Dear Prevention minded friends,

If you are lucky enough to be close to passing
the 20/40 line, and have a strong minus lens,
perhaps this might explain why you should
be careful about wearing that minus all the time.

If I had this information when I was at 20/50 (as
a child) I don't think I would have worn that
minus all the time (as I was ordered to do).

I would hope that now, a "second opinion" OD
or MD would be wise enough to discuss these
specific issues with you.

_______________________________________________


Subject: Discussion of over-prescription and the reasons for it.
(Over-prescription by -2.0 diotpers creating 20/10
vision -- when there is no requirement for wearing a
minus lens at all.

Condition:


1. You check your eye-chart and read 20/40. You go to the DMV
and pass their visual-acuity test. Now, do you actually
NEED a minus lens.

2. You go to an OD and he checks your eyes under semi-darkness
conditions. By HIS MEASUREMENT he says you NEED a -2.0
diopter lens! Since pass all LEGAL test, I suggest that you
are "over-prescribed" by -2.0 diopters.

3. IN NO SENSE do I suggest that you do nothing and allow your
eye-chart to remain at 20/40. The 20/40 must be a "warning"
to you tha you MUST begin useing the plus to clear to at
least 20/30, 20/25 and 20/20. But that is the reason to not
"accept" the -2.0 dioper over-prescription.

4. IN NO SENSE do is suggest that you drive a car unless you pass
all standards required of you. I just recommend that you
personally verify that you meet that requirement.


DISCUSSION BELOW:

_________________________

>Subject: Re: True Prevention from an OD's perspective

To Dr. Judy,

I do believe that eye doctors are good people who are trying
to do the best job they can with the knowledge they've been
trained in. And I also know that most people want to be fully
corrected. It is just that the entire model ignores the
possiblity of vision improvement.

It isn't the fault of the doctors per se for doing what
they've been trained to do, but if anecdotal evidence challenges
the scientific model -- this should be taken seriously.

My experience may be anecdotal but i can tell you that what i
am experienceing is pretty dramatic. To clarify my own
experience, I had a discussion with the doctor about
undercorrection before the eye exam.

I told him what I was doing and said I wanted an
undercorrected pair of glasses. we talked about this for some
time. We then did the eye exam. He had me to crystal clarity.

I reminded him that I wanted 20/40. It was then that he said
that actually the lenses he had had me looking through gave me
20/15. I said I didn't want that kind of prescription because I
couldn't go anywhere with it.. He responded that he and other eye
dcotors were trained to give people the best vision they could.

He wan't trying to be nasty, but he was clearly very nervous
about giving me a prescription for glasses that wouldn't give me
full prescription.

And in some ways i suppose he was right to be nervous -- i
would have paid a lot of money for those glasses and if i was
unhappy then it would be a problem.

However i never even filled his 20/40 prescrption because I
went a few weeks later to another doctor who came up with a 20/40
prescirption that was significantly lower - and which unlike the
first prescription contained no coorection for astigmatism --
which simply reaffirmed my belief in the variability of vision.

Lisa

drjudy65 wrote:

__________________________

Part 1 From: Judy,

Lisa, you should understand that the vast majority of
patients expect to be corrected fully and would be very upset to
find that their eye doctor deliberately left them a little blurry.

Eye doctors find the refractive correction of least minus or
most plus that provides the patient with his or her best corrected
acuity. Whether the best corrected is 20/20, 20/15 or 20/25
depends upon the eye.

What Otis calls "over correction" is not over correction.
Otis suggests that you wear a correcton that will just barely get
you to 20/40, this is undercorrection, ie it is less than your
true correction. The DMV requirement does not, as Otis implies,
define normal vision. The DMV requirement defines the maximum
amount of visual impairment that will be tolerated in a driver.
Once a driver has more visual impairment than that maximum then
the driver must wear glasses if glasses will deliver better vision
or, if better vision cannot be achieved, then the driver must give
up his licence.

If you want to have glasses that leave your vision impaired
to the maximum amount allowed for driving in your state, then you
should tell the doctor that before the exam starts. Otherwise you
can expect to be corrected to your best possible acuity.

Judy

+++++++++++++++++++++++++++++++++++

Part 2 From: Judy

Your doctor has a duty of care to determine what your best
corrected acuity is; if you don't want it he doesn't have to
prescribe that refractive correction it but he does need, as part
of the medical assessement of your eyes, to determine what BCVA
you can achieve.

As to varibility, there is some natural varibility but you
will find even more if you are determining what amount of
undercorrection will leave you with 20/40. First of all, 20/40 is
a fluid end point. Are you trying to achieve just barely 20/40,
ie almost 20/50 or just barely worse than 20/30. And there will
be a number of ways to degrade your vision to that level --
leaving off the astigmatism is one way, under-minusing is another,
putting the astigmatism at the wrong axis would work or any
combination of the three.

What may be more repeatable with different doctors would be
to ask to be overplussed by a set amount -- say 1.50 diopters and then
check that you can still achieve 20/40 with it.


Judy