| REFRACTIVE SURGERY: Options Available |
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| Throughout history, mankind has experimented with ways to improve
vision with external aids and instruments. Once, not that
long ago, the only option for vision correction came in the
form of glasses or contact lenses. The onset of laser-vision
correction surgery widened those options, bringing people
even closer to perfect vision.
Before the appearance of computers and lasers, the main tools
available to an eyecare specialist were a scalpel, a steady
hand, a medical background and perhaps some engineering knowledge.
The premise was that if they could modify the shape of the
cornea, then possibly they could effect permanent improvement
to their patient's vision. The first procedure to show the
possibility of achieving a positive result was called Radial
Keratotomy or RK. |
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| RK is a procedure in which a diamond blade is used to make micro-incisions
in the cornea in a spoke-like pattern to treat mild
levels of nearsightedness and astigmatism. The number
of incisions and their location is determined
by the degree of nearsightedness. These incisions
allow the sides of the cornea to bulge outward and
thereby flatten the central portion of the cornea.
This brings the focal point of the eye closer to
the retina to improve distance vision. |
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| The first in the line of laser procedures for vision correction was
Photorefractive Keratectomy or PRK.
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PRK is a laser vision correction procedure that uses an excimer
laser to treat mild to moderate levels of nearsightedness,
farsightedness and astigmatism. Rather than making
cuts in the cornea, the PRK process uses an excimer
laser to sculpt an area of 5 to 9 millimeters in
diameter on the surface of the eye. Usually one
eye is done at a time, as functional vision may
not return to normal for several days to several
weeks. There is usually discomfort with PRK until
the cornea heals completely. |
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| Then came one of the most promising and exciting developments in
the world of refractive surgery -
LASIK. |
LASIK, or Laser Assisted In Situ Keratomileusis, is an innovative type of laser vision correction.
The procedure, which is performed on an outpatient basis under
local anesthesia, corrects moderate to high levels of nearsightedness,
farsightedness, and astigmatism. |
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LASIK is a simple, fast and highly predictable surgical procedure
performed in an appropriate sterile environment.
In this procedure, an automated microkeratome is
used to create a corneal flap and the excimer laser
is then used to ablate the cornea. LASIK certainly
proved to be far superior than its predecessors
because of minimal discomfort and faster recovery.
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| Until now, visual disorders including nearsightedness, farsightedness
and astigmatism had been treated with excimer lasers. As a
rule, this treatment had no effect on the visual acuity. Patients
did after the surgery without glasses or contact lenses as
well as they did before the surgery with their visual aids.
But now, a new approach to refractive surgery- Wavefront
Guided Custom LASIK-is primed to transform vision
correction yet again! It can be said that wavefront technology
is the magical "pot-of-gold at the end of the rainbow" to
getting better than perfect vision. Instead of just correcting
defocus (spherical and cylindrical) errors, we can now take
a wavefront image- literally a 'fingerprint' of each person's
optical pathway- and use the information to reduce or even
eliminate higher order aberrations. So, for the first time,
we have technology that can potentially achieve better than
20/20 vision. |
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| Acuity correction involves first determining the individual irregularities
of the human eye that limit the quality of the retinal image.
Light rays enter the eye as flat sheets known as wavefronts.
If the optical system is perfect (which is unusual), these
wavefronts exit the eye as regular, flat sheets. When the
cornea or other components of the optical system have imperfections,
higher order aberrations are created, causing the wavefronts
to exit the eye as irregular curved sheets of light. The ascertainment
of these optical aberrations has been made possible with the
use of a device known as the 'aberrometer'. Following this
measuring procedure, the eye is reconfigured in abstraction
from its irregularities. Then, with reference to the new configuration,
the corneal surface is selectively reprofiled with the use
of a high resolution excimer laser beam. This procedure allows
for an optimal, eye specific correction that is unattainable
without unique customization unlike previous techniques of
laser surgery. |
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| Comparison Chart |
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| - |
RK |
PRK |
LASIK |
WAVEFRONT GUIDED
LASIK |
| Range of Treatment |
Low |
Low to Moderate |
Low to High |
Low to High |
| Technique |
Diamond Knife |
Excimer Laser |
Excimer Keratome |
Wavefront analyzer- Excimer- Keratome |
| Unilateral/
Bilateral |
One
eye at a time |
One
eye at a time |
Bilateral |
Bilateral |
| Intra- Operative
Pain |
None |
None |
None |
None |
| Post- Operative Pain |
Mild-24 hours |
Moderate-24 to 48 hours |
Minimal - 4 to 6 hours |
Minimal - 4 to 6 hours |
| Post-Operative
Medication |
1 week |
1 month or more |
1 week |
1 week |
| Predictability |
Low |
Moderate |
High |
High |
| Risk of Complications |
High |
Low |
Low |
Low |
| Eye Structure |
Weakened |
Unaltered |
Unaltered |
Unaltered |
| Functional Visual
Recovery |
1 week |
3-5 days |
24 hours |
24 hours |
| Days off Work
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1 week or more |
Approx. 4 days |
1 day |
1 Day |
| Contact lens wear
after surgery, if needed |
Difficult and Unsafe |
Safe |
Safe |
Safe |
| Visual Acuity |
Unaltered |
Unaltered |
Unaltered |
Improves |
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| So
finally, the choices are numerous-some good, some not so good
and some better than excellent. The decision is yours to take.
Weigh your options with an open mind and walk into the world
of good vision. |
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