the eye through an opening called the pupil, behind a clear
protective portion called the cornea.
The pupil is surrounded by the iris, the colored portion of the
eye. The pupil can narrow or widen to regulate the amount of light
admitted, from as small as about 2mm to as much as approximately
8mm. The iris contains the muscles that change the diameter of the
opening. Just behind the pupil is the lens, the part that focuses
the light rays similar to the magnifying glass.
But there's an important difference between a magnifying glass and
the eye. The magnifying glass's focal point is fixed. The eye, by
contrast, contains muscles that help shape the lens and that
shaping process performs a number of important tasks. Most
importantly, it makes it possible for the focal point to
change.
A camera lens is a good analogy. Because the camera lens contains
multiple pieces of glass that can be moved by turning the barrel,
objects at different distances can be brought into focus on the
film. The muscles attached to the lens perform a similar function
in order to focus light onto the retina, which is like the
film.
Focused light rays strike the cells of the retina, the cones and
rods. The names come from the shapes of the cells. The cones - 7
million cells in the central part of the retina, called the macula
- are responsible for sharp, detailed vision and color vision. The
approximately 100 million rods around them help us see in dim light
and provide peripheral vision.
When those focused light rays hit the cells chemical reactions
occur that stimulate the optic nerve attached to the back of the
retina to produce electrical impulses. Those impulses are then
transmitted to the visual cortex, the part of the brain that
organizes them. Many parts of the brain cooperate to cause the mind
to conclude: 'Ah, a car.' But the visual cortex does the initial
heavy lifting.
Date Published: Mar 04, 2009 - 7:29 am