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Glasses
and contact lenses are only temporary solutions. When you
take them off, your vision blurs again. There are also various other factors,
like allergies, that prevent many people from wearing contact lenses.
And of course, there are times when surgery and only surgery can restore vision.
Radial Keratotomy is an established surgical procedure whose
purpose is to remove or reduce ametropia resulting from myopia
and/or myopic astigmatism. The whole point of RK is to reduce
the central corneal curvature sufficiently so as to move
the cornea's focus back onto the retina.
Today, RK has been almost completely replaced by LASIK surgery. The precision
allowed by a laser, and a generally lower level of complications, has caused
most doctors to move away from RK.
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Do
you qualify for RK?
As with all surgeries, RK has its limitations and hazards. If you are
in good health and your myopia does not exceed -7.00 diopters
or have astigmatism in excess of -4.00, you are probably a candidate
for the procedure. If you can't wear contacts and don't want
to wear glasses, or if your job requires good vision without the aid of glasses,
like a firefighter, Radial Keratotomy is something to look
into. The bottom line is that it is your eyesight and you need to ask yourself if you really need the surgery.
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Every radial keratotomy is different from another. Various tests
are required to obtain information that might alter the
procedure for each operation. This includes information about how much myopia
or astigmatism is present, the degree of corneal curvature, and
the thickness of the cornea. A thorough examination of your eyes
is also done to determine if there are any medical problems that
might interfere with surgery.
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The
patient is given a mild sedative prior to surgery and the eye is
prepped normally. Generally, the non-dominant eye is selected for
the first go-around, with an average minimum wait of one week
before surgery is performed on the dominant eye.
Under no circumstances are both eyes operated upon
on the same day!
During the
operation, the front surface of the eye is numbed with drops. Some
surgeons advocate retro-bulbar anesthesia. However, its use is
not necessarily warranted and some of these cases have developed acute optic
atrophy, resulting in total vision loss. Microscopic radial
slits are then cut into the cornea, without touching the inner eye,
to reshape the corneal curvature (See figure above). This allows light
to focus on the retinal screen, once again permitting clear
vision. The operation is generally bloodless and painless.
Precise
microscopic control must be maintained over the length, depth,
and arrangement of these micro-incisions in order to achieve proper
optical correction. The knife blade used is generally a crystalline
blade like sapphire, providing for the best results and more uniform cuts.
These micro-incisions allow the central cornea to flatten, thus
partially or completely correcting the myopia.
Antibiotic
and cycloplegic drops are then applied and the lid speculum removed.
A patch is then placed on the eye for approximately
2 hours. Other than diligent care to avoid getting the eye patch soiled
or wet, there are no restrictions placed on the patient. Antibiotic drops
are used for l-2 weeks after the surgical procedure. By changing the pattern of the radiating
incisions and incorporating tangential incisions, astigmatism
up to 8 diopters can be corrected.
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For the first 24 hours after the surgery, you may experience some sensitivity
to light, mild scratchiness, and/or redness in the operated eye.
There may also be some pain which is usually alleviated by common,
over-the-counter medication.
Vision is usually good within the first week, but fluctuation of visual acuity from
morning to night can be expected for up to 6 months or longer. Occasionally,
a second operation is needed to reduce any residual myopia.
Glare at
night can also be expected for the same length of time. Some patients
have complained for up to 3 years. However, glare testing
shows no significant glare after 1 year in 99.3% of the cases.
Approximately 83% of patients in the expected range achieve unaided post-op 20/40
(or better) vision. Regression of effect over time has not been observed with the newer techniques.
The range of expected correction for spherical myopia is from <1 to
7 diopters, although higher corrections have been reported.
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