Frequently Asked Questions about Lens Exchange
Q: What does a Lens Exchange operation involve?
A: The operation
involves removing the natural lens from the eye and replacing
it with a tiny artificial plastic lens. This is called
the lens implant. The procedure used is called “phacoemulsification”.
Eye doctors often simply call the operation “phaco”.
It is very similar to a cataract operation. A tiny incision is
made in the eye, usually only about 3 mms long to allow the specialised
instruments to enter the eye. These then break up the natural lens
within the eye. The artificial lens is then inserted through the
incision and nudged into position within the eye. Usually no sutures
(stitches) are needed.
Q: What is the intra ocular lens implant?
A: The intra ocular lens
implant (referred to as the IOL by eye surgeons) is a clear plastic
artificial lens inserted into
the eye once the natural lens of the eye has been removed.
Lens Exchange
gets its name from the fact that the natural lens of the
eye is being exchanged/replaced by an artificial lens. The power
of this artificial lens is chosen so as to give the eye the
desired (change in) focus. Without a lens the eye would be
wildly out
of focus. There are different types of lens implants and
they
can be made from a range of plastic materials. Those more
commonly used are made of a flexible plastic. This allows the lens
implant
to be folded so that it can be inserted into the eye through
a very small incision. Once within the eye the lens implant
unfolds and is nudged into position
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Q: How long will the lens
implant last? A: A lifetime. The plastics from which the lenses
are made have been subject to accelerated ageing tests. It is
estimated that
in the eye most lens materials will last in excess of 150
years before showing signs of significant degradation. There have
been some rare reports of certain lens designs becoming prematurely
opaque within the eye. These lenses have been withdrawn from
the market.
Q: Will the lens implant move?
A: If the surgery was routine and
without complications (as is usually the case) it is quite unlikely
that the lens implant
will move out of position. However if the delicate supporting
structures around the implant are inherently weak or were
damaged during surgery it is possible for the lens to move out
of perfect
position. This can affect vision and may mean the need for
additional surgery to correct the problem.
Q: Can I have both
eyes done at once?
A: No. For safety reasons only one eye is operated
on at a time.
Q: How long after the first eye can Lens Exchange
be done on the second eye?
A: Each eye usually takes about 3 weeks
to fully recovery from surgery, although most of the “settling
down” occurs
in the first few days. It is wise to wait until the first eye has
recovered from surgery before doing the second eye. The usual gap
between eyes is therefore about 3 weeks although it can be longer
if the patient wishes.
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Q: What work up is needed before a Lens Exchange
operation?
A: A sight test (refraction) should be done so that
the calculation on changing the focus of the eyes is based on the
most up to
date data. Also some special measurements need to be done of
the eyes from which the power of the lens implant is calculated.
The process of taking these measurements is called “Biometry”.
The main measurements are the curvature of the cornea and the
length of the eye. Biometry is done at the pre-operative assessment.
Q:
Do I need to leave my contact lenses out & if so for how
long?
A: Yes. For the sight test (refraction) soft contact lenses
can be taken out on the day of the test, but rigid lenses should
be
left out for a week. For the Biometry measurements soft lenses
should be left out for 5 days and rigid lenses for 2 to 3 weeks.
This may be inconvenient but it is vital to base the surgery
on reliable eye measurements and these can be affected by contact
lens wear.
Q: What anaesthetic will be needed for the operation?
A: In most
cases only a local anaesthetic is needed without an overnight stay
in hospital. This simplifies the procedure and
minimises the risk to the patient’s general health. There
are a number of different techniques for administering the local
anaesthetic. The precise technique used will depend upon surgeon
and patient preference.
Q: If I have a local anaesthetic will
the operation hurt?
A: The
surgery should be pain free. The surgeon is as keen as the patient
to achieve this because a relaxed patient is the key
to good operating conditions. There are though some sensations.
Some eye drops sting briefly as may the local anaesthetic injection
if one is used. Some patients may be aware of a stretching sensation
from the clip that holds the eyelids open during the operation.
There may be an awareness of a light pressure from the fluids
and instruments in the eye and the touch of the surgeon’s
hands around the eye. A common practice is for a member of staff
to hold the patient’s hand during the operation. By squeezing
this hand the patient can draw attention if any pain or distress
occur. Any problems can then be addressed. The patient should
avoid speaking during the operation unless given the OK to do
so by the surgeon. This is because when speaking the head and
the eye may move and at the wrong moment this might upset the
surgery.
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Q: Will I be able to see what is being done to the eye
during the operation?
A: No. If a local anaesthetic injection
is used this will put the sight (vision) to sleep as well as
removing feeling and
paralysing
eye movement. Even if only anaesthetic eye drops are used the
bright light of the operating microscope will tend to bleach
vision and
the surgical manoeuvres are so close to the eye that there
is little if any visual appreciation of what is happening. The
other eye
will be covered.
Q: Should I take my usual medication on the
day of the operation?
A: In most cases yes but it is best to check
will your eye unit about this. The pre-operative assessment is
a good time to
do this. Arrangements may vary from one eye unit to another
and from one anaesthetist to another so it is not possible to give
all encompassing advice.
Q: What are the risks in having a
Lens Exchange operation?
A: There is a small risk in having any
operation. This is also true for Lens Exchange. In the hands
of an experienced surgeon
the risk of ending up with worse vision as a result of the
surgery is small; perhaps of the order of 1% or less. The risk
of losing
all vision or of requiring removal of the eye after the operation
(e.g. because of an infection) is extremely remote; but it
is not zero. The types of risk involved in having
Lens Exchange surgery include:
- Infection within the eye.
- Bleeding within the eye.
- Disturbance to the retina, e.g. a retinal detachment or a
swelling of the centre of the retina (which affects central
vision). The
latter is called cystoid macular oedema.
- Permanent clouding of the cornea. The cornea is the window
of the eye.
- A long term increased pressure within the eye.
- A drooping of the upper eyelid.
These complications are rare. If they occur further surgery to
the eye may be required. It should be emphasised that in the vast
majority of cases Lens Exchange surgery is uneventful with excellent
results. However this cannot be guaranteed.
Occasionally after the operation the focus of the eye is not quite
as expected. The formulae used to calculate the power of the lens
implant are well tried but are not perfect. This is because of
biological variability between patients, (for example two eyes
may appear the same but identical surgery upon them may not yield
identical results). If the focus of the eye is not acceptable to
the patient some further surgery may be required. This may be laser
refractive surgery (e.g. LASIK or LASEK) or conventional surgery.
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Q: Can the operation go wrong?
A: In a small minority of cases
technical difficulties can occur during Lens Exchange surgery.
The delicate structures around
the natural lens of the eye sometimes break. This can make it
more difficult to remove the natural lens and/or safely insert
a lens implant. For example the very thin membrane behind the
natural lens may rip. This is called “posterior capsule
rupture”. This membrane separates the natural lnes from
the vitreous jelly which fills the main cavity of the eye. If
this membrane breaks the vitreous jelly can move forward into
the front part of the eye. Additional surgical steps are then
necessary to remove this misplaced vitreous. If these events
are correctly dealt with the visual outcome is still favourable
in most cases. Occasionally it is safer not to insert a lens
implant when these complications occur, although this may be
possible at a later date. Very rarely the natural lens may fall
to the back of the eye during surgery. Referral to a vitreoretinal
surgeon in order to remove it will then be necessary. Again it
should be emphasised that in the vast majority of cases Lens
Exchange surgery is uneventful with excellent results. However
this cannot be guaranteed.
Q: What restrictions are there after
the operation?
A: You should always seek, and follow, the advice
of your own eye care team. It is though sensible to avoid any
situation where
you might be hit in the eye and you should not rub the eye.
If your operation was done using a small incision (3mm or
less), as is usually the case, then the eye is quite robust after
the
operation. The wound is unlikely to give way. It is usually
OK to perform light physical activities soon after the operation.
If such activities cause the eye to throb then it is wise
to
stop and rest. Following small incision Lens Exchange surgery
normal activities and past times can usually be fully resumed
after about three weeks. If a larger sutured incision has
been used it may be 2 or 3 months before this can be done and greater
initial restrictions may apply. Always check with your surgeon
if you are in doubt.
Q: How soon after the operation will
I be able to drive?
A: This depends. If you have driving standard
vision and a normal field of vision in the fellow eye then you
may legally drive
a private car on the day following the operation (applies
to UK). However if you have been used to driving using two eyes
it is wise not to drive until good vision has returned to
both
eyes or you have adapted and are confident to drive with
only one eye. The time taken for the eye to regain driving standard
vision after a Lens Exchange operation varies from one patient
to another. Sometimes driving standard vision may be regained
within days of the surgery but this cannot be guaranteed
in
advance. Sometimes new spectacles will be required in order
to obtain
driving standard vision. It is best to ask your surgeon and
not to drive until he or she has stated that your vision has
reached
the required
standard. Do not drive until the effects of the anaesthetic
or any sedation have worn off.
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Q: How soon after the cataract operation can I go back to work?
A: This will vary from patient to patient. It depends on the nature
of your work and the speed of recovery of the eye. Your own ophthalmic
team will advise you. Follow their advice. There are though some
general principles.
Lens Exchange is usually performed using a small incision technique
without the need for sutures. With this form of surgery the eye
usually takes about three weeks to fully settle. For sedentary
occupations it may be acceptable to return to work after about
a week. For work involving physical exertions 2 to 3 weeks may
be preferable. If the job requires good quality well focused vision
then the patient should wait until this is achieved.
If the surgery has involved a larger incision with sutures then
the eye may take 2 to 3 months to fully settle. In these cases
the return to work may be delayed somewhat.
When returning to work (and at other times too) avoid situations
where you might be hit in the eye. Dry or dusty atmospheres may
cause some irritation to the eye but are not directly harmful.
Q: How soon after the operation will I be able to play sport or
swim again?
A: This will vary from patient to patient. Your ophthalmic
team will be able to advise you. Follow their advice. The type
of surgery
will affect how soon these activities can be resumed. Lens Exchange
is usually performed using a small incision technique without
the need for sutures. With this form of surgery the eye usually
takes
about three weeks to fully settle. If the surgery has involved
a larger incision with sutures then the eye may take 2 to 3 months
to fully settle.
It may be wise to wait until the eye has fully healed before returning
to swimming and sports although opinions do vary somewhat between
surgeons. Contact sports and small ball games (e.g. tennis, squash,
badminton) represent the greatest threat to the eye as they carry
a risk of a direct blow to the eye.
The chlorine in swimming pools and the salt in the sea may irritate
the eye a little more than normal in the first weeks after surgery
but are unlikely to be directly harmful.
Q: For how long will I
need eye drops after the operation?
A: In most cases for 2 to
3 weeks, though occasionally it may need to be for longer than
this. Follow the instructions of your
own
eye care team.
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Q: How soon after a cataract operation can I
fly?
A: There are usually no restrictions on flying after Lens
Exchange. The air conditioning within an aircraft may make the
eye feel
a little dry and irritable but this is not harmful. However
do not fly away from post-operative supervision until your
ophthalmic team are happy that the eye has sufficiently recovered
from
surgery.
The only situation where flying may be dangerous after eye
surgery is when a bubble of gas has been placed within the
eye. This
is not done during Lens Exchange. It is sometimes done for
operations on the retina. Gas within the eye will expand at
altitude.
Q: Will I need to wear an eye patch afterwards?
A: Yes. An eye
patch and/or a plastic shield is placed over the eye after Lens
Exchange surgery. If a local anaesthetic has
been used the patient may not be able to properly close the
eye for
a few hours following the surgery. A soft eye patch/pad is
then used to keep the eyelids gently closed over the eye
until the
ability to blink has fully returned. A plastic shield is
also used to protect the eye from accidental pressure. This is
usually
kept in place over the eye until the day after surgery (i.e.
through the night). If a small incision without sutures has
been used many surgeons then dispense with the shield though
some
recommend continuing with it during sleep for several days.
If a larger incision was used with sutures the wound is more
vulnerable
and it may be wise to continue to wear the shield during
sleep/at night for a week or so.
Q: Will I still need glasses after
the operation?
A: Lens Exchange is usually performed to reduce
dependence on spectacles or contact lenses. However they may
still be needed
after the
operation, particularly for near vision. Lens Exchange removes
any remaining ability of the eye to adjust its own focus.
If the eye(s) is focused for distance vision after surgery then
it is likely that spectacles will be needed for clearly focused
near/reading vision. The exact requirement will vary from
patient
to patient and will depend on the original aims of the surgery.
Q:
Is the operation permanent?
A: Yes. The change in focus of the eye
brought about by Lens Exchange is permanent. There is very unlikely
to be any “regression” (drift
back) in the focus of the eye as can occur following laser refractive
surgery. There may though be a slow drift in the focus of the
eye over time as can occur anyway and independently of the surgery.
Some patients do experience a phenomena called “Posterior
Capsular Opacity”. There is a thin transparent membrane behind
the lens implant called the Posterior Capsule. Sometimes months
or years after the operation this can become hazy and vision will
then deteriorate. If this occurs it can be treatment with a simple
outpatient laser procedure.
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