Inconsistent Medical Study Results

Dear Friends,

I separate pure-science from pure-medicine.

In science, you do an experiment -- i.e., to
prove that the natural eye is dynamic, and
you get the same result however many times
you repeat the experiment.

In medicine, you apparently NEVER get
the same result twice!

Read and enjoy the contradictions!

The concept of "the second opinion" and your
right to use it still stands.

Best,

Otis



Subject: Re: Is the minus lens safe?

Dear Judy,


I want to thank you for your definition of OD preception of
facts concerning the behavior of the natural eye. i.e., the
results all animal studies will be rejected by you, concerning
proof that the natural eye is dynamic (on an "input" versus
"output" form of scientific testing.)

I also believe that all the ODs have the same opinion you do
about "animal studies".

If not, I would like them to state otherwise -- and why.

But I will forward your commentary to other interested
parties.

Please note that JudyDoc NEVER provides a "straight" answer
to a "traight"question. The answer is either "yes" or "no" --
with no bull.

Instead she provides an endless stream of "faulted" studies
to justify te "avoiding" objective scientific facts.

Also note that other ODs are at last willing to change, i.e.,
use a plus on THEIR OWN CHILDREN. That does make the proper use
of the plus "the second-opinion". None of these ODs should ever
"start" you in a plus lens until they have had the "preventive"
discussion with you.


Best,


Otis

Engineer


********

Otis> The ODs insist on "proof" with no definition of it. I
don't know what they are thinking, but it is not of science,
nor part of science in my opinion. This is the "majority
opinion". There are a growing number of ODs and MDs who
acknowledge that is is wise to "go slow" with that minus
lens.


____________________________


I have reviewed a great deal of experimental data. This is a
report on the fact that the natural eye changes its refractive
status when a minus lens is applied externally. I obtained a
report from Howard Howland, and asked him to verbally confirm the
following -- which he did.


Frank Schaeffel, Adrian Glasser and Howard C. Howland,
"Accommodation, Refractive Error and Eye Growth in Chickens",
VISION RES., Vol 28, No. 5 pp 639-657, 1988. Pergamon
Press.


RESULTS:


o All eyes treated with positive lenses became consistently more
positive (hyperopic).

o Negative lenses produced more negative (myopic) refractions
(focal states) in all eyes.

o In a test of plus/minus lenses on left/right eyes, the eye with
the plus lens moved in a positive direction. The eye with a
minus lens moved in a minus direction.

o The control group did not change significantly in any direction.


DrJudy then reports the following:

__________________________



From: Dr. Judy,


Here is one with chicks: the birds wore minus lenses to
correct myopia and, despite wearing the lenses, recovered from the
myopia i.e., they became less myopic.


Properties of the feedback loops controlling eye growth and
refractive state in the chicken.

Schaeffel F, Howland HC.

Forschungsstelle fur Experimentelle Ophthalmologie, Tubingen,
F.R.G.

Recent experiments in chickens provide evidence that axial
eye growth and refractive state are guided by mechanisms sensitive
to refractive error. To determine whether or not the sign of
refractive error is derived from longitudinal chromatic aberration
we raised chicks with spectacle lenses in monochromatic light.
The eyes showed an appropriate growth response to correct for the
defocus imposed by the lenses no different than in previous
experiments in white light.

Thus, in normally accommodating chicks chromatic cues are not
necessary for emmetropization to occur. We examined the linearity
of feedback loops controlling axial eye growth: positive
spectacle lenses were found to inhibit axial growth very
efficiently making the eyes shorter than normal whereas negative
lenses had little effect on axial elongation: feedback loops for
regulation of axial growth are highly nonlinear and act most
efficiently on the myopic side. We found that, subsequent to a
period of binocular deprivation of form vision, the refractive
errors acquired are highly correlated in both eyes. Since both
eyes grew without visual feedback we conclude that the gains in
the feedback loops that control axial growth must be similar in
both eyes.

We suggest that the gains are genetically determined and are
typical for each individual. Chicks made near-sighted in both
eyes by "deprivation of form vision" were corrected by appropriate
negative lenses. Three out of five chicks recovered from myopia
despite the correction. Also two chicks that were made
near-sighted in one eye recovered with no regard to the correcting
lens.

Three chicks remained more myopic than the correcting lens
required and finally started to recover while the lens was still
in place. Two out of three chicks that were made far-sighted
showed recovery despite appropriate correction by positive lenses.

We conclude that there must be a nonvisual mechanism highly
sensitive to abnormal eye shape. During expt (4) we found
unexpectedly that the development of form deprivation myopia is
inhibited if no part of the retina in an animal is exposed to
normal visual experience. The result indicates that some
communication between both eyes exists, although form deprivation
myopia itself has been shown to develop independently in both
eyes.

_______________


Now I do not know how to resolve the above contradictory
reports.

The first report is clean. The second report has a
great deal of convoluted language used to describe something
that should be simple to prove. For that reason I would suggest
using very basic words, i.e., refractive status, and talk about
ONLY what you measure and what you control

If we can not get a basic concept of measurement correct --
that is very simple -- then God help us with more complex
measurement situations.

As long as this "conflict" exists, then both the "second
opinion" and "majority opinions" are valid.

But the individual still has the right to be informed of this
conflict -- and the right to choose between these contradictory
methods.

We all agree that what ever the choice, the plus must be used
BEFORE the minus lens is used, and that if you begin wearing a
minus lens you will not be able to get out of it at some later
date.

Best,

Otis Brown

 

I don't think scientists will agree with you. Science relies on many
experimenters repeating the same experiment, if the results are replicated
then the results go into the knowledge base, if the results are not
replicated then the results are less likely to be believed.

snip

No one disagrees that the eye is dynamic, we call it accommodation. No one
disagrees that emmetropization exists and works in young human children. We
do disagree that refractive error in adults can be modified by manipulating
accommodation.

Animal studies can be used to make predictions about how the human eye will
work, however, the animal studies should be about the aspect of the human
eye that you want to make predictions about. Experiments can then be done
to test the predictions. Animal studies about emmetropization and
congenital refractive error are abundant. Animal studies about correcting
developmental refractive error are rare. You have used emmetropization
studies using neonatal animals to make predictions about developmental
refractive error in non neo natal humans.

Human data confirms the existence of an emmetropization mechanism in young
humans, similar to the one in young animals. Human trials with humans over
age six have not confirmed the predictions you make from animal studies that
controlling accommodation will prevent myopia. I do not reject the animal
studies out of hand, I reject them because the predictions drawn from them
are not borne out by human trials; the animal studies are not a model for
human eyes.

snip

The first is "clean" because you summarized it in language you like to use.
I used the abstract written by the scientists, if you don't like it complain
to Drs Schaeffel and Howland.

There is no contradiction to resolve in the two studies. The two studies are
about different things: the first is about the emmetropization mechanism
that corrects congenital refractive error. The second is about using
corrective lenses for refractive error that is not congenital. Since they
are about different things, they can have different results. The second
study is about what optometrists do: use the correct lens for existing
refractive error. The first study is about what optometrists do not do: use
very strong lenses on eyes without refractive error.

The first study used high minus and plus lenses on animals without
refractive error to create artificial congenital hyperopia (using minus
lenses) or artificial congenital myopia (using plus lenses) and a control
group with no lenses as emmetropes. The experiment shows the existence of
a emmetropization process: the artifical hyperopes became more myopic and
the artificial myopes became hyperopic so that the net refractive error for
the eye/lens system was zero. Other experiments of this nature have shown
that if the high plus or high minus lens is removed, the eyes will
"recover", ie the myopes and hyperopes both become emmetropic again.

The second experiment used form deprivation instead of minus lenses to make
eyes myopic (a neo natal chick eye will become myopic in the absence of form
vision) and plus lenses to make eyes hyperopic. The animals were then
corrected with the correct amount of minus or plus for the induced
refractive error. Some of the animals maintained the refractive error with
correction (did not get worse) while others actually become emmetropic
despite wearing the correction.

If you still think the language is too hard to understand, here is a
concrete summary.

Some chicks with no refractive error are forced to wear +10 lenses and under
the lens the eye became +8. Some chicks with no refractive error are forced
to wear -10 lenses and under the lens the eye became-8. Some chicks with
no refractive error are given translucent occluders to deprive them of form
vision and became -10 myopes. The +8 chicks were then given +8 lenses and
66% of them end up with zero refractive error, the other 33% stay at +8.
The -10 myopic chicks then wear -10 lenses. About 66% of them also end up
with no refractive error and the rest stay at or slightly less than -10. No
animals increase in myopia while wearing the correct minus lens.

This statement contradicts the animal studies you quoted which you think are
relevant to humans. If the human eye behaves like the animal eye, then you
don't need to use the plus lens at all. The eye will recover from myopia
whether a minus lens, plus lens or no lens is used.

And yet...... myopes exist. Hmmm, maybe the animal studies are not
relevant to humans.

Dr Judy