Inconsistent Medical Study Results

Discussion in 'Optometry Archives' started by Otis Brown, Sep 8, 2004.

  1. Otis Brown

    Otis Brown Guest

    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.



    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

    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.





    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


    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


    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,

    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

    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


    Now I do not know how to resolve the above contradictory

    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

    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


    Otis Brown
    Otis Brown, Sep 8, 2004
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  2. Otis Brown

    Dr Judy Guest

    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.

    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

    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.

    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
    Dr Judy, Sep 9, 2004
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