Don Williams, Ph.D. calculated that the aberration-free resolution of
the eye would be 20/6.7 for a 3mm pupil and 20/2.5 for an 8mm pupil.
This would be limited somewhat by the spacing between the
photoreceptors, which would produce an "aliasing" effect.

The godfather of human visual aberration sensing, Ray Applegate,
predicts that the effects of eliminating aberrations on the visual
system depend not only on the Modulation Transfer Function, but also on
the Neural Transfer Function, and the perception of vision.  The
perception of vision would depend on the task, pupil size, and the
subtraction and addition of various combinations of aberrations.

There is also the time-constant variability of aberrations.  In other
words, they can change over time.  It's a very complex subject, and one
which is still in its infancy.  The present goal seems to be optimizing
LASIK algorithms to reduce some of the aberrations that are INCREASED
by refractive surgery, and not in the total elimination of aberrations,
which seems to be a rather insurmountable task for refractive surgery
at this time.

DrG

No.  20/10 simply means you can read letters half the size of 20/20
letters. Obviously a good thing.

ok maybe, if you are presbyopic (over age 40), or have some other near
focusing problem, you might want to undercorrect any myopia or
overcorrect any hyperopia to help you at near.  Often done on one eye
only, this technique referred to as "monovision".

Not if you're young.  Go for it.

Answered well elswhere, but you won't find 20/5 on any normal eyechart.
   You'd have to stand 40 ft from a 20/10 letter to appreciate it, or
80 feet from a 20/20 letter. (or reduce the eyechart to 50% or 25%
respectively).

w.stacy, o.d.

Correction is not usually defined by acuity but by refractive error.  If you
could see 20/ 15 with your glasses before LASIK, then, if LASIK leaves you
with plano refractive error, you will likely see 20/ 15.  If you have
significant higher order aberrations, you may see better after LASIK than
you did before if you choose wavefront correction.

Perhaps you meant by your question:
" Is there a downside to correcting all my myopia with LASIK?"
The only disadvantage comes after age 40, when you will need reading
glasses.  If, after LASIK, you were left with -1.50 myopia, you would be
able to use the computer and see most print without reading glasses after
age 40.  But, of course, you would need distance glasses for driving, TV and
other distance tasks.

Only after age 40.

The limits are in the eye, not in the surgery.  Aberrations in the eye,
opacities in the lens and cornea, spacing of the retinal photoreceptors,
efficiency of the neurons and cortex limit best corrected visual acuity,
even if the surgery gets you to zero refractive error.

Dr Judy

Determine the brand and model of the laser that the doctor will use for your
surgery and go to

http://www.fda.gov/cdrh/LASIK/lasers.htm

and then go to "summary of safety and effectiveness".

If your vision can be corrected to 20/20 or better pre-surgery, you will have
about an 80% chance of 20/20 or better uncorrected post-surgery.

Hope this helps

Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
robopt@execpc.com
~~~~~~~~~~~~~~~~~~
"An expert is a person who has made all the mistakes that can be made in a very narrow field."
 - Niels Bohr

you can not get anyone to see better with LASIK than their best
corrected vision before surgery with eyeglasses.  You can't just make
the prescription stonger and get 20/15 or 20/10 vision if someone was
20/20 before.  Wavefront technology could theoretically improve your
acuity but in practice it doesn't seem to deliver.

most younger healthy people are correctable to 20/15.  better than that
is difficult.  I have seen a few people who can squeek out 20/10 minus.
20/5 is unheard of.

if you are perfectly corrected in the distance, it shouldn't affect
your near vision.  if you are overcorrected, meaning made farsighted,
it won't help you see any better in the distance and it could indeed
affect your near vision.  avoid overcorrection.

As you may have gathered from all these responses is that there is
indeed a catch to obtaining 20/10 vision following LASIK.  The
achievement of an aberration-free eye following LASIK is simply doesn't
happen in the real world, as LASIK introduces its own aberrations.

I remember an interesting factoid about fighter pilot performance told
by the scientist who pioneered the clinical use of contrast
sensitivity, Dr. Arthur Ginsberg, during one of his presentations.  The
factoid was that the fighter pilots with the best visual acuity did not
perform as well in identification and detection situations as those
with slightly less than 20/20 vision.  The suggestion was that high
resolution visual acuity interfered with dynamic visual acuity.

DrG