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What does cataract surgery involve?
Although this is major surgery, it is not a prolonged procedure and
usually lasts from 20 to 45 minutes.
While the surgery can be done under local anaesthesia (which involves
usually a small injection at the side of the eye) there is a requirement
for the patient to keep very still for certain parts of the operation,
and my personal preference for patients in reasonable general health
is for a short, light, general anaesthetic, when possible patient movement
is not a risk. After such an anaesthetic, patients are usually wide-awake
after 15 minutes, and nausea is now very rarely a problem.
Whether a local or a light general anaesthetic is used, I prefer the
patient to stay in the BUPA Murrayfield Hospital the night of the operation,
I check the eye the following morning, and if all is well, the patient
may then go home. As I tend to operate in the early evening, patients
are usually in hospital for less than 24 hours. Should there be any
early post-operative problems it occasionally becomes necessary for
the patient to stay in hospital longer.
How exactly is the surgery done?
All cataract surgery involves making an incision in the wall of the
upper part of the eye, through which the whole natural lens is removed,
and a small plastic lens, a lens implant, is inserted through the same
incision, to replace it .
There are basically two "small-incision" techniques to remove
cataracts.
 1.
Small incision extra-capsular cataract extraction, which I tend
to prefer, in which the cataract is removed in a single piece through
a specially constructed small incision.
Place
your mouse cursor/pointer here to view the animated diagram opposite
of a cataract being removed in a single piece.
(79kb, may take 30 seconds to download)
2. Phaco-emulsification cataract extraction,which I use when
appropriate, in which the cataract is broken up inside the eye into
small pieces and then removed using a special ultra-sonic hand-piece.
This technique is not illustrated.
The next steps are similar in both techniques, in that a small suction
probe is used to remove the remaining soft lens matter, and the lens
implant is then inserted into the eye, using the transparent lining
layer of the back of the natural lens (the lens capsule) to help support
it.
I tend to prefer to use lens implants made of a hard plastic material
(polymethyl methacrylate PMMA) which  has
been in use for over 40 years and is known to be totally inert within
the eye. I usually use a 6 or 7 mm lens implanted through the original
cataract incision. These lenses
can also be used after phaco-emulsification if the 3-4 mm phaco emulsification
wound is enlarged.
Place
your mouse cursor/pointer here to view the animated diagram opposite
of a lens implant being inserted.
(58kb, may take 30 seconds to download)
It is currently possible to use a lens implant made of one of several
softer materials, which allow the implant to be folded in half and
inserted through a 4-mm incision, and these lenses are now often used
after phaco-emulsification. I do not use these lenses routinely.
Lens implants require no care, remain in the eye permanently and
are not felt by the patient. The tiny implant gives clearer vision
but cannot vary its focus to give clear vision at all distances, so
that spectacles will still be required for distance or reading, or
sometimes for both.
How long is the recovery period?
For the majority of patients, much shorter than it used to be.
The days of prolonged immobilisation and lengthy hospital stays are
long gone, and for most patients the hospital stay is for a maximum
of one night.
In many places, particularly when cataract surgery can be done in
the morning or early afternoon, it is performed on a "day-case"
basis without staying in hospital at all. However, even then, there
is still a requirement for the patient to be checked at some time
the next day.
Personally, I prefer operating with a one night hospital stay, as
firstly I tend to operate in the early evening and I think patients
benefit more from an undisturbed night in hospital than from rushing
home and then having to return to the hospital to be seen again the
following morning, and secondly, many of these patients are elderly,
live alone and I feel that as the first night is when they may experience
some discomfort, they are more reassured to feel that appropriate
pain relief and skilled assistance is easily at hand in hospital.
There are really very few restrictions on activities nowadays, although
swimming and vigorous physical activities are not advisable in the
first two weeks. There is no need to limit normal activities such
as bending or hair washing.
Often, different spectacles will be needed, but it is usually unwise
to have these prescribed until 3 to 6 weeks after the surgery, even
if the surgery has been performed using a very small incision.
Normally patients go home with eye-drops which are designed to prevent
infection and reduce inflammation, but these are only required for
a few days, depending on the response of the eye to the surgery.
Most patients can manage these drops without difficulty themselves,
and I have all patients instil simple antibiotic eye-drops four times
daily into both eyes for three days prior to the surgery. This significantly
reduces the risk of surface infection being present at the time of
surgery, and gives the patient practice and confidence in the use
of eye-drops. Patients who have difficulties putting in their own
drops have the different techniques of drop instillation demonstrated
to them by my nurse Mrs Diane Ross.
Are there any tests needed before surgery?
It is important to have details about a patient's general health,
including any medication that they might be taking, and this information
is usually provided in the family practitioner's letter of referral.
We also need to measure the degree of curvature of the front of the
eye (cornea) and the exact length of the eye. These tests (referred
to as "ocular biometry" are brief, use optical and ultra-sonic
equipment, are quite painless and are usually done a few days before
the surgery. This information is then fed into a computer which uses
special formulae to calculate the power of the lens implant to be
inserted for that particular patient. Although these are sophisticated
tests, there is still individual variation, and it is never possible
to guarantee that glasses will not have to be worn for distance.
The patient will also be asked to read and sign an informed consent
for the operation, indicating that he or she understands the options
regarding the procedure, and the possible complications.
What are the possible complications?
In about 95% of patients there are no complications whatever.
Minor complications which usually recover completely, include raised
pressure or bleeding inside the eye, temporary water-logging of the
front of the eye (corneal oedema) or of the back of the eye (macular
oedema) and a tendency for the upper eyelid to droop slightly (ptosis).
Rarely one of these may cause permanent effects.
More serious complications would include retinal detachment (1% of
cases) and infection within the eye (endophthalmitis - approximately
in 1 in 3,000 cases). Both these conditions are treatable if detected
early enough, but may result in permanent and severe visual loss,
including blindness or loss of the eye (very rare).
It is important to understand that the risk of these complications
is intrinsic to the surgery itself, and can occur even if the operation
is performed well by an experienced surgeon. The occurrence of one
or more of these complications does not mean that the operation was
badly performed.
Opacification of the lens capsule
This is not strictly speaking, a complication, as it can be expected
to develop eventually in up to 50% of patients who have had cataract
surgery.
What happens is that the previously clear posterior capsule (which
is the transparent lining layer of the back of the natural lens that
provides support to the lens implant) gradually becomes clouded, and
the patient reports gradual blurring of vision. The diagnosis can
usually be confirmed by the optometrist (optician), and the patient
referred back to the eye surgeon. Treatment of this problem involves
clearing a central area of the opaque capsule using a special laser
(and this is the only time that lasers are used in cataract surgery).
This is quite painless, and is almost always done as an out-patient
procedure. As it is another procedure, it does have its own risks,
which are macular oedema, retinal detachment or dislocation of the
lens implant, and the risk for each of these is the same at about
1%.
Possible complications of the anaesthesia
Injection of local anaesthetic around the eye can cause local bruising
which is occasionally sufficient to cause postponement of the surgery,
and very rarely indeed the injection needle used can cause permanent
damage to the eye muscles or to the eye itself.
The type of general anaesthesia used in cataract surgery is fairly
light with few complications but the occasional patient may suffer
some throat discomfort or nausea immediately after the surgery. Serious
complications such as breathing or circulatory difficulties are extremely
rare, but have been described during or after cataract surgery.
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