-
Cataract Surgery Restoring Vision with New Techniques and
Innovations Cataracts represent a clouding of the lens of the eye.
Light rays w hich enter the eye are blocked or scattered, resulting
in problems such as blurred vision and glare. Some patients even
experience double vision. In most cases, cataracts develop as a
result of aging changes in the eye. Cataracts may also be caused by
other diseases like diabetes, as a side effect of some medicines,
and from injury to the eye. There are no medicines w hich can cure
a cataract. How ever, cataract surgery has become very successful
and is one of the most common eye operations performed w
orld-wide.
Important Advances in Cataract Surgery
Phacoemulsification Phacoemulsif ication refers to surgery where
the cataract is broken up w ith ultrasound energy and removed
through a small incision. Because surgery is performed through such
a small incision, recovery is rapid. Many patients achieve good
vision by the f irst day after surgery. In most cases, stitches are
not needed, resulting also in faster recoveries and better comfort
after the operation. Because phacoemulsif ication is a fast and
safe operation, most patients have surgery as a day case procedure.
The surgery itself usually takes 20-30 minutes, and is a painless
procedure.
Figure 2 Small incision phacoemulsif ication cataract
surgery.
a The cataract is first broken up and remov ed with
ultrasound wav es from a hollow needle.
b An intraocular lens is injected.
Figure 2a
Figure 2b
Dr Por Yong Ming MBBS (Melbourne), FRCS (Edinburgh), FRCS
(Glasgow), MMed (Ophth)(Singapore), MRCOphth (London) Dr Por
graduated from the University
of Melbourne in 1997 with honours and began ophthalmic training
in the United Kingdom in 1999. While in the
UK, he trained at the Manchester Roy al Eye Hospital. He then
returned to Singapore in 2001 and worked at
the Singapore National Ey e Centre. He presently practices at
Jerry Tan Eye Surgery at Camden Medical
Centre.
Dr Por's strengths are in ref ractive surgery ,
phacoemulsification cataract surgery , v arious forms of
corneal
transplantation including anterior and posterior lamellar
grafting, and external eye diseases. He is also
trained as a comprehensiv e ophthalmologist and has extensive
experience treating other ey e
diseases including glaucoma.
Figure 1a A normal eye.
Figure1b A cataract blocking light entering the
eye, causing blurred vision.
Bahasa Indonesia version...
http://www.jerrytan.com/docs/operasi_katarak_kencan_edisi_6_tahun_1_2011_id.pdf
-
Lens Implants Because a cataract operation removes the natural
lens of the eye, lens implants are needed to replace the original
cloudy lens. By implanting lens replacements, there is no need for
thick glasses or contact lenses after surgery. Furthermore, by
customizing the lens implant, cataract surgery has become one w
here vision can be enhanced and w here spectacle freedom becomes
possible.
Customizing Lens Implants Various formulas have been invented
based on the eye’s corneal curvature as well as the length of the
eyeball, to help choose the best lens for the low est spectacle pow
er. Almost all degrees of long or short sightedness can be
corrected in this way. Measuring the length of the eyeball has
traditionally been accomplished by using an ultrasound machine.
More recently, using a laser beam w ith the IOLmaster machine has
allow ed this measurement to be done w ith 5 times greater
accuracy. In most cases, using such an instrument to predict the f
inal pow er of the eye results in refractive power of +/-50 degrees
(0.50 dioptris) after cataract and lens implant surgery.
Correcting Astigmatism and Presbyopia Astigmatism and presbyopia
are 2 other problems for which people require spectacles to see
clearly. Of late, 2 new lenses have helped to solve these problems.
Where a toric lens w as traditionally used in a pair of spectacles
for astigmatism, they are now available as lens implants to be used
during cataract surgery (Figure 3a). These toric lens implants
correct astigmatism of as high as 400 degrees. In order to achieve
astigmatism correction, the lenses must be aligned exactly
according to the direction of astigmatism of the patient’s cornea.
Specialised photographs and planning programs help in deciding the
optimal position for the lens (Figure 4a and 4b). In combination w
ith accurate biometry w ith the IOLmaster, they virtually remove
the need to w ear glasses for distance.
To address presbyopia (rabun tua), mult ifocal lenses are now
the most w idely employed method. These lenses are most commonly
diffractive in nature, which means they use a series of rings
etched on the lens surface to split incoming light rays into 2
foci-one distant focus and one near focus (Figure 3b).. They have
several disadvantages. Firstly, the presence of the rings means
that in certain situations, and especially at night, light sources
w ill appear w ith a halo and ring around them. Contrast is reduced
and images may appear a little darker.
The other type of lens that is sometimes used to address
presbyopia is the accommodating lens (Figure 3c). These lenses are
f lexible, and this property allow s changes in their position w
ithin the eye to take place. This allows their focus to shift,
allow ing clear near as well as far
Figure 3a A toric lens
Figure 3b A multifocal lens
Figure 3c An accommodativ e lens
Figure 4a Planning a toric lens implantation. First, the optimal
position of the lens is determined
using a specialized computer program
Figure 4b A photograph of the
ey e is taken, and a protractor is ov erlaid to help with
lens
positioning
Bahasa Indonesia version...
-
vision w ithout the halos and reduced contrast seen w ith mult
ifocal lenses. How ever, their effect is not predictable and the
movement of the lens may not be enough in some patients. The
perfect, fully accommodating intraocular lens remains a target of
research for ophthalmic scientists. In conclusion, cataract surgery
has progressed rapidly in the last few decades. From having to w
ear thick glasses after surgery and lying in a hospital bed for a
week, to current day case surgery and better spectacle free vision
than ever. In the future, femtosecond lasers will speed up cataract
surgery and improve safety, and w e await the holy grail of lens
implant surgery-the fully accommodative lens implant which w ill
return our vision to a state truly like that of a young eye.
Advances in Lens Implants
Toric lens • Corrects astigmatism of up to 400 degrees
• Patients with more than 100 degrees of corneal astigmatism
will benefit
• Most patients do not have to wear glasses to see in the
distance after surgery
• Requires precise alignment to achiev e effect
Multifocal Lens • Giv es reasonably good vision at near (about
1foot) and in the f ar distance
• Most patients do not need to wear spectacles at all after
surgery
• Best for patients with minimal astigmatism
• Requires very accurate measurements of the ey e
• Causes halos around lights, especially at night
• Causes decreased visual contrast compared with a normal
monofocal lens
Frequently Asked Questions About Cataracts and Cataract
Surgery
Q: Who requires cataract surgery? A: Once a patient develops
cataract that is dense enough to blur vision even w hen wearing
glasses, he/she will benefit from surgery. Q: Will cataracts cause
blindness? A: If left alone, cataracts will slow ly become denser
over time, and cause vision to become blurrer. By themselves, they
do not cause total blindness, since they can be operated on even w
hen very dense. Sometimes, very dense cataracts can cause a severe
kind of glaucoma. If this develops, permanent blindness can result.
Q: How long does it take to recover from cataract surgery? A:
Recovery of vision after cataract surgery is very fast. In most
cases, vision the next day after surgery is good enough to do most
things like w atching television and even driving. How ever,
patients should remember that there is still a w ound in the eye w
hich takes up to a month to heal. They should not rub their eyes
and avoid activities where a lot of w ater gets in the eye, such as
sw imming. Besides this, the spectacle pow er of the eye takes
about one month to stabilize, and patients should w ait for this
period of time before getting new spectacles. Q: What can I do to
prevent cataracts? A: Cataracts are usually an age related problem,
so they cannot be totally prevented. How ever, studies have show n
that a diet rich in certain nutrients may delay the onset of
cataracts. These foods include colourful fruits and vegetables
which contain antioxidants such as vitamin A, C and E. Lutein is
another antioxidant and is found in dark green leafy vegetables.
Finally, it has been show n that smoking causes cataracts to
develop faster and smokers should quit as soon as possible.
Bahasa Indonesia version...