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The U.S. FDA describes a disposable contact lens
as a lens to be worn once and then discarded. There is no provision
for the
contact lens to be worn again after the specified time period.
The wearing period may be as short as a day or as long as a month.
The concept of disposable contact lenses and their introduction
in the later part of the 80’s was a path breaking one. Earlier
the contact lenses were used through the years until the lenses
were either lost or damaged or became intolerable. After these ‘marathon’ contact
lenses came the yearly replacement lenses as an improvement and
once the benefits of these were noticed, the next stage was the
development of lenses with shorter replacement intervals i.e.
frequent or planned replacement or disposable lenses.
Extended wear vs. Disposable lenses
Hydrogel contact lenses for daily wear gained popularity but
the associated complications of bacterial keratitis also began
to appear. Pseudonomas and other bacteria formed a barrier against
disinfecting solutions. Also many patients did not care for their
contact lenses properly. So the only way to remove these variables
from the contact lens use was to develop the extended wear contact
lens with the certainty that they would be a safer option due
to less exposure to handling and care solutions in addition to
being more convenient.
However, reports of microbial keratitis began to appear and many
specialists began to advise against extended wear use. Most doctors
believed that the perfect lenses were the ones which were to be
used once and then discarded. But the production of these would
fall short of demand and would be unaffordable, so the best option
was the idea of disposable or frequent wear contact lenses
Complications Associated with Extended wear disposable lenses
Though with the introduction of disposable contact lenses for
extended wear was approved in 1987 and practitioners thought that
it heralded great improvement in contact lens safety, this was
not absolutely true as there were still reports of keratitis.
Studies revealed that the rate was higher for disposable extended
wear contact lenses than for conventional extended wear lenses.
So, practitioners advised against them.
Though they were still prescribed, it was advised that the patients
wear disposable lenses on a daily basis and replace them at 2
to 8 week intervals. There were more peripheral ulcers or infiltrates
with disposable extended wear contact lenses also known as contact
lens peripheral ulcer. A variety of contact lens related complications
can interfere with the ability of individuals to continue using
these types of contact lenses.
Case for Disposable Lenses
When viewed broadly, the spectrum of contact lens related problems
including subjective and objective complications; it is found
that the overall incidence of contact lens related problems was
significantly lower for disposable extended wear lenses than for
conventional extended wear lenses. Daily disposable contact lenses
are the most trouble free modality, with a significantly lower
overall incidence of contact lens related complications when compared
with other replacement intervals. Out of the 35 million contact
lens wearers in the U.S., 85% wear soft contacts and out of these,
22 million wear disposable contact lenses. The issue of safety
and the role of the wearing schedule and contact lens replacement
in maintaining safe contact lens wear have been studied and found
to be safe.
The latest development in the search for the perfect contact
lens has been the approval of the high Dk silicone hydrogel disposable
lenses for extended wear. It is clear that these have largely
solved the problem of hypoxia and are safe but they are not absolutely
trouble free. Some patients are unable to tolerate the lenses
and there are complications like epithelial breaks.
There are various factors for the popularity of contact lenses.
For the patient, the advantages of good comfort and vision, easy
care, ready availability, ocular health are noteworthy. For the
specialist, the benefits of consumer satisfaction associated with
the lowest possible rate of contact lens related problems are
important considerations. Disposable lenses contact lenses are
available in colored varieties, as toric as well as presbyopic
lenses.
Fitting and Care
Before fitting, a careful assessment of the patient is taken
for noting any preexisting conditions that may affect the ability
of the individual to wear contact lenses. Special requirements
like whether lenses are for daily use or occasional use, for presbyopia
or toric lenses are to be used are also important considerations.
Disposable lenses are not to be reused but all users should have
lens care supplies in hand if they have to remove lenses and want
to reinsert them. After cleaning, the lenses should be stored
in a multipurpose solution.
Special uses of Disposables
These lenses are readily available and inexpensive thus popular.
They have therapeutic efficacy in many ocular problems and result
in healing of the ocular surface and improvement in vision. Many
people who do not wear contact lenses on a daily basis have the
option of using disposable contact lenses for occasions like weddings
and parties.
Patients who opt not to have refractive surgery can use disposable
contacts and following refractive surgery; these enhance comfort
and epithelial healing. They are also useful for patients who
have had cataract surgery in one eye.
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