Technical Analysis as to why the eye goes "down".

Discussion in 'Eye-Care' started by Otis Brown, Aug 12, 2004.

  1. Otis Brown

    Otis Brown Guest

    Dear "Repeating Rifle", (Bill)

    Below is a statement of objective fact concerning
    the behavior of the eye.

    The paper that follows explains why (in mathematical
    format) the eye MUST change with the applied minus lens.

    How much clear can the experimental data become?

    For thoughtful analysis.

    If you kids are wearing a plus for prevention -- keep
    them at it.




    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.


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

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

    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.

    The control group did not change significantly in any direction.


    Paper 29


    By Otis Brown

    Physical concepts are free creations of the human mind, and
    are not, however it may seem -- uniquely determined by the
    external world. In our endeavor to understand reality we are
    somewhat like a man trying to understand the mechanism of a closed
    watch. He sees the face and the moving hands, even hears it
    ticking, but he has no way of opening the case.

    If he is ingenious he may form some picture of the mechanism
    which could be responsible for all the things he observes, but he
    may never be quite sure his picture is the only one which could
    explain his observations.

    He will never be able to compare his picture the real
    mechanism and he cannot even imagine the possibility of the
    meaning of such a comparison.

    Albert Einstein


    In the previous chapter we developed a very accurate equation
    that duplicates the eye's behavior. The eye needs a very high
    level of tracking accuracy; using very basic data, we can estimate
    that the eye tracks its environment with a probable-error of
    better than 0.57 diopters.

    Detailed measurements made by Dr. Francis Young show major
    changes in the optical components of the growing human and primate
    eye. Paradoxically, the eye maintains an over-all focal accuracy
    of better than one percent of its total power. The eye maintains
    this accuracy (relative to its visual environment) even though
    individual optical components are changing in an unpredictable

    Dr. Lawrence Stark's work has demonstrated high level
    accuracy for the accommodation (lens/retina) neurological system.
    This chapter extends his work by developing a perturbation
    (growth) control equation that accurately predicts the eye's
    response to step-change disturbances.


    The lens of the human eye undergoes a focal power change of
    about 20 percent over a period of ten years. Without reference to
    feedback control concepts, a systems engineer will be hard-pressed
    to explain focal accuracies of one percent for the normal eye,
    while major optical components are changing by 20 percent.

    A graph of this focal change, and other optical parameter
    changes have been published by Dr. Francis Young and Dr. George
    A. Leary. (1) (See Figure 1)


    As previously developed, the transfer function for the
    long-term growth of the eye is: (2)

    1/ (TAU s + 1)

    Where: TAU = 100 Days. (The eye's time-constant)

    When a step-function is applied to this transfer function,
    the resulting equation is:

    System's Response = [ Step Input / s ] * [ 1 / (TAU s + 1 ) ]

    The time response of this function is: (3)

    Focus = Offset + Accommodation + Step Input * [1 - EXP ( - t / TAU)]

    If a perturbation occurs within the control loop, it will
    cause not only a step-input to the system, but an immediate
    perturbation in the focal setting of the eye:

    System's Response = [ Perturbation ] * [ 1 / ( TAU s + 1 ) ]

    The standard response for an impulse perturbation is:

    Focus = Offset + Accommodation - Perturbation * EXP ( - t / TAU )


    Let's examine the equation as applied to wild monkey's eyes.

    Perturbation = 0 diopters Offset = +1.5 diopters

    Time = 300 days TAU = 100 Days

    Accommodation (Average) = - 0.9 diopters

    Focus = Offset + Accommodation - Perturbation * EXP ( - t / TAU )

    Focus = 1.5 + ( -0.9 ) - ( 0 ) * EXP ( -300/100 )

    Focus = + 0.6 Diopters

    This result corresponds to +0.577 diopters mean value,
    obtained from measurements of a large number of wild (open-pen)
    monkey's normal eyes.


    Now, consider the eye's response to a - 0.5 diopters change
    in the focal power of the cornea. (This change could be induced
    by use of a - 0.5 diopter contact lens) Prior to the perturbation,
    the focal status was + 0.6 diopters. Immediately after the
    perturbation: (At t = 0 )

    Focus = Offset + Accommodation - Perturbation * EXP ( - t / TAU )

    Focus = 1.5 + (-.9) - (-.5) * EXP ( - 0 / 100 )

    Focus = +1.1 diopters

    After 300 days, the focal status will be:

    Focus = 1.5 + (-.9) - (-.5) * EXP ( - 300 / 100 )

    Focus = + 0.625 or approximately + 0.6 diopters

    The eye's focal control system has returned the eye to the
    focal status that existed before the -0.5 diopter perturbation


    In a similar vein, we can predict the eye's response to a +
    0.5 diopter perturbation. (Simulated by use of a +0.5 diopter
    contact lens.)

    Focus = 1.5 + (-.9) - ( +.5) * EXP ( - 300 / 100 )

    Focus = + 0.575 or approximately + 0.6 diopter

    (If the +0.5 contact lens is now removed, the eye's focal
    status will be +1.0 diopters.)

    Obviously, the human eye is not subject to only a single
    perturbation. We can, nevertheless, deduce the control action of
    the normal eye by studying the response of the eye to such
    idealized disturbances.


    In actual fact, the eye is subject to continuous
    perturbations (noise) while growing. This noise tends to
    randomize the eyes' focal status. The control action of the
    normal eye works to overcome this randomness, exercising control
    over the appropriate optical components (corneal radius, length)
    to ensure accurate focus. A study of monkeys' eyes demonstrates
    that, with a steady state visual environment, their normal eyes
    maintain a focal accuracy of better than 1.0 percent.


    The graph on the following page presents two
    computer-generated statistical distributions for wild, or "open
    pen" monkeys' eyes. The focal status histogram was obtained from
    measurements made by Dr. Young on 375 monkeys. The accommodation
    histogram is the estimated average value of accommodation for all
    the monkeys. Some monkeys will spend more time looking at close
    objects, and will have an average value of accommodation of
    perhaps - 1.2 diopters (and corresponding focal state of + 0.3
    diopters), while other monkeys will spend more time looking at
    distant objects and will have an average value of accommodation of
    perhaps - 0.6 diopters (and a corresponding focal state of + 1.1
    diopters). The preliminary mean value for the 375 monkeys is -0.9
    diopters (producing an over-all focal status of +0.6 diopters.)
    (See Figure 2)


    If the normal primate eye is to achieve a high level of focal
    accuracy in the presence of continuous perturbations, the author
    has concluded that the eye must employ dynamic control to set its
    focus. This chapter presents a high performance model that
    provides a focal control mechanism that is, as far as we can
    determine, consistent with all the physical evidence pertaining to
    the normal eye's behavior.

    The model evolved as a result of a long investigation in
    which many preliminary approaches were discarded because they led
    to inconsistencies. It is clear that the number of approaches
    that can satisfy the evidence is limited. An electrical engineer,
    when faced with similar engineering requirements for focal
    precision, will develop this type of design to meet the accuracy
    requirements of the eye.

    The philosophy of this chapter has been to study the focal
    control process of the normal eye by treating it as a design
    problem. The procedure followed is to develop a system model with
    the focal performance capability comparable to the normal primate

    Measurements on individual optical components of the eye are
    exacting, and it is difficult to say which optical component
    causes a specific problem. The researcher can be aided by an
    engineering approach to this complex system, since the eye is an
    intricate data-processing system. The primary neurological
    process is controlling a dynamic (100 day time-constant) focal
    system on a microscopic level.

    It should be remembered that there are several major optical
    components of focus, any of which can dramatically affect the
    focal state of the normal human eye. While the eye is growing,
    these components are continually changing in value.

    Figure 2

    Histograms for the Average Accommodation Status and the Focal
    Status of the Normal Eye

    .0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0
    -1.5 .0 .2 .
    -1.4 .0 .9 . A
    -1.3 .1 2.7 . A
    -1.2 .1 6.5 . A <---------------<< Accommodation
    -1.1 .2 12.1 .F A
    -1.0 .3 17.6 .F A
    -.9 .4 20.0 . F A<---
    -.8 .6 17.6 . F A V
    -.7 .8 12.1 . F A V
    -.6 1.1 6.5 . F A |
    -.5 1.4 2.7 . F |
    -.4 1.8 .9 . A F |
    -.3 2.3 .2 . F Offset 1.5 Diopters >>-->|
    -.2 2.9 .0 . F |
    -.1 3.4 .0 . F |
    .0 4.0 .0 . F |
    .1 4.6 .0 . F |
    .2 5.1 .0 . F |
    .3 5.6 .0 . F |
    .4 6.0 .0 . F |
    .5 6.2 .0 . F v
    .6 6.3 .0 . F<-------------------
    .7 6.2 .0 . F
    .8 6.0 .0 . F
    .9 5.6 .0 . F
    1.0 5.1 .0 . F
    1.1 4.6 .0 . F
    1.2 4.0 .0 . F
    1.3 3.4 .0 . F<----------------<< Focal Status
    1.4 2.9 .0 . F
    1.5 2.3 .0 . F
    1.6 1.8 .0 . F
    1.7 1.4 .0 . F
    1.8 1.1 .0 . F
    1.9 .8 .0 . F
    2.0 .6 .0 . F
    .0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

    When a physiologist experiments on this complicated data
    processing operation, he is in the same position as a technician
    who is presented with a computer system that determines rocket
    guidance. He is then told to make measurements on the individual
    components of the device until he determines which component
    establishes the tracking accuracy of the system. Actually, the
    physiologist is in a more difficult position because so much of
    the data processing of the eye is at the molecular level, almost
    beyond the reach of his instruments.

    The mathematical systems concepts used in automatic control
    evolved out of necessity, as it became apparent that modern servo
    systems could not be understood by studying the characteristics of
    their individual components. This truth applies just as strongly
    to complex processes encountered in biological-optical systems.
    The electronics engineer can establish a solid mathematical
    foundation for an analysis that will accurately predict the normal
    eye's focal control response.

    The same equation that precisely anticipates the normal eye's
    perturbation control also predicts that nearsightedness can be
    avoided. In addition, the equation can give conceptual and
    practical guidance to a successful nearsightedness avoidance

    There are other more sophisticated means of determining the
    eye's tracking accuracy, and these techniques will be developed in
    the next chapter.


    Accuracy: The eye is about 2.4 cm in length. The eye must have a
    focal power of 57 diopters to focus light on the retina.
    The focal status histogram for normal eyes has a
    standard deviation of .843 diopters, and a probable
    error of .843 X .674 = .568 diopters. We may,
    therefore, specify that the eye has a tracking probable
    error of .568/57 or approximately one percent of its
    total focal power. This is the worst-case value. For a
    number of reasons, we should expect that the tracking
    accuracy of the normal eye will be considerably better
    than one percent. In the next chapter we will provide
    an analysis that demonstrates that the actual tracking
    probable-error is on the order of 1/10 diopters.


    PERSONS (207-225) Progress in Ape Research (1977)

    2. Brown, O., Berger, R. A NEARSIGHTEDNESS COMPUTER (343-346)
    Proceedings of the 7th New England Bioengineering
    Conference (1979)

    GROWTH OF THE EYE Proceedings of the 8th New England
    Bioengineering Conference (1980)
    Otis Brown, Aug 12, 2004
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  2. Otis Brown

    Guest Guest

    BIG SNIP.................................................

    Not based on proven data concerning HUMAN eyes Otis.
    Your usual data of apes and chickens mixed with some humans in the blender.
    The outcome?
    A soup or should I say your usual soap?
    The usual blabla instead of proof by Otis.

    Also writing "by Otis Brown" followed immediately by a text written by
    Albert Einstein is realy weird.

    Jan (normally Dutch spoken)
    Guest, Aug 12, 2004
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  3. Otis Brown

    Otis Brown Guest

    Dear Jan,

    In the original text, each chapter had an italized quote.

    Since this is a basic "text" editor, that was "lost".

    Einsteins statment was to the effect that there is
    no "perfect" representatin of experimental "reality",
    and the the concept of the "pure" eye as exclusively
    a rigid box might be an "idealization" that has
    lost is believeablity.

    What we are arguing about is whether the NATURAL EYE

    This is NOT A DEFECTIVE PROCESS. If you take an
    eye with a refractive status of +1.5 diopter (population
    of this status), and place a minus lens of -1.5 diopter,
    the refractive status will move in a negative direction
    by about 1.0 diopter.

    At the end of this test, this young eye will have
    a refractive status of +0.5 diopters -- AND WILL NOT
    HAVE "failed" anything.

    The point is that this eye behaves "dynamically",
    and you insist that it does not.

    This is indeed a pure-scientific argument, and some
    people with a more "open" intellect will begun
    to understand this type of technical analysis.

    I regret it if you do not.




    Otis Brown, Aug 13, 2004
  4. Otis Brown

    Otis Brown Guest

    Dear Jan,

    OK, I get it.

    The chicken eye goes "down" when you place a minus lens
    on it -- because it is a sophisticated control system.

    1. {Going "down" proves that the natural eye is dynamic.
    I said NOTHING about ANY DEFECT. Only the OBJECTIVE,
    repeatable scientific truth.) Isn't the "repeatable
    experiment the "exemplar" of fundamental science?

    2. Ok, so you agree with me that all chicken eyes
    are dynamic in the above sense -- and do not
    challenge the statement.

    3. Then we study two speciese of primate eye.
    (We must make drastic changes to the "population"
    to see the underlying "control" effect.)
    As per Dr. Francis Young's work to determine
    if the primate eye was "dynamic", i.e., changes
    its REFRACTIVE STATUS as the enviroment had
    an imposted "step change", you again agree
    that the adolescent primate (monkey) eye is
    dyanamic, since Dr. Young was a VERY CAREFUL
    experimeter -- and his experiment can be repeated
    as many times as you like.

    4. But they we come to the human-primate eye, and
    you tell me, that the human eye IS A BOX CAMERA
    that does not change its refractive status
    as the visual environment is changed.

    5. So human eyes are "box-cameras", and all
    other eyes are "dynamic" by direct test.

    Interesting theory you have there, Jan.



    Otis Brown, Aug 13, 2004
  5. Otis Brown

    ry Guest

    <further snip>
    Are you proposing that if you put a minus lens on a hyperopic eye, that it
    will become less hyperopic? I've heard you advocating "plus" for those who
    are myopic, are you also advocating "minus" for those who are hyperopic? And
    if you don't, please explain in the context of your theories why it works
    one way and not the other.
    ry, Aug 13, 2004
  6. Otis Brown

    Guest Guest

    The below shows you do not.
    You are trying to lay words in to my mouth I never spoke.
    As asked before, when you quote, quote correct Otis.
    One big request, do not try to think for me or pretend you can.
    You have a hard time to think even for yourself Otis.
    And proof your idea works on human eyes Otis.
    Guest, Aug 13, 2004
  7. Otis Brown

    Dr Judy Guest


    Of course, Schaeffel was using high power lenses to simulate congenital
    refractive error in chicks with no refractive error. He was studying how
    chick eyes recover from congenital error.

    Here is a study that used minus lenses of the correct power to correct
    myopia. In this study, myopia did not increase in response to the use of a
    minus lens.

    Optical correction of form deprivation myopia inhibits refractive recovery
    in chick eyes with intact or sectioned optic nerves.
    Wildsoet CF, Schmid KL.
    School of Optometry, University of California, 94720-2020, Berkeley, CA,

    Chicks eyes with experimentally induced myopia will change back to
    emmetropia when the myopia inducing treatment was removed. In this
    experiment, experimentally induced myopia was fully corrected or
    undercorrected with minus lenses. Chick eyes stabilized their myopia at a
    level consistent with the correcting lens power used, myopia did not
    progress with use of correcting lens.

    Dr Judy
    Dr Judy, Aug 14, 2004
  8. Otis Brown

    Otis Brown Guest

    Dear Ry,

    I am not proposing that we place a -1.5 diopter lens
    on the natural eye with normal refractive states.

    To prove the point I would place a -1.5 diopter
    on a selected population of normal primate
    eyes, where they were selected to have
    a refractive staus of between +1.0 and +2.0 diopters.

    The normal primate eye, in the wild, or in an
    "open pen" environment have refractive status
    from zero to +2.0 diopters.

    Thus the theory of Jan it:

    Refractive status = Heredity

    Which means there must be no change in
    refractive status between the +1.5 diopter
    primates. If the predictions of his theory is
    correct then

    Test Group (-1.5 diopters = Control Group (no change in
    visual environment

    I predict that the test group will change according
    by about -1.0 diopters in about three months.

    Since an eye with a positive refractive status is
    normal under these circumstances, and both
    groups (if human) would have 20/20, it follows
    that we are only comparing the predictions
    of two scientific theories.

    I hope this clarifies the issue.



    Otis Brown, Aug 14, 2004
  9. Otis Brown

    Otis Brown Guest

    Dear Jan,

    Why don't you make a clear and clean statement about
    the effect of the minus lens on the refractive
    status of the natural eye.

    Is you theory that:

    Refractive status = Heredity

    Or do you agree with me that the
    refractive status OF THE NATURAL PRIMATE EYE
    will change (as per the e ^ (-t /Tau) equation.

    Understand that the strictly natural primate eye
    must behave one way or the other.

    Or are you again going ot change the subject
    and evade the quesiton?

    [I am certain you are not going to answer -- because
    if you do, you will get many questions about even
    the "safety" of the minus lens -- which is what
    is in doubt in this discussion.]



    Otis Brown, Aug 14, 2004
  10. Otis Brown

    ry Guest

    Thanks for the response, but no, it doesn't answer my question. I'm not
    particularly interested in your arguement with Jan at the moment. Let me
    restate my question:

    1) Do you believe that placing a "minus 1.5" lens on a eye with a
    "refractive status" of +2.0 will after three months (citing your answer
    below) will move to a "refractive status" of +1.0?
    ry, Aug 14, 2004
  11. Otis Brown

    Otis Brown Guest

    Dear "Ry",

    Some further clarifications:

    I believe that a negative refractive state of the
    eye can be prevented. If a pilot, or highly motivated
    person "catches" the situation, by checking his
    vision at 20/40, I believe he can clear it at
    that point by use of a strong plus lens.

    This is what Dr. Stirling Colgate did
    for himself, and you can read what
    he said (for free) on my site:

    I acknowledge that this type of "motivation" is
    very difficult to inspire in a person and
    most people will "turn off" if you would suggest
    that this type of work is necessary at the
    20/40 level. That truth does not make prevention
    "impossible" but it does make it very difficult indeed.

    Once a person decides to use a minus lens, then I have
    nothing further to say on the subject. I agree that
    you can not get out of it if you choose to even
    "start" with the minus lens.

    To further respond to your questions:

    Otis> > This is NOT A DEFECTIVE PROCESS. If you take an
    Otis> > At the end of this test, this young eye will have
    I would not use the word "hyperopic" because the requirement
    for perfect vision at the Naval Academy describes the
    eye as having 20/20 and refractive states from between
    zero to +1.5 dipoters.

    I've heard you advocating "plus" for those who
    Otis> Not the case. I advocate that a person
    learn to use the plus BEFORE he fails the 20/40 line
    on the eye chart. As such, the person is not the
    threshold. It depends on whether you call 20/40 vision
    "myopic" or not. Clearly I believe that a highly
    motivated person can clear his vision from
    -1/2 diopter (20/40) to 20/20 (> 0.0 diopters)
    in about 6 months of hard, consistent use of
    a +2.5 diopter lens -- for all close work.

    are you also advocating "minus" for those who are hyperopic?

    Emmetropia is a refractive state of 0.0 diopters. As such,
    essentially eyes with 20/20 are almost all "hyperopic",
    as described by the Naval Academy acceptance criteria.
    I reject the work "hyperopia" to describe the absoluty
    natural and normal eye. It gives a very false idea
    about the natural eye.

    In order to do that it would be necessary to go into detail concerning
    a mathematical model of accommodation. I could do this,
    but it would take some time.

    Just say that, the accommodation system can "track"
    a negative "delta" in accommodation in a "linear" manner,
    and therfore it is easier to demonstrate a forced negative
    change, rather than a "positive change".

    But positive change (from 20/40 to 20/20) is possible - given
    that the person has great personal resolve to "work" the
    issue properly.

    I have proposed a study of that type -- but the issue
    remains to be resolved.


    Otis Brown, Aug 14, 2004
  12. Otis Brown

    Guest Guest

    Why don't you show proof Otis, your idea about the plus lens works?
    Further, do not speak on my behalve, quote correct and if you can't, do not
    try to show text I never wrote (examples again below).
    Several times people have shown your idea about preventing myopia is, in
    general, useless.
    You are, untill now, not capable to prove your idea of preventing myopia
    works in human eyes.
    Untill you prove I would say you are the loser.
    An example of your bad habit in not correct quoting, not a text I wrote.
    Nice try Otis, I want to speak about human eyes, you stick to the eyes of
    apes and chickens.
    Understand that YOU must prove it does in human eyes.
    Untill now you are the one who is avoiding giving answers or proof.
    Lots of explainations are already send in your direction but your receiver
    must be out of order.
    You are the one in doubts, I have none in prescribing when necessary.
    IMHO we are not having a discussion, I simple asked for proof your idea
    about preventing myopia works.
    You NEVER show such Otis.

    Free to Marcus Porcius Cato: "censeo Carthagnem esse delendam''

    I declare that Otis idea about preventing myopia in humans must be proved by
    Otis himself or destroyed.

    Jan (normally Dutch spoken)
    Guest, Aug 14, 2004
  13. Otis Brown

    Guest Guest

    Good question Ry.

    Otis however, gives no direct answers on direct questions.

    Jan (normally Dutch spoken)
    Guest, Aug 14, 2004
  14. Otis Brown

    A Lieberman Guest


    Please provide a link supporting your statement to the above AS DESCRIBED
    by the Naval Acadamey ACCEPTENCE CRITERIA?????

    Bet you can't!

    A Lieberman, Aug 15, 2004
  15. Otis Brown

    Otis Brown Guest

    Otis> Assuming an adolescent eye, then yes, I would expect
    that will be the result.

    Otis> I do suggest using a "test group" and a "control group"
    for this test, consisting of at least 10 individuals in
    each group.

    Jan judges that I do not provide "direct answers", so you
    decide. I would place a wager on the outcome of that
    type of experiment. I wonder if Jon would?


    Otis Brown, Aug 15, 2004
  16. Otis Brown

    Guest Guest

    Perfect Otis, the frase ''I would expect''.
    No proof to show Otis?
    Suggest the experiment to your advisor's childs Otis.
    I have no doubts about the type of answering of this OD.

    Free to Marcus Porcius Cato: "censeo Carthagnem esse delendam''

    I declare that Otis idea about preventing myopia in humans must be proved by
    Otis himself or destroyed.

    Jan (normally Dutch spoken)
    Guest, Aug 15, 2004
  17. Otis Brown

    ry Guest

    My comments are below.

    As long as the parameters of the person's eyesight remain within your
    limits, couldn't they use your methods?
    True enough, that's a small amount of hyperopia. Can this same methodology
    be used on a eye with a "refractive status" of +2.5? +3.5?
    Call it whatever you want. If the "refractive status" of an eye is -x, it is
    generally called myopic. If the "refractive status" is +x, it is generally
    called hyperopic.
    As I would define someone at -0.5 as myopic, I take the answer to be "yes I
    advocate plus, for the very mildly myopic." And could this method be used
    for someone at -1.0?
    The term "hyperopia" is just that, a term. Call it a "positive refractive
    status" if you like. The point is, there are some individuals with a
    "positive refractive status" that makes them 20/40 on a Snellen chart. Let's
    say that is +2.25 for the sake of discussion. Would you advocate putting a
    "minus" lens on their eye so they could move their "refractive status" to
    +1.25 and thus pass the Snellen?
    I understand what you're saying, but it seems a convient out. If someone
    fails, they lacked sufficient "resolve".
    ry, Aug 16, 2004
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