Is figuring out your eye prescription and EXACT SCIENCE...???

I'm curious about this one. If someone were to visit 5 different
optometrists for an eye exam... would all of the prescriptions be
pretty much the same, or would there be major differences?

And.. if they were different, would that be more likely caused by the
different ways that you're tested? The interpretation of the test
results? Other factors?

Thanks in advance

LEESA (I)

Dear Leesa,

Subject: A difference of 1 diopters would be possible between "second-
opinion" ODs and "Best Visual Acuity" ODs.

A good estimate would be about one diopter (1-Sigma).

"Prescribing" is not an "exact science" -- and truly depends on the
person doing the "prescripting".

Enjoy,




On Oct 5, 10:28*pm, LEESA <taylorlee...@gmail.com> wrote:
> I'm curious about this one. *If someone were to visit 5 different
> optometrists for an eye exam... *would all of the prescriptions be
> pretty much the same, or would there be major differences?
>
> And.. *if they were different, would that be more likely caused by the
> different ways that you're tested? *The interpretation of the test
> results? *Other factors?
>
> Thanks in advance
>
> LEESA *(I)

Subject: Remarks on "prescription accuracy" by Dr. J. Raphaelson

Re: Range of accurate prescriptions by 11 measurement authorities.

================


HOW ACCURATE?


Says Richard Carter:

"As early as the 13th century, it was decided that optical glass
lenses were the best means
of correcting the minor defects of ordinary vision. During the next
777 years nothing happened
to change this basic medical belief.

The only widely accepted improvements have been purely technical ones:
More accurate ways of
measuring eye deficiencies."

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

HOW ACCURATE, MR. CARTER?


The following is a copy from "Myopia Control" by O. D. Rasmussen,

(Tonbridge, Kent, Great Britain: Crystlate Printing Ltd.,)


"A father consulted us about his nine-year old daughter who possessed
several
pairs of glasses prescribed over the past few years.

The parent was worried at his girl's constant astenopia and fatigue.

My colleague and I agreed to examine independently and not reveal the
findings for the time being.

In addition we sent the girl, at our expense, to eleven different
ophthalmologists - German,
British, French, American, Russian, Japanese, and an Armenian of
European schools.

Each gave a prescription separately and unknown to one another.

The result was eleven different prescriptions ranging from minus
-2.50D. to minus 14.00D.,

with cylinders from minus -0.50D. to minus -1.75D. and a few with no
astigmatic correction at all.

About six had been obtained under full cycloplegia, and three
apparently under partial cycloplegia.

Both eyes were given identical spheres in a minority, but wide
differences in others.


O. D. Rasmussen

==============

On Oct 6, 8:51*am, Otis <otisbr...@embarqmail.com> wrote:
> Dear Leesa,
>
> Subject: *A difference of 1 diopters would be possible between "second-
> opinion" ODs and "Best Visual Acuity" ODs.
>
> A good estimate would be about one diopter (1-Sigma).
>
> "Prescribing" is not an "exact science" -- and truly depends on the
> person doing the "prescripting".
>
> Enjoy,
>
> On Oct 5, 10:28*pm, LEESA <taylorlee...@gmail.com> wrote:
>
>
>
> > I'm curious about this one. *If someone were to visit 5 different
> > optometrists for an eye exam... *would all of the prescriptions be
> > pretty much the same, or would there be major differences?
>
> > And.. *if they were different, would that be more likely caused by the
> > different ways that you're tested? *The interpretation of the test
> > results? *Other factors?
>
> > Thanks in advance
>
> > LEESA *(I)- Hide quoted text -
>
> - Show quoted text -

On Oct 6, 8:43*am, Otis <otisbr...@embarqmail.com> wrote:
> Subject: *Remarks on "prescription accuracy" by Dr. J. Raphaelson
>
> Re: Range of accurate prescriptions by 11 measurement authorities.
>
> ================
>
> HOW ACCURATE?
>
> Says Richard Carter:
>
> "As early as the 13th century, it was decided that optical glass
> lenses were the best means
> of correcting the minor defects of ordinary vision. During the next
> 777 years nothing happened
> to change this basic medical belief.
>
> The only widely accepted improvements have been purely technical ones:
> More accurate ways of
> measuring eye deficiencies."
>
> ++++++++++++
>
> HOW ACCURATE, MR. CARTER?
>
> * * * * The following is a copy from "Myopia Control" by O. D. Rasmussen,
>
> (Tonbridge, Kent, Great Britain: Crystlate Printing Ltd.,)
>
> "A father consulted us about his nine-year old daughter who possessed
> several
> pairs of glasses prescribed over the past few years.
>
> The parent was worried at his girl's constant astenopia and fatigue.
>
> My colleague and I agreed to examine independently and not reveal the
> findings for the time being.
>
> In addition we sent the girl, at our expense, to eleven different
> ophthalmologists - German,
> British, French, American, Russian, Japanese, and an Armenian of
> European schools.
>
> Each gave a prescription separately and unknown to one another.
>
> The result was eleven different prescriptions ranging from minus
> -2.50D. to minus 14.00D.,
>
> with cylinders from minus -0.50D. to minus -1.75D. and a few with no
> astigmatic correction at all.
>
> About six had been obtained under full cycloplegia, and three
> apparently under partial cycloplegia.
>
> Both eyes were given identical spheres in a minority, but wide
> differences in others.
>
> O. D. Rasmussen


Thanks for this useless anecdote, Otis.

What conclusions do YOU think people should draw from reading it?

Hint: none.

Google "sample size" and -- with some form of Divine Intervention --
perhaps you'll understand why.

I rather doubt it, though.

Also, Otis, please help the OP understand the impact of cycloplegia,
dynamic retinoscopy, and the advent of auto-refractors on the
variability of prescriptions, and -- which PATIENT-centric factors (as
opposed to clinician factors) may affect the variability of Rx's.

Thanks again.

Most presriptions are going to be very similar. However, many things
can contribute to differences in your endpoint Rx (blood sugar levels,
instructions by doctor, room length, dilation drops, visual demands,
etc). Additionally the type of eye disease you have (nearsightedness,
farsighteness, astigmatism) can alter the final prescription that the
doctor may want to prescribe.

Also remember there is a very likely chance that the type of doctor
you go to (Optometrist, O.D. or Ophthalmologist, M.D.) will alter the
way the prescription is actually written since they use different
"language to write the prescription."

I think that being within one diopter is a little too broad, but
somewould argue 1/2 of a diopter is to broad.

Bottom line is what you can see in the glasses/contacts when all is
said and done. Is your vision clear and comfortable? Then the
prescription is probably "correct."


On Oct 5, 9:28*pm, LEESA <taylorlee...@gmail.com> wrote:
> I'm curious about this one. *If someone were to visit 5 different
> optometrists for an eye exam... *would all of the prescriptions be
> pretty much the same, or would there be major differences?
>
> And.. *if they were different, would that be more likely caused by the
> different ways that you're tested? *The interpretation of the test
> results? *Other factors?
>
> Thanks in advance
>
> LEESA *(I)

> > I'm curious about this one. *If someone were to visit 5 different
> > optometrists for an eye exam... *would all of the prescriptions be
> > pretty much the same, or would there be major differences?
>
> > And.. *if they were different, would that be more likely caused by the
> > different ways that you're tested? *The interpretation of the test
> > results? *Other factors?

Another reason they can vary is if you, the patient, are not paying
rigorous attention to whether "this one" or "that one" is better while
you're being examined. If you give different answers during different
exams because you're tired, or because you can't tell and are
guessing, you can get a different scrip.

Liz
Indianapolis

> I'm curious about this one. If someone were to visit 5 different
> optometrists for an eye exam... would all of the prescriptions be
> pretty much the same, or would there be major differences?
>
> And.. if they were different, would that be more likely caused by the
> different ways that you're tested? The interpretation of the test
> results? Other factors?

Should not be major differences, but likely would be some differences:

Your vision is going to vary depending on how tired your eye muscles are,
and your overall health. A bad nights sleep could make a difference. Morning
vs. evening eye exam could make a difference. Some people will be affected
by caffeine or high sugar intake.

The patient responds to questions about which is better (1 vs. 2)
inaccurately or inconsistently from one exam to the next.

Provider takes less time to give exam than another provider (if possible,
don't get an exam when the provider is very busy).

Some providers are just more skilled than others (probably the least likely
reason).

Some providers over-prescribe just a little (err on the strong Rx side).
This is especially true if the provider tries to customize the Rx to a
particular lifestyle or intended use, whereas another provider might write a
more generic use Rx.

Some Rx's look significantly different, but are actually virtually the same
(one with minus cylinder versus one with plus cylinder).

If a provider has a particular lens brand/model/material in mind, they might
slightly alter the Rx based on their experience with a particular lens.