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What
are the risks of laser surgery?
The risks outlined
below apply to both PRK and LASIK procedures. The chances of having a
serious vision-threatening complication are minimal, and there have been
no reported cases of blindness following either PRK or LASIK, says James
Salz, M.D., clinical professor of ophthalmology. However, FDA is aware
of a few instances of severe eye injury requiring corneal transplant.
- Infection
and delayed healing: There is about a 0.1 percent chance of
the cornea becoming infected after PRK, and a somewhat smaller chance
after LASIK. Generally, this means added discomfort and a delay in healing,
with no long-term effects within a period of four years
- Undercorrection/Overcorrection:
It is not possible to predict perfectly how your eye will respond to
laser surgery. As a result, you may still need corrective lenses after
the procedure to obtain good vision. In some cases, a second procedure
can be done to improve the result
- Decrease
in Best-Corrected Vision:
After refractive surgery, some patients find that their best obtainable
vision with corrective lenses is worse than it was before the surgery.
This can occur as a result of irregular tissue removal or the development
of corneal haze
- Excessive
Corneal Haze: Corneal haze occurs as part of the normal healing
process after PRK. In most cases, it has little or no effect on the
final vision and can only be seen by an eye doctor with a microscope.
However, there are some cases of excessive haze that interferes with
vision. As with undercorrections, this can often be dealt with by means
of an additional laser treatment. The risk of significant haze is much
less with LASIK than with PRK
- Regression:
In some patients the effect of refractive surgery is gradually lost
over several months. This is like an undercorrection, and a re-treatment
is often feasible
- Halo Effect:
The halo effect is an optical effect that is noticed in dim light. As
the pupil enlarges, a second faded image is produced by the untreated
peripheral cornea. For some patients who have undergone PRK or LASIK,
this effect can interfere with night driving
- Flap Damage
or Loss (LASIK only): Instead of creating a hinged flap of
tissue on the central cornea, the entire flap could come off. If this
were to occur it could be replaced after the laser treatment. However,
there is a risk that the flap could be damaged or lost
- Distorted
Flap (LASIK only): Irregular healing of the corneal flap could
create a distorted corneal shape, resulting in a decrease of best-corrected
vision
- Incomplete
Procedure: Equipment malfunction may require the procedure
to be stopped before completion. This is a more significant factor in
LASIK, with its higher degree of complexity, than in PRK
- Problems
with a Perfect Procedure: Even when everything goes perfectly,
there are effects that might cause some dissatisfaction. Older patients
should be aware that they can't have both good distance vision and good
near vision in the same eye without corrective lenses. Some myopic patients
rely on their myopia (by taking off their glasses, or by wearing a weaker
prescription) to allow them to read. Such a patient may need reading
glasses after the myopia is surgically corrected. Another consideration
is the delay between eye treatments. If one eye is being done at a time,
then the eyes may not work well together during the time between treatments.
If a contact lens is not tolerated on the unoperated eye, work and driving
may be awkward or impossible until the second eye has been treated
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