school myopia

Discussion in 'Optometry Archives' started by William Stacy, Apr 13, 2005.

  1. Andrew:

    I read most of the "school myopia" piece, and appreciate your sending
    it. Quite an exhaustive review of the literature on the subject. One
    thing that stood out was the prevalence of myopia in Taiwan. The 80%+
    numbers would seem to support my argument that low to moderate levels of
    myopia a really a normal adaptation to the near point environment. It's
    natures way of allowing close focused folks to maintain clarity at the
    near point throughout their lifetimes naturally.

    w.stacy, o.d.
     
    William Stacy, Apr 13, 2005
    #1
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  2. William Stacy

    Dr. Leukoma Guest

    I gather you are referring to the study published in Investigative
    Ophthalmology and Visual Science 2005 Jan;46(1):51-7 by Saw, Tong, Chua
    et.al. of the Department of Community, Occupational and Family
    Medicine, National University of Singapore.

    The points I found most interesting were:

    ---------------------------------------------------------------------
    The 3-year cumulative incidence rates of myopia were higher in Chinese
    (49.5% vs. 27.2%) and in 7-year-old compared with 9-year-old children
    at baseline (47.7% vs. 32.4%), though the latter relationship was of
    borderline significance after adjustment for race, gender, amount of
    reading (books/week), and parental myopia (P=0.057). Premyopic children
    with greater axial lengths, vitreous chamber depths, and thinner lenses
    were more prone to the development of myopia, after controlling for
    age, gender, race, reading, and parental myopia.
    -----------------------------------------------------------------

    I'm not sure how Andrew will explain away an environmental basis for a
    premyopic structural/anatomical risk factor for the development of
    myopia, but I suspect that a doozy of an attempt will be made. No
    doubt the word "sugar" will figure into it.

    DrG
     
    Dr. Leukoma, Apr 13, 2005
    #2
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  3. I love the term "borderline significant":

    I maintain my own personal tongue in cheek dictionary of scientific terms:

    borderline significant: not significant

    qualitatively similar: quantitatively different

    typical (in the context of "figure shows typical data"): the very best I
    could find

    ....

    Scott
     
    Scott Seidman, Apr 13, 2005
    #3
  4. Actually it was "How genetic is school myopia?" by Ian Morgan and
    Kathryn Rose.

    w.stacy, o.d.
     
    William Stacy, Apr 13, 2005
    #4
  5. William Stacy

    otisbrown Guest

    For Andrew and William,

    Actually the percentage of "myopes" is higher. So
    I guess William is correct. The natural eye will
    "adapt" by changing it refractive state (as a natural
    process, if you place it in a long-term "confined"
    visual enviroment.

    Best,

    Otis

    ________


    MYOPIA PREVALENCE IS ALWAYS HIGHER THAN 90 PERCENT
    FOR TAIWAN MEDICAL STUDENTS


    Re: Changes in ocular refraction and its components
    among medical students - a 5-year longitudinal study", Optom.
    Vis. Sci., 73:495-498, 1996) found that in a study of 345
    National Taiwan University medical students, the myopia
    prevalence increased from 92.8% to 95.8%! over the five year
    period.
     
    otisbrown, Apr 13, 2005
    #5
  6. William Stacy

    g.gatti Guest

    This william stacy is something.

    He has great degrees in learning but comes off with very stupid and
    ubelieving answers.

    The same old rotten answers given since hundreds of years.

    What is your way to cure myopia?

    Be serious!
     
    g.gatti, Apr 13, 2005
    #6
  7. DRG wrote
    with greater axial lengths, vitreous chamber depths, and thinner lenses

    were more prone to the development of myopia, after controlling for
    age, gender, race, reading, and parental myopia.

    Bare in mind Scotts comments. Then take a look at a graph of the
    scatter and then see what 'prone' means.

    I can accept that if you are genetically predisposed to a combination
    of factors that make it more likely for you to get myopia, because the
    emmetropization factor has to work harder (and could if conditions in
    your life were ideal) that you will be more likely (prone) to get
    myopia.

    However if you remove the conditions that alter emmetropization you
    will not get myopia.

    At the end of the say genetic factors are there but environment is more
    influential.
     
    andrewedwardjudd, Apr 13, 2005
    #7
  8. William wrote
    myopia a really a normal adaptation to the near point environment.

    Millions are being spent on myopia research in chinese asians
    countries. No single factor has yet stood out as being the cause of
    myopia.
     
    andrewedwardjudd, Apr 13, 2005
    #8
  9. "No single factor"? Why are you unwilling to settle for less than a
    single causative factor? If they are spending millions in asia to find
    "THE" answer, that's fine, let 'em spend away. It's pretty obvious from
    the literature that it's at least partly the increased demands of modern
    near point stress that's triggering it in susceptible individuals. It's
    like spending millions to find out why people are getting taller, or why
    they are living longer. The causes are similarly complex and not
    answerable by a single factor, but they are pretty well, almost
    intuitively, understood.

    Maybe a better analogy would be to ask why is Arnold Schwarzenegger so
    muscular? The answer is a complex interaction of excercise, diet and
    genetics, at least. Everyone know that.

    Whatever the cause(s) of mild to moderate myopia, I'm not losing any
    sleep over it/them.

    Sorry to hear that some people are...

    w.stacy, o.d.
     
    William Stacy, Apr 14, 2005
    #9
  10. William Stacey wrote
    the literature that it's at least partly the increased demands of
    modern
    near point stress that's triggering it in susceptible individuals.

    Susceptible individuals?

    You mean "The genes are known you fool! everybody knows its genetic
    you moron. You are so unscientific! Goodbye weirdo!"??

    You know i would be almost depressed but I wrote to a prominant myopia
    researcher the other day and he sent me that school myopia study and
    said
    ..
    "Regarding the twin study dilemma I attach a very recent paper (which I
    feel will have a significant influence on how the research community
    view myopia) by Ian Morgan and Kathryn Rose. In the light of your
    comments I think you will find section 3.5 very interesting."

    Change is hard i guess.

    Andrew
     
    andrewedwardjudd, Apr 14, 2005
    #10
  11. I don't think I meant that, but, whatever...

    night, night...

    w.stacy, o.d.
     
    William Stacy, Apr 14, 2005
    #11
  12. William Stacy

    Dr. Leukoma Guest

    Funny how Andrew focuses like a razor on any review article that he can
    use to support his cause, while he ignores a bonafide scientific study
    that contradicts his assumptions. Let's take the Morgan-Rose study for
    example:
     
    Dr. Leukoma, Apr 14, 2005
    #12
  13. William Stacy

    Dr. Leukoma Guest

    Funny how Andrew focuses like a razor on any review article that he can
    use to support his cause, while he ignores a bonafide scientific study
    that contradicts his assumptions. Let's take the Morgan-Rose study for
    example:
    ------------------------------------------------------------------------
    There is, moreover, little evidence to support the idea that
    individuals or populations differ in their susceptibility to
    environmental risk factors.
    ------------------------------------------------------------------------

    In another study published in the same month and year (Jan 2005), Song,
    Chong, Tua and other researchers from the National University of
    Singapore published a prospective cohort study of 981 children followed
    over a 3 year period. They found that the cumulative incidence rates
    were significantly higher in Chinese children, i.e. 49.5% vs. 27.2%.
    They also found that "premyopic children with greater axial lengths,
    vitreous chamber depths, and thinner lenses were more prone to the
    development of myopia, after controlling for age, gender, race,
    reading, and parental myopia."

    The fact that the incidence of myopia was found to be higher in a
    population group (Chinese) does seem to contradict the statement that
    there is no difference in susceptibility of different populations to
    environmental risk factors. Also, it stands to reason that
    susceptibility to myopia may have an anatomical or physiological
    correlate, and that these anatomical/physiological differences may
    determine the eye's response to reading. The environment serves merely
    to provide the increased exposure to tasks for which the
    structure/physiology of the eye(an inherited characteristic or
    population trait) is ill equipped to handle.

    DrG
     
    Dr. Leukoma, Apr 14, 2005
    #13
  14. William Stacy

    Dan Abel Guest


    I don't know if you're kidding us or not. It's hard to tell on
    newsgroups. It's steroids. He has admitted to using them.
     
    Dan Abel, Apr 14, 2005
    #14
  15. There is, moreover, little evidence to support the idea that
    individuals or populations differ in their susceptibility to
    environmental risk factors.

    Once again i am accused of being unscientific. I ignored this quote?

    At first sight you might argue that we will differ in our suceptibility
    to environmental risk factors. for example if reading is a risk factor
    then we see variation to that risk. But what else varies in the
    environment of the people at risk? Perhaps school stress **and**
    reading are **two** risk factors to which all people would be equally
    effected..

    What the study claims is that there is no evidence that we differ in
    our susceptibility to environmental risk factors. At first site that
    seems nonesense but if we take in all risk factors it makes more sense.
    I am not sure that is a reasonable thing to say but how does this
    make me unscientific?

    Andrew
     
    andrewedwardjudd, Apr 14, 2005
    #15
  16. Drg G wrote
    were significantly higher in Chinese children, i.e. 49.5% vs. 27.2%.
    They also found that "premyopic children with greater axial lengths,
    vitreous chamber depths, and thinner lenses were more prone to the
    development of myopia, after controlling for age, gender, race,
    reading, and parental myopia."

    Well first we need to define what is meant by premyopic children. If
    these children previously had shorter axial lengths and were not
    measured at that point then a myopic pattern of eye growth *may* have
    already started due to factors not identified in the study which have
    nothing to do with genetics.

    However i dont deny that if you do happen to have a combination of
    growth factors that result in myopic growth of the eye then an
    emmetropization process will have to work harder to resolve that. My
    point is that dispite widespread variance in eye component sizes normal
    sight is the norm when environmental influences do not work together to
    create myopia.

    I conclude that identifying precisely the nature of those environmental
    factors would be a useful thing to do. You conclude its pointless
    (Your eskimo comments).

    At this point in time i am unaware that Singapore University have
    concluded on the balance of all of their studies that Chinese children
    in Singapore are genetically more suceptible to getting myopia than any
    other group.

    Do you have a link to this study or ideally the full PDF i can read
    please? i have tried to find it but cannot so far locate it.

    Thanks

    Andrew
     
    andrewedwardjudd, Apr 14, 2005
    #16
  17. Maybe a better analogy would be to ask why is Arnold Schwarzenegger so
    newsgroups. It's steroids. He has admitted to using them.

    Well if steroids are part of your diet then strange things happen.
    Diet alone would not have created Arnold. He did exercise too, and was
    enormously determined to be somebody when he was earlier mr nobody.
    Clearly genetics must play a part there somewhere.

    But take away the steroids and the exercise and you would have mr
    puniverse from Austria.

    Similarly the environmentalists argue that if you take away the complex
    environmental factors at play in myopia then myopia becomes very
    unlikely.
     
    andrewedwardjudd, Apr 14, 2005
    #17
  18. ok i have found it now. It was by Saw not Song.

    Singaporean incidence of myopia is well known.

    Singapore is a tiny island state on the end of the Malay peninsula.
    Population pressure for housing and economic pressures to be
    successful are huge there. Also there is an unusual semi
    authoritarian state structure. Asians countrys generally are big
    on family authority and compliance to it via emotional pressures.
    Similarly some American children call their fathers 'sir'. This kind
    of unyielding respect for authority and obeyance of it are not common
    for example in Australia or Britain where sticking your fingers up to
    the Queen is almost part of life for many people.

    Strange though it might seem, cultural differences and genetic
    differences are very hard to separate out unless you look at how
    cultures differ in aspects of what one might assume are identical
    factors across all cultures. Family life is one of the biggest
    environmental influences we can have. To suggest that ethnic chinese
    live identically to ethnic Malays is a bit of a stretch of the
    imagination.

    Its simplistic to point to genetic differences when complex
    environmental factors are at work.

    If a study shows different ethnics group living in very similar faimily
    and wider environments have similar myopia then I would be inclined to
    be influenced by such a study. What we do know is that myopia seems
    associated with urbanisation. Singapore and Taiwan are similar high
    population centres with high chinese myopia.

    what do we conclude?

    Andrew
     
    andrewedwardjudd, Apr 15, 2005
    #18
  19. I think emmetropization is probably a one way street. That is, a
    normally developing eye can grow its way from hyperopia into emmetropia,
    and then into myopia, but it can't "shrink" its way back from myopia to
    emmetropia, nor, thankfully, from emmetropia back into hyperopia. This
    is intuitive, for sure, but it also just happens to agree with what we
    observe clinically.

    w.stacy, o.d.
     
    William Stacy, Apr 15, 2005
    #19
  20. William Stacy

    Dr. Leukoma Guest


    Indeed, what do we conclude?

    Don't take offense, and I don't say this to be mean because I think
    that you will agree that what we can conclude is that you are full of
    hot air. I literally had a hard time keeping a straight face.

    DrG
     
    Dr. Leukoma, Apr 15, 2005
    #20
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