As a (very) general rule, patients with more than about 10.00
diopters of
myopia (nearsighted, shortsighted) vision or more than around
3.00 diopters of
hyperopia (farsighted, longsighted) vision are significantly
less likely to achieve uncorrected vision after conventional or
custom
wavefront
Lasik or
All-Laser Lasik that is equal to their corrected vision before
surgery. To determine your
refractive error,
read your prescription.
Patients with greater than about 6.00 diopters of needed correction
are at a higher risk of corneal haze if
PRK is selected. This elevated risk of corneal haze may be able
to be reduced by the use of 500mg of vitamin C taken orally twice
a day for one week before surgery and at least two weeks after surgery.
Yes, plain old vitamin C. Another technique to reduce the probability
of corneal haze is the application of Mitomycin C to the cornea
during surgery. Mitomycin C is a strong medicine that is appropriate
when needed, but probably should be avoided when possible.
LASEK and
Epi-Lasik are techniques developed to provide
ablation on the surface of the cornea as in PRK, but with a
lower risk of corneal haze. Available studies are inconclusive if
this is actually the situation. For the greatest margin of safety,
patients needing greater than 6.00 diopters of correction may want
to consider Lasik instead of PRK, LASEK, or Epi-Lasik. Lasik has
a very low incidence of corneal haze with higher corrections.
Additionally, patients with
astigmatism that is greater than half their
sphere,
or more than 2.00 diopters are less likely to achieve uncorrected
vision after Lasik, PRK, LASEK, or Epi-Lasik that is equal to their
corrected vision before surgery. All patients with refractive error
beyond these guidelines can expect
regression
and would have a higher probability of a surgical
enhancement.
CK is used for correction of hyperopia and to induce
monovision. CK appears to have best results when inducing no
more than 1.50 to 2.00 diopters of refractive change.
Patients with very high refractive error may find lens-based
refractive surgery a better option.
P-IOLs appear to be most appropriate for patients with moderately-high
to high refractive error.
RLE may be appropriate for a patient with any amount of refractive
error if that patient is fully
presbyopic,
or for patients who have
accommodation with very high refractive error if the patient
is willing to sacrifice accommodation. A significant limitation
of both P-IOLs and RLE is that they may not be able to correct astigmatism.
These are guidelines that not every surgery will agree are accurate
and there is room for disagreement on the issue. Also, an individual's
circumstances may indicate that one procedure is significantly more
safe than another regardless of these general guidelines. We are
a patient advocacy primarily interested in patients avoiding problems
or disappointing outcomes. There are most certainly refractive surgeons
less conservative than our organization. It is also possible that
due to the unique circumstances of the patient, a parameter not
normally considered appropriate would be best. An individual's circumstances
may indicate that one procedure is significantly more safe than
another regardless of these general guidelines.
If your refractive error is so great that you cannot reasonably
expect full correction with
refractive surgery, you may consider having surgery with only
partial correction. However you first need to consider
your motivation for refractive surgery. If the motivation is
to never wear glasses again, you already know that this is not probable.
In this instance it would appear that you will not receive the
outcome you want - not wearing corrective lenses.
You may want to ask your doctor to fit you with contacts or spectacles
that will simulate your expected vision after surgery for partial
correction. This will provide you with an indication of what life
would be like after surgery. Wear these corrective lenses for at
least a month before you decide if the expected visual acuity after
surgery will meet your needs.
Discuss with your doctor if after
surgery you will be able to wear contacts and/or glasses that will
correct the remaining refractive error. It is unreasonable to expect
that your vision after refractive surgery without corrective lenses
will be better than your vision with corrective lenses before surgery.
Don't rush. You have only one set of eyes. If you have doubt that
you will reach the goal that is the basis of your personal motivation,
you should seriously consider deferring refractive surgery until
you and your doctor can reasonably expect a completely satisfactory
result.
The most you can expect from refractive surgery is the
convenience of a reduced need for corrective lenses. To achieve
that convenience, you must accept some risk. While there is risk
in any surgery, the risk of surgery outside these general guidelines
may be unacceptable for most patients.
If you are ready to choose a doctor to be evaluated for conventional
or custom
wavefront
Lasik,
All-Laser Lasik,
PRK,
LASEK,
Epi-Lasik,
NearVision CK,
RLE, or any
refractive surgery procedure, we highly recommend you consider
a doctor who has been evaluated and certified by the USAEyes
nonprofit organization. Locate a USAEyes Evaluated & Certified
Lasik Laser Eye Surgery Doctor.
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