|
 Frequently Asked Questions - Contact Lenses
|
|
What are contact lenses?
Who invented them?
How many types are there? and What is the difference between them?
How do contact lenses work?
Can I wear contact lenses?
How do I know if I will have problems?
What about bi-focal and coloured contact lenses?
Why not spectacles?
Continuous care
What are contact lenses?
Contact lenses are very thin, small shell-like discs which are fitted onto the cornea, the clear front surface
of the eyes. They are practically invisible when worn. The lenses move with the
eyes giving a more natural field of vision than is possible with spectacles.
Their purpose is to correct most of the defects in vision for which spectacles
are prescribed, including long and short sight and astigmatism. They can also
correct some eye conditions for which spectacles are of little help.
Back to the top
Who invented them?
They were first described by Leonardo da Vinci in 1508,
then first optical lens being made in 1888. The modern contact lens was
intoduced in 1948 and soft lenses invented in Czechoslovakia, by Wichterle and
Lim in 1961.
Back to the top
How many types are there?
There are six main types of contact lenses;
| |
- Perspex corneal hard lenses (Rigid)
|
| |
- Gas permeable corneal hard lenses (Rigid)
|
| |
- Low water content soft lenses (Soft)
|
| |
- High water content soft lenses (Soft)
|
| |
- Disposable soft lenses (Soft)
|
| |
- Scleral lenses (Rigid).
|
Back to the top
What is the difference between them?
| |
- Corneal lenses were originally made of perspex and called Hard Micro
Corneal lenses. Use of perspex is now dying out as new, more advanced,
hard materials are now available.
|
| |
- Gas Permeable hard lenses, as their name implies, allow oxygen to
reach the eye and waste gases to escape. They may be made from any of the following
materails:
- Cellulose Acetate Butyrate (Low gas)
- Siloxane/Methyl Methacrilate Copolymers (High gas)
- Flourocarbon/Siloxane Copolymers (High gas)
|
| |
- Low Water Content soft lenses (Hydrophilic-water loving) are
pliable and soft. They are usually more comfortable than hard rigid lenses and
do not collect dust during wear. But they are less durable than rigid lenses
and require more careful and vigorous cleaning. These lenses are worn as a
daily wear lens.
|
| |
- High Water Content soft lenses have a water content much closer
to that of the cornea, these permit a greater flow of oxygen to the cornea. This
makes the material suitable for extended wear for up to one week. This type of
lens is also used for daily wear in cases where longer wearing times are required,
or when there are indications of high oxygen demanded by the cornea. These lenses
will need to be replaced at least once a year.
|
| |
- Disposable contact lenses are the newest and most exciting recent
development. These lenses are worn for one week, two weeks or one month, depending
on type and your practitioners recommendations. This type of lens has several advantages
over the more traditional soft lens. Normal contact lenses become dirty with wear which
makes them feel dry and gritty, this is an irritating nuisance that not only
affects quality of vision but may also cause ther problems. Disposable contact
lenses on the other hand, are much safer and more hygienic since you regularly
throw old lenses away and replace them with a sterile new pair. The lenses come
in lightweight blister packs that fit conveniently into your pocket or handbag,
so there is always a supply of lenses on hand. Reassuring if you lose or damage
one. Since you will usually collect your lenses every three months, collection
porvides an ideal time to have your regular after-care check. If you telephone
beforehand for an appointment you can do the two jobs at the same time.
|
| |
- Scleral lenses cover the whole of the front of the eye and are
used for damaged eyes or certain sports as they do not wash out.
|
Back to the top
How do contact lenses work?
A contact lens, soft or rigid, alters the power of the cornea by covering the existing
outer surface with a plastic one, with a leyer of tears trapped between the front of
the cornea and the back of the lens. The lens is washed by tears which are wiped over
the surface by the eyelids, they blink approximately fifteen times a minute. The contact
lens is shped so that it can correct either long or short sight. Some people have
astigmatism (irregular corneal surface) which may mean that a rigid lens will be the best
choice in order to achieve a satisfactory level of vision. For very complex astigmatic
prescriptions a special soft contact lens, called a toric lens, may be the only solution.
As a general rule the level of vision achieved with a soft lens is not quite as good as
with a hard lens. However, in most cases a soft lens will prove more comfortable.
Back to the top
Can I wear contact lenses?
Yes, you probably can, women generally adapt to contact lenses faster than men since
they are used to putting on eye make-up which makes them more adept at handling them.
But, given a little practice, almost anyone could wear them if they wanted to . It should be
remembered that a contact lens is a man made foreign body that sits on the cornea and, as
such, can cause problems, particularly when you consider that they come into contact with
a surface as delicate as eye tissue. The likelihood is, however, much reduced by constant
care from your optometrist. An after-care check is recommended every three months.
Here are some of the obstacles which could make contact lens wear an unsuitable option:
| |
- Reduced tear flow, especially as we get older.
|
| |
- Abnormal tear secretions, too much lipid (fat), protein or mucous.
|
| |
- Sensitive eyes and lids, e.g., hayfever sufferers.
|
| |
- Allergy to care systems can be caused by allergens in the air or preservatives
in the solutions. 8-10% of the population are sensitive to some contact lens
solutions, although this can be detected during your regular after-care checks
and can, very often, be resolved by a change of care system.
|
| |
- Some eyes show long term difficulties with contact lenses. In particular; Recurrent
red eye problems, frequent eye infections, unexpected changes in prescription &
initial difficulty switching back to spectacles upon lens removal.
|
Only 1 person in 100,000 of the population is reported annually as suffering from
corneal ulceration which is the most common serious problem caused by contact lenses.
Your optometrist will advise you of your suitability, following as initial contact
lens examination.
Back to the top
How do I know if I will have problems?
You do not. Your eyes are 10 times more sensitive than the normal skin on your body. The
tissues in and around your eye are delicate and unique. If you intend to introduce a
'foreign body' onto your eye you must be aware of this and be prepared to follow the
optometrists recommendations for hygienic cleaning and attend for aftercare checks
regularly. If you take advantage of the continuous care offered by the optometrist,
any sign of a problem can be detected before it has time to become a problem.
It is up to you!
It is vitally important that the choice of lens is made to suit your visual needs and that
full continuous care is followed through to ensure that any problems that occur with your
eyelids, the cornea or the conjunctiva are detected. Provided that you follow your
optometrists advice properly and conscientiously, you are unlikely to experience any major
problems.
Back to the top
What about bi-focal and coloured contact lenses?
B-focal contact lenses are less succesful than single vision lenses, but with careful
selection they can be succesful in 40% of cases. Other contact lens wearers who
require an additional reading correction can be prescribed and supplied with a pair
of near vision spectacles, for use in conjunction with their contact lenses.
Soft coloured contact lenses can be supplied in a variety of shades. These are
available to prescription or with no power. Have you ever wondered what you would look
like with different coloured eyes? Please remember, cosmetic lenses require just as
much care as any other contact lenses. Prosthetic, hand painted lenses are also available
to special order.
Back to the top
Why not spectacles?
Contact lenses do not restrict your field of vision in the way that some spectacles do,
and since the eyelids act as windscreen wipers to keep the lenses clean, there is no misting
or rain spotting. If you wear spectacles all the time contact lenses have an obvious advantage.
On the other hand, if you only wear spectacles occasionally - just for television or just for
reading - contact lenses could be more of a hindrance than a help. If you are having a lazy
day at home you may want to wear your spectacles, but if you are out and about meeting people,
contact lenses may well ne your preferred choice.
Back to the top
Continuous care
The Wheatcroft Partnership aim to provide the highest possible standards of professional
eyecare at the most reasonable cost. We are not prepared to cut corners in order to cut
prices. To ensure maximum success and safety, contact lens wearers must follow their
practitioners advice with regard to wearing times and hygiene routines, always take
advantage of the continuous care provided for your benefit. After-care is particularly
important for contact lens wearers. Your practitioner may need to see you several times
in the first six weeks, thereafter at three monthly of six monthly intervals. You will
probably have gathered now that the importance of after-care cannot be overstated and
since the first year of after-care in included in the price, it costs you nothing to
retain that peace of mind.
Back to the top
|
|
|
|
|
01482 329545
