"otisbrown[at]pa.net" <otisbrown[at]pa.net> wrote:

- quote -

Along with the (more than occasional) MEDICAL advice, in violation of
Pennsylvania law.

--
Live simply so that others may simply live

its nice to know what your "guesses" are.

he needs a careful manual refraction-- as we have discussed ad nauseum
autorefraction is imperfect to say the least.

Dick Adams wrote:

- quote -

do you think this guy posted here so that he could read the "guesses"
of total novices?


- quote -

please disregard this statement. autorefraction is totally not
dependable. get a good manual refraction.

- quote -

true

Dear Charles,

Since these majority opinion ODs love to give me
a "hard time" about ANYTHING
is might suggest, you might
contact me on my site.

www.myopiafree.com

Just remember, the second-opinion is
different than what you received.

But remember, I am an
ENGINEER, and only provide
ENGINEERING advice.

You are old enough and wise
enough to undrstand the issues.

Best,

Otis

Dicky blurted out:
"My guess here is that you should.." and "My belief is.."

thanks for letting us know your guesses and beliefs

"be refracted with a state-of-the
art autorefractor"

wrong suggestion. autorefraction is usually inaccurate. a competent
manual refraction is superior 99% of the time.

"Dick Adams" <bad.addr[at]nonexist.com> wrote in message
news:mH1wf.1418$7l4.1291[at]trndny03...

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"Subjective refraction" has a very specific meaning in the field of eye
care, but Wikipedia isn't specific to this field.

Essentially, subjective refraction is a carefully-presented set of choices
where we rely on you, the patient, to say "subjectively" that more of this
is blurry or less of that is blurry or that the two choices ("1 or 2") are
equal and indistinguishable. Bottom line, the reason I prescribe "+2.25" is
that the patient told me +2.50 was (subjectively) blurrier than +2.25, and
that +2.00 was not better than +2.25. Because these results are "manifested"
from your choices, subjective refraction is often called "manifest"
refraction.

"Objective" refraction refers to measurements taken with instruments that do
not rely on a subjective response. Autorefractors are "objective."
Retinoscopy is a similar technique that yields an "objective" value without
relying on subjective responses. Autorefractors and retinoscopy often agree
more closely than either of them match the final "subjective" refraction.
When I'm looking for maximum accuracy, I'll often do all three and compare
Quite often I do all three.

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If A differs from B by 1.25 units, that's a numerical value that isn't
terribly open to subjective interpretation.

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So would we, but at this point in my career I'm content to leave it to Nikon
and Topcon to figure that out. The best they can do is produce a
_consistent_ instrument - one that finds the same measurement every time. In
that, they've made major advances in the last 20 years, and the results are
quite useful for large-scale studies where before-and-after results must be
compared. So autorefractors (and retinoscopy) measure _something_ very
consistently but it seldom matches exactly what patients choose
subjectively.

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"Means nothing" isn't accurate. What it _does_ mean is we have some starting
point besides Snellen acuity. That's important because depending on age and
circumstances, "20/100" could be the result of 2 diopters of hyperopia, 1.5
diopters of myopia, 3 diopters of astigmatism at any axis, usually in
combination. It would be silly to wander around for 5 or 10 minutes trying
to find the right ballpark to start in, when retinoscopy can produce a
consistent, useful starting point in about 15 seconds per eye.
Autorefractors are even faster, if you don't have to get people up out of
one chair and into another room.

- quote -

You're right. It's all hocus pocus. We just pluck the final numbers from the
air so if it's wrong, we make up new numbers

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Nor can I.

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Again you seem to assume she just plucked numbers from the air. If she
actually performed a subjective refraction, it meant she placed more
importance on _your_ reported observations than on an estimate generated by
a machine. If she was adequately trained, she knew how to present those
choices so your answers were meaningful. I have no patience with incompetent
refractionists.

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No, problem refractionist. In this situation, a good refractionist will use
bigger steps - 050 instead of 025 - to bracket the endpoint.

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We can cite many examples of HMOs cutting corners. That doesn't invalidate
the good refractionists.

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A large variance wouldn't surprise me. I'm the only one who knows how to do
it right.

-MT

Dick Adams wrote:
- quote -

Forget Wikepedia here, as it talks in generalities. In refraction,
subjective and objective mean something different, and something very
specific. Objective means a refraction that requires no patient imput,
just cooperation (e.g. "look at the light; thanks, all done").
Subjective means a refraction that uses (and requires) patient input
(.e.g. "which is better, 1 or 2?). Nothing more, nothing less.

Objective refraction is great, and sometimes I prescribe from it, but
most times I like to hear a patient confirm that it is "better" before I
prescribe it.

w.stacy, o.d.

"Mike Tyner" <mtyner[at]mindspring.com> wrote in message news:_4Yvf.3586$ZA2.2806[at]newsread1.news.atl.earthlink.net...

- quote -

Subjective and objective mean something else to me -- or maybe not. This
excerpted from Wikepedia:

Formed, as in opinions, based upon subjective feelings or intuitions, not upon
observation or reasoning, which can be influenced by preconception; coming
more from within the observer rather than from observations of the external
environment

resulting from or pertaining to personal mindsets or experience, arising from
perceptive mental conditions within the brain and not necessarily from external
stimuli.

lacking in reality or substance

- quote -

Well, that would be a subjective comparison. Nonetheless, I would be interested
to know why the autorefractor fails, if and when it does.

Two human refractors who started my exam with an autorefractor have told
me that the autorefractor results mean nothing. Did I ask "Why do you use
it then?". Well, I am trying not to appear to be a problem patient, so I didn't.

- quote -

I understand that accommodation cannot be controlled so the autorefractors may
not give the right spherical correction. The relaxed eye ideally should focus a point
on the horizon, and be optometrically corrected to do that if it does not do that
naturally. I thought it is the purpose of the drops to relax they eye for that purpose,
but heck, maybe it is just to make the pupils huge. Maybe it is just another element
of the hocus pokus.

Case of me, I never saw an autorefractor until after I had been implanted. These
silicone things do not accommodate. So I cannot understand why the human refractors
were so dismissive of the autorefractor results.

Last time I grabbed the autorefractor tape. I have got it somewhere, and can give
a numeric report when I find it. I recall that the human refractor backed of just a
bit on sphere, but also on cylinder. I could understand about sphere, on the basis
of depth of field, but not about cylinder, especially as my moon image still has ears.
But, when it comes to man against machine, I guess the man wants to feel that he
is still the boss. (Actually one of 'em was a lady.)

I have had a lot of silly conversations with the human refractors. Recently I went
back to one with a complaint, and the answer was "Well, you know, we only know
what you tell us." I guess that refers to our answers to the "This ... .... or this?"
questions. Once I was totally ignored saying "But I can't hardly see line 3 either
way". Problem patient!

I should point out that quite a bit of my more recent experience has been with
human refractors who received their training from the opthamologists who
employed them. That seems to be a HMO phenomenon.

I have wanted to interest some investigative TV show into sending reporters
to various eyeglass purveyors with the story that they had lost their glasses and did
not know their prescription, so as to be able to do some statistical analyses on the
range of prescriptive values which were obtained.

--
Dicky

"Dick Adams" <bad.addr[at]nonexist.com> wrote

- quote -

It's obvious you haven't compared subjective and objective refractions very
often.

In my office, we do both, in the course of every examination. Half the time,
they're pretty comparable. That's fine if 50% accuracy is good enough for
you.

- quote -

You're absolutely right. So why would you assume that the subjective
refraction never includes both eyes?

And why would you think people would be happier with glasses made from
cycloplegic examinations? It might work if they used cycloplegic drops every
day from then on.

-MT

"Charles" <nospam[at]nospam.com> wrote in message news:MsUvf.471082$084.97684[at]attbi_s22...

- quote -

My guess here is that you should, with your focusing ability entirely
shut down with appropriate medications, be refracted with a state-of-the
art autorefractor. Then, if an OD wishes to diddle the autorefractor numbers,
he should be able to explain to your ultimate satisfaction why that is necessary.

My belief is that the individual eyes will have a much easier time if they can
accommodate as a team, rather than separately, but what do I know, as I an
neither an OD or a systems analyst?

--
Dicky