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What is Cataract?
 Human
eye has a natural lens which is normally transparent and forms a clear image of
the outside world in the eye. When this lens develops haziness or opacity, the
sight is decreased or may be completely lost - this is called cataract.
What causes
Cataract?
When a cataract forms, there is a
change in the chemical composition of the lens, but scientists are not clear
about what causes these chemical changes. The most common form of cataract is
related to aging, although this type can occur around the age of 50 or even
earlier. Cataracts also may be associated with diabetes, other systemic
diseases, drugs, and eye injuries. Sometimes babies are born with congenital
cataracts or develop them during the early years of life.
What are the
Symptoms of Cataract?
 Cataracts usually develop gradually,
without pain, redness, or watering in the eye. The most important symptom of
cataract is a decrease in vision or eye sight for distance & or near
objects. Other features can be decreased vision in bright or low light,
decreased contrast, glare, altered color appreciation, seeing many images of
one object, rapid changes in the number or power of glasses, or rarely pain,
redness and watering. Affected persons may have a feeling of having a film over
the eyes and may blink frequently in an effort to see well. In advanced cases
there is complete loss of sight and pupil becomes pearly white in color.
However, none of these symptoms are seen exclusively in cataract. Some
cataracts never progress to the point where they seriously impair vision,
whereas others eventually block most or all vision in the affected eye. The
effect of a cataract on vision depends on several things like - its size, its
density and its location within the lens. In certain types of cataract, night
driving becomes harder because the cloudy part of the lens scatters the light
from on-coming headlights, making these lights appear double or dazzling. Also,
the person with a cataract may have trouble finding the right amount of light
for reading or close work.
What should one do?
The
first thing a person must do on experiencing any of these symptoms is to
consult an eye surgeon (Ophthalmologist) giving details of ones symptoms and
getting ones eyes thoroughly examined. Answers to the following questions
should be sought -
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Do I have cataract ?
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Do I have any other eye disease ?
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What is the cause of cataract in my eye ?
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What are the treatment modalities available ?
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What treatment would be most suitable for me ?
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What is the expected outcome of the treatment or surgery in my
case ?
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What are the risks involved and possible complications ?
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How long can I wait before I get operated ?
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What does the surgery involve in terms of time and expenditure
?
Once it is decided that the patient has cataract the treatment
is essentially surgical, the only question that arises is when? The decision is
patient's - whenever the patient feels his vision has decreased to a level
where he finds it difficult to carry on his routine daily activities he can get
operated (no longer is it required for the cataract to become mature). However,
in certain cases where there are associated complications or potential risk of
complications, an early (even urgent) operation may be required - where the
advice of consulting eye surgeon should be followed.
How is Cataract
Operated?
The
contemporary standard procedures done to remove cataract and restore vision are
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Extra-capsular Cataract Extraction (ECCE) with
Intra-ocular Lens (IOL) Implantation.
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Phacoemulsification with Foldable Intraocular Lens (IOL)
implantation
(No-Stitch Surgery).
ECCE with IOL implantation is the conventional procedure.
It involves making an incision (about 6-8 mm) at the edge of cornea (junction
of black with the white of the eye in the upper part) followed by making an
opening in the capsule of the lens. Through these openings the nucleus (hard
portion) of the lens is expressed and cortex (soft portion) of the lens is
sucked out. IOL is inserted and positioned either inside the capsular bag or
over the capsule (if the capsular support is deficient then IOL is positioned
in the anterior chamber or may not be implanted at all).The incision is then
sutured (stitched) using micro-fine suture material. In most cases these
sutures are not required to be removed.
 In Phacoemulsification the incision is much smaller self
sealing (about 3 mm) and the nucleus of the lens is converted to a pulp using
high frequency ultrasound sound waves and sucked out. Then a foldable IOL is
inserted through this small incision and positioned into capsular bag. The main
advantages of this operation are early rehabilitation and decreased occurrence
of high astigmatism (cylindrical power in glasses). All these operations are
done under local (or topical) anesthesia which makes the eye and surrounding
area numb and senseless, and the patient although conscious does not feel any
pain or discomfort. General anesthesia, which has its own risks, is used only
in children and uncooperative patients.
What is an
Intra-Ocular Lens (IOL)?
 Intra-ocular
Lenses (IOL) are small (5-7 mm) lenses made of Silicone, Acrylic or PMMA, and
are implanted inside the eye in place of natural lens. The greatest advantage
of IOL is a clear wide field of vision and the fact that the patient does not
have to constantly wear thick glasses. However, glasses with low power may be
still be required. The reason being that unlike natural lens the IOL has a
fixed power (estimated by doing pre-operative Ultrasound Biometry) which is
usually adjusted such that the mid-range or routine viewing distances are seen
clearly, and for distances closer or further low powered glasses may still be
needed.. The IOL stays in the eye lifelong and usually does not create and
problem or discomfort to the patient.
"Have realistic expectations" - The surgical
technique and the quality of the IOL are not the only factors that decide the
result of cataract surgery; but also the condition of the eye otherwise, the
cornea, the retina and the presence of systemic diseases like diabetes,
hypertension, asthma, infections, etc. Though the overall results are excellent
with restoration of good vision, yet it is not possible to duplicate nature's
gift of vision.
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