Scientific fact concerning the second opinion (i.e., prevention)

Discussion in 'Optometry Archives' started by Otis Brown, Sep 11, 2003.

  1. Otis Brown

    Otis Brown Guest

    Dear Vision Research Group,


    Subject: Scientific fact (not anecdotal) data concerning
    the dynamic behavior of all natural eyes.

    Question: Where is the scientific experiments that
    demonstrate with finality that the minus lens has no
    effect on the refractive state of the natural eye?


    I was asked to produce evidence that the natural eye changes
    its focal state as per the applied minus lens.

    Here are the SCIENTIFIC proven effect that the minus lens has
    on your eyes. Read it and weep. Or claim that scientific proof
    means nothing. Or insist that these results are not "repeatable".
    Or insist they "do not relate" to anything you are doing. Or come
    up with a series of "rationalizations" as to why you decide to
    ignore all scientific facts that have an unpleasant "ring" to them.


    Best,

    Otis

    _________________________________


    Compensatory changes in eye growth and refraction induced by
    daily wear of soft contact lenses in young marmosets.

    Whatham AR, Judge SJ.

    University Laboratory of Physiology, Parks Road, Oxford OX1
    3PT, UK.


    Several studies have shown that growth of the primate eye
    responds in a compensatory direction to both positive and negative
    spectacle lenses -- eyes grow more slowly and become hyperopic
    (positive focal status) in response to positive lenses, and eyes
    grow more rapidly and become myopic (negative focal status) in
    response to negative lenses. On the other hand, extended wear
    soft contact lenses, whether positively or negatively powered,
    induce hyperopia (positive focal status).


    ______________________


    (Hung & Smith, 1996. Extended-wear, soft, contact lenses
    produce hyperopia in young monkeys.

    Optometry & Vision Science 73, 579-584.).

    We investigated whether responses in a compensatory direction
    occurred to soft contact lenses worn on a daily wear basis (8 h
    per day on an 8:16 h light:dark cycle). Ten infant marmosets
    (8-13 weeks of age) wore a soft contact lens, in one eye only, for
    5-9 weeks.

    Lens powers used were zero (n = 2), +2 D (n = 1), +2 D
    followed after 5 weeks of lens wear by +4 D (n = 1) for 4 weeks,
    +4 D (n = 2), -2 D followed after 5 weeks of lens wear by -4 D (n
    = 2) for 4 weeks, -4 D (n = 2).

    At the end of the lens-wear period the positive lens-wearing
    eyes were more hyperopic (positive focal status) relative to the
    fellow untreated eyes [mean +2.39 Diopters +/- 0.24 Diopters
    (Standard Error)] and the negative lens-wearing eyes were more
    myopic (negative focal status) than the fellow untreated eyes
    [mean -2.48 Diopters +/- 0.91 D (Standard Error)].

    Fellow eyes were unaffected by lens wear [mean final
    refraction +0.45 +/- 0.09 D (SE)].

    Plano lenses (zero lens power) did not affect eye growth in
    either marmoset fitted with plano contact lenses.

    Invest Ophthalmol Vis Sci.

    2003 Jul;44(7):2818-27.
     
    Otis Brown, Sep 11, 2003
    #1
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  2. I got the impression that you did not need convincing even before
    <>'s post. Am I wrong?

    Bill
     
    Repeating Decimal, Sep 11, 2003
    #2
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  3. Otis Brown

    Dr Judy Guest

    How would we know what power of plus lens to use on the infants so as to
    neutralize the myopia they will develop at age 9? Say we picked + 3.00
    since it is the midrange of the 0 to -6.00 myopia found in average myopes.
    This would over correct some myopes who would end up slightly hyperopic and
    undercorrect a portion who would still need -0.50 to -3.00 for distance
    correction. And it would be insufficient for the myopes destined to be
    over -6.00.

    We know that only about 25% of North Americans become myopic. Based on the
    evidence, we would induce the identical amount of hyperopia in all infants,
    even the ones not destined to become myopes. So if we put +3.00 lenses on
    every infant at birth, at adulthood we would have 75% of the population
    wearing +3.00 correction for hyperopia, another 5% to 10% wearing -0.50
    to -3.00 and another small percentage wearing greater than -3.00 instead of
    the current 25% wearing minus lenses.

    Hey, this means something like 85% of adults age 20 to 45 would need glasses
    to correct either hyperopia or myopia instead of only 30% to 35% of that
    population currently. Wow, what a business opportunity of us purveyors of
    spectacles, fitters of contacts and refractive surgeons. Let's do it ---
    if we recommend plus lenses for all newborns we will all get rich.

    Dr Judy
     
    Dr Judy, Sep 11, 2003
    #3
  4. How about positive half lenses? Then you could see the blackboard and your
    book.

    Bill
     
    Repeating Decimal, Sep 12, 2003
    #4
  5. I would think that the armed forces, particularly the Air Force, would be
    very interested in the prevention of myopia and other vision problems. Have
    they carried out any studies on the effects of negative corrective lenses?

    Bill
     
    Repeating Decimal, Sep 12, 2003
    #5
  6. Otis Brown

    Otis Brown Guest

    Dear Mike,

    The last post to this was lost.

    In short, I do not consider and eye with 20/20 and
    a focal status of +1/2 dioter to be "defective" in
    any sense of the word -- and I do not use and
    term the even suggests this concept.

    The medical deparment considered a value of
    20/20 and focal state of +1.0 diopters
    to be so important that they wanted
    to REQUIRE that value on entry.

    You know that focal states (and 20/20) from
    zero to plus 2 diopters are
    completely normal in children.

    The choice of using a plus when a person
    is with 20/20 and focal state of zero
    must be a choice the person makes for
    himself.

    I have no problem at all with
    a person that turns down this
    choice after careful review of
    the objective scientific facts
    concerning the effect the
    minus lens has on the eye.


    Best,

    Otis
    Engineer

    cc: Dr. Steve Leung
     
    Otis Brown, Sep 12, 2003
    #6
  7. Otis Brown

    Dr Judy Guest

    In the lost posts Mike made the point that if we assume neonatal primate
    research has relevance to humans, it means we should put plus lenses on
    newborn humans during their plastic period so as to induce hyperopia which
    would then be cancelled out when they develop myopia after age 9, ( which
    age is after the plastic period when plus lenses can affect refractive
    error).

    I pointed out that we will have trouble deciding how much plus to use as
    different individuals develop different amounts of myopia, but that at least
    +3.00 would be required. I also pointed out that, since only 25% of the
    population gets myopic after age 9 anyway, using plus lenses on every
    infant would induce hyperopia is 75% of the population who would otherwise
    have little to no refractive error. In other words, for every 25 prevented
    myopes we would create 75 +3.00 hyperopes.
    Nor would I consider them defective. However, +3.00 uncorrected hyperopia
    is not comfortable, those persons would have headaches and discomfort
    reading in their teens and twenties and a significant number of them would
    develop an eso strabismus.
    May be normal, but the children with +2.00 will have esophoria, some will
    have eso strabismus and many will not enjoy reading unless they are wearing
    glasses to correct it.
    All the research you have presented to date refers to treating neo natal
    animals with plus, not adults. So the logical conclusion, based on the
    research you have presented, is what Mike suggested: treat all newborn
    human infants with plus lenses to induce hyperopia with the consequences
    reported above.

    Dr Judy
     
    Dr Judy, Sep 12, 2003
    #7
  8. Otis Brown

    drfrank21 Guest


    I believe that R.D. was referring to "half-eyes" and not wearing + lenses
    part-time.

    frank
     
    drfrank21, Sep 12, 2003
    #8
  9. Otis Brown

    Otis Brown Guest

    Dear Decimal,

    Obviously you can not "teach" monkeys to use
    a plus lens properly. (i.e., look down
    through a strong plus for reading
    (when focal status is at -1/2 diopter).

    The effect of doing this properly it to
    move all objects "out to infinity".

    No one can guarantee results, but the
    pilots who have done this WITH GREAT
    PERSISTANCE, verify their
    ability to clear their vision by +1/2 diopter.

    Best,

    Otis
     
    Otis Brown, Sep 13, 2003
    #9
  10. Otis Brown

    Otis Brown Guest

    Dear Dr. Judy,

    Subject: Your profound scientific analysis.

    Thanks for your commentary on using a plus lens on
    infants. I of couse said nothing about that
    subject.

    I only suggested that a building up some "hyperopic
    reserve of perhaps +0.5 diopters (less than 1 percent
    of the total power of the eye) would be a wise step.

    But, for the record I will pass your commentary
    to others for the "level headed" approach you
    have to a basic "second opinion" approach.

    Best,

    Otis

    *******
     
    Otis Brown, Sep 13, 2003
    #10
  11. Otis Brown

    drfrank21 Guest

    I'm just trying to picture monkeys wearing half-eyes. ;)

    frank
     
    drfrank21, Sep 13, 2003
    #11
  12. Otis Brown

    drfrank21 Guest


    I'd be more concerned about causing a refractive amblyopic situation
    in a toddler/infant if the plus lens blur was too strong for worn too
    long rather than inducing a permanent hyperopic situation. But hey,
    Otis wouldn't care-at person wouldn't be myopic.

    frank
     
    drfrank21, Sep 13, 2003
    #12
  13. Otis Brown

    Otis Brown Guest

    Dear Frank,

    I said nothing of the sort.

    But you keep "doing it".

    The discussion was about pilots entering a 4 year college
    with a focal state of zero diopters.

    Nothing beyond that point. They are old
    enough to look at the facts and decide
    the issue themselves. Perhaps that
    is the only way "prevention" will
    ever be achieved.

    Best,

    Otis
     
    Otis Brown, Sep 13, 2003
    #13
  14. Otis Brown

    Otis Brown Guest

    Otis> The discussion was about pilots entering a 4 year collegeMike> But you won't give them all the facts.


    Otis> Who will not give them all the facts?

    I certainly would provide them. This would
    be in the form of a tutorial where BOTH concepts
    of the eye "passive" versus "dynamic" could would
    be presented. No lens would be used.
    The effect of the minus lens on the focal state
    of the natural eye would be discussed.
    Dr. Hayden's thesis and records would be examined
    in an academic setting.
    The number provided by Dr. Hayden was that entering
    midsipmen with 20/20 but a focal status of zero diopters **
    had about a one percent probability of graduating
    witn 20/20 vision (and a focal status of zero).


    ** (measured with trial lens and snellen chart)
    This ideas of Mike, and there background would
    also be presented. In fact, Mike would be
    invited to present his idea that the natural
    eye does not change its focal status when
    the visual environmnet is changed.

    It is always excellent to juxtapose concepts
    of the natural eyes fundamental behavior.

    I am certain that they could choose a course of
    actions that meets their visual requirements
    as pilots.

    Best,


    Otis
    Engineer

    cc: Dr. Steve Leung
    Alfred

    *****
     
    Otis Brown, Sep 14, 2003
    #14
  15. Otis Brown

    Otis Brown Guest

    Very hard. This proposal was made, and the man (I think it
    was an OD, was kicked out of the office.

    They can then use, or not use them as they see fit.

    I would be better if the effort were systematic and organizedhi.

    You could probably get good results (i.e., a difference in
    focal status between the test group and the control group)
    in about seven months -- with engineers and pilots controling
    the study. The results would be judged by the informed
    engineers and scientists controlling the study.
    monkeys farsighted,

    No, what I said was that the natural eye's focal status
    follows the applied lens -- as a control system as
    expected.


    .... so
    I said that, provided the pilot will check his own
    eye chart at -1/2 diopter (20/40) he has the
    POTENTIAL to clear his distant vision to 20/20 -- under
    his own control. Obviously, at the point the judgment
    is by the pilot -- and result judged by the pilot,
    neither myself or an optometrist is going to "control"
    this effort.

    I do state that it is indeed a "difficult" effort, and
    only the most highly motived pilots should attempt it.


    .... and never mind if it
    Obviously the pilots who reaches 20/20 is "just zero" (old
    word "emmetropic". If he stops there (which is most probable
    his is not going to be "hyperopic" as Mike Tyner likes
    to speculated.

    Farsightedness is "normal" and who cares if pilots can
    read?

    As before, the U. S. Naval Academy required 20/20 and
    a positive focal status running between zero to +1.5 diopters.

    What they said was that the person with 20/20 (focal state
    zero -- emmetropic) had little chance of getting out with
    20/20.
    Your study.
    Francis Young and Kenneth Oakleys study showed that
    the kids wearing a "high" bifocal stopped movement
    into myopia. The control group continued
    into myopia at the rate of -1/2 diopter per year.

    I think over 200 children were involved.

    But of couse you select only those studies YOU like.
    If the identical twins do the same reading at the same
    distances then their focal states will be very similar
    indeed.



    Best,

    Otis
     
    Otis Brown, Sep 28, 2003
    #15
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