The Variability of the Refraction of the Eye

Discussion in 'Eye-Care' started by Zetsu, Apr 21, 2008.

  1. Zetsu

    Zetsu Guest

    [...The Variability of the Refraction of the Eye

    The theory that errors of refraction are due to permanent deformations
    of the eyeball leads naturally to the conclusion, not only that errors
    of refraction are permanent states, but that normal refraction is also
    a continuous condition. As this theory is almost universally accepted
    as a fact, therefore, it is not surprising to find that the normal eye
    is generally regarded as a perfect machine which is always in good
    working order. No matter whether the object regarded is strange or
    familiar, whether the light is good or imperfect, whether the
    surroundings are pleasant or disagreeable, even under conditions of
    nerve strain or bodily disease, the normal eye is expected to have
    normal refraction and normal sight all the time. It is true that the
    facts do not harmonize with this view, but they are conveniently
    attributed to the perversity of the ciliary muscle. This muscle is
    believed to control the shape of the lens, and is credited with a
    capacity for interfering with the refraction in some very curious
    ways. In hypermetropia (farsight), it is believed to alter the shape
    of the lens sufficiently to compensate, in whole or in part, for the
    shortness of the eyeball. In myopia, or nearsight, on the contrary, we
    are told that it actually goes out of its way to produce the
    condition, or to make an existing condition worse. In other words, the
    muscle is believed to get into a more or less continuous state of
    contraction, thus keeping the lens continuously in a state of
    convexity, which, according to accepted theories, it ought to assume
    only for vision at the near-point. This theory serves the purpose of
    explaining to the satisfaction of most eve specialists why persons who
    at times appear to have myopia, or hypermetropia, appear at other
    times not to have them. After people have reached the age at which the
    lens is not supposed to change it does not work so well, while in
    astigmatism it is available only to a limited extent even at the
    earlier ages; but these facts are quietly ignored.

    When we understand how the shape of the eyeball;is controlled by the
    external muscles,.and how it responds instantaneously to their action,
    it is easy to see that no refractive state, whether it is normal or
    abnormal, can be permanent. This conclusion is confirmed by the
    retinoscope, and I had observed the facts long before my experiments
    upon the eye muscles of animals, reported in 1915 [1] (to be described
    again in my forthcoming book) had offered a satisfactory explanation
    for them. During thirty years devoted to the study of refraction, I
    have found few people who could maintain perfect sight for more than a
    few minutes at a time, even under the most favorable conditions; and
    often I have seen the refraction change half a dozen times or more in
    a second, the variations ranging all the way from twenty diopters of
    myopia to normal.

    Similarly I have found no eyes with continuous or unchanging errors of
    refraction, all persons with errors of refraction having, at frequent
    intervals during the day and night, moments of normal vision, when
    their myopia, hypermetropia, or astigmatism, wholly disappears. The
    form of the error also changes, myopia even changing into
    hypermetropia and one form of astigmatism into another.

    Of twenty thousand school children examined in one year more than half
    had normal eyes, with sight which was perfect at times; but not one of
    them had perfect sight in each eye at all times of the day. Their
    sight might be good in the morning and imperfect in the afternoon, or
    imperfect in the morning and perfect in the afternoon. Many children
    could read one Snellen test card with perfect sight, while unable to
    see a different one perfectly. Many could also read some letters of
    the alphabet perfectly, while unable to distinguish other letters of
    the same size under similar conditions. The degree of this imperfect
    sight varied within wide limits, from one-third to one-tenth, or less.
    Its duration was also variable. Under some conditions it might
    continue for only a few minutes, or less; under others it might
    prevent the subject from seeing the blackboard for days, weeks, or
    even longer. Frequently all the pupils in a classroom were affected to
    this extent.

    Among babies a similar condition was noted. Most investigators have
    found babies hypermetropic. A few have found them myopic. My own
    observations indicate that the refraction of infants is continually
    changing. One child was examined under atropine on four successive
    days, beginning two hours after birth. A three per cent solution of
    atropine was instilled into both eyes, the pupil was dilated to the
    maximum, and other physiological symptoms of the use of atropine were
    noted. The first examination showed a condition of mixed astigmatism.
    On the second day there was compound hypermetropic astigmatism, and on
    the third, compound myopic astigmatism. [2] On the fourth, one eye was
    normal and the other showed simple myopia. Similar variations were
    noted in many other cases.

    What is true of children and infants is equally true of adults of all
    ages. Persons over seventy years of age have suffered losses of vision
    of variable degree and intensity, and in such cases the retinoscope
    always indicated an error of refraction. A man eighty years old, with
    normal eyes and ordinarily normal sight, had periods of imperfect
    sight which would last from a few minutes to half an hour or longer.
    Retinoscopy at such times always indicated myopia of four diopters or
    more.

    During sleep the refractive condition of the eye is rarely, if ever,
    normal. Persons whose refraction is normal when they are awake will
    produce myopia, hypermetropia and astigmatism when they are asleep,
    or, if they have errors of refraction when they are awake, they will
    be Increased during sleep. This is why people waken in the morning
    with eyes more tired than at any other time, or even with severe
    headaches. When the subject is under ether or chloroform, or
    unconscious from any other cause, errors of refraction are also
    produced or increased.

    When the eye regards an unfamiliar object an error of refraction is
    always produced. Hence the proverbial fatigue caused by viewing
    pictures, or other objects, in a museum. Children with normal eyes who
    can read perfectly small letters a quarter of an inch high at ten feet
    always have trouble in reading strange writing on the blackboard,
    although the letters may be two inches high. A strange map, or any
    map, has the same effect. I have never seen a child, or a teacher, who
    could look at a map at the distance without becoming nearsighted.
    German type has been accused of being responsible for much of the poor
    sight once supposed to be peculiarly a German malady; but if a German
    child attempts to read Roman print, it will at once become temporarily
    myopic. German print, or Greek or Chinese characters, will have the
    same effect on a child, or other person, accustomed to Roman letters.
    Cohn repudiated the idea that German lettering was trying to the eyes
    [3]. On the contrary, he always found it "pleasant, after a long
    reading of the monotonous Roman print, to return to 'our beloved
    German'." Because the German characters were more familiar to him than
    any others he found them restful to his eyes. "Use," as he truly
    observed, "has much to do with the matter." Children learning to read,
    write, draw, or sew, always suffer from defective vision, because of
    the unfamiliarity of the lines or objects with which they are working.

    A sudden exposure to strong light, or rapid or sudden changes of
    light, are likely to produce imperfect sight in the normal eye,
    continuing in some cases for weeks and months.

    Noise is also a frequent cause of defective vision in the normal eye.
    All persons see imperfectly when they hear an unexpected loud noise.
    Familiar sounds do not lower the vision, but unfamiliar ones always
    do. Country children from quiet schools may suffer from defective
    vision for a long time after moving to a noisy city. In school they
    cannot do well with their work, because their sight is impaired. It
    is, of course, a gross injustice for teachers and others to scold,
    punish, or humiliate, such children.

    Under conditions of mental or physical discomfort, such as pain,
    cough, fever, discomfort from heat or cold, depression, anger, or
    anxiety; errors of refraction are always produced in the normal eye,
    or increased in the eye in which they already exist.

    The variability of the refraction of the eye is responsible for many
    otherwise unaccountable accidents. When people are struck down in the
    street by automobiles or trolley cars, it is often due to the fact
    that they,were suffering from temporary loss of sight. Collisions on
    railroads or at sea, disasters in military operations, aviation
    accidents, etc., often occur because some responsible person suffered
    temporary loss of sight.

    ---------------------------------

    [1] Bates: The Cure of Defective Eyesight by Treatment Without
    Glasses, N. Y. Med. Jour., May 8, 1915
    [2] In astigmatism the eye is lopsided. In simple hypermetropic
    astigmatism one principal meridian is normal, and the other, at right
    angles to it, is flatter; hence the eye is farsighted in one curvature
    and normal in another. In simple myopic astigmatism the contrary is
    the case, one principal meridian is normal and the other, at right
    angles to it, more convex, making the refraction normal in one
    curvature and shortsighted in another. In mixed astigmatism one
    principal meridian is too flat, the other too convex. In compound
    hypermetropic astigmatism, both principal meridians are flatter than
    normal, one more so than the other. In compound myopic astigmatism
    both are more convex than normal, one more so than the other.
    [3] Eyes and School-Books, Pop. Sci. Monthly, May, 1881, translated
    from Deutsche Rundscau...]

    - Dr. W. H. Bates, January 1920
     
    Zetsu, Apr 21, 2008
    #1
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  2. Zetsu

    Jan Guest

    Zetsu schreef:

    Major snip in some very old articles (years 1881 till 1915)
    Zetsu schreef:

    By keeping your eyes open and your mouth shut when reading the messages
    in this newsgroup.

    Jan (normally Dutch spoken)
     
    Jan, Apr 21, 2008
    #2
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  3. Zetsu

    Ms.Brainy Guest

    Yeah, you should tell this to the person on the other thread with the
    -30D Rx. I am sure he would be glad to trade his contact lenses for
    palming, sunning and resting.
     
    Ms.Brainy, Apr 21, 2008
    #3
  4. I was told that the children errors "jumps". Is it truth?

    We have agreed that the accomodation is automatically started with
    converging. This is done by parasympathetic nerves. Is it not possible that
    this nerve system works incorrectly?
    S*
     
    Szczepan Bia³ek, Apr 25, 2008
    #4
  5. I wrote "I was told". It was women. The four ODs tell her that her error
    jumps like at children.
    Growing or shrinking must have a beginning. Does myopia start only in
    childhood?
    Drugs work quickly. The same but in longer time do the diet. You have admit
    that if diabetes is cured successfully the myopia decrease.
    You are sceptical about the excercise. Me too. But I am sure that here must
    be some error in nutrition when myopia start. Do you agree?
    S*
     
    Szczepan Bia³ek, Apr 26, 2008
    #5
  6. Zetsu

    Zetsu Guest

    OK ,why does it come back? My understanding of it so far is this: when
    you instill the cycloplegic drops, this freezes the muscle that causes
    excess accomodation so that it is no longer able to change shape. So
    this acts as a 'temporary fix'. But after a while, when the drugs lose
    their effect, why does this tonic accomodation return? Is it like an
    elastic rubber band kind of thing? I mean, when you stretch it and
    then it goes back to normal?
    What's the purpose?
     
    Zetsu, Apr 26, 2008
    #6
  7. Zetsu

    Zetsu Guest

    OK. What causes tonic accomodation?
     
    Zetsu, Apr 26, 2008
    #7
  8. I understand that such error is bigger in the "out of control." state. If
    yes, how much?
    But myopia sometimes disappear. It must have some reason. The same is with
    the start.
    In mainstream literature any suggestion?
    Is there the Josephson's hypothesis: http://www.i-see.org/josephson.html ?
    S*
     
    Szczepan Bia³ek, Apr 26, 2008
    #8
  9. Not the temporary shift. Study shown: "that myopia can get worse, be steady
    or decrease" in long period of time.
    S*
     
    Szczepan Bia³ek, Apr 27, 2008
    #9
  10. Zetsu

    Zetsu Guest

    What causes the parasympathetic overaction?
     
    Zetsu, Apr 27, 2008
    #10
  11. I am here to lern. Lern how to decrease myopia.

    Now I have known how to do it temporary:
    1. " the lens to return to its "normal" shape when blood sugar comes down."
    ,Does it mean that the tonic accomodation decreases when blood sugar comes
    down?
    2. "For good refraction you must relax" . Does it means take a rest?
    If yes, it can allow to take the following conclusions:

    Blood sugar go together with the potassium. After effort the potassium in
    the blood is also higher. So the high tonic accomodation may by caused by
    high potassium (in Na solution a muscle is relaxed but in K solution
    contracted).
    The only remede may be the John Rollo's diet.
    Is it quite foolish?
    S*
     
    Szczepan Bia³ek, Apr 27, 2008
    #11
  12. I subscribed the vision group 3 months ago. I have never heard about Dr
    Bates and the next.
    This is the key aspect. Blurry is nothing wrong but an big discomfort which
    accompany the tonic accomodation is very unpleasant..
    But is unpleasent.
    Not at all is better than "LOTS of tonic accommodation".
    Could you describe this treatment in a few words.
    Sodium has narrow range (in blood) the potassium much wider. For salt loser
    is better to keep low potassium in the diet than very high sodium.
    It will be seen in a short time. I will try it on myself. Cuts on plant
    starch do not kill me.
    Me not. But thanks your real information - who know. Find do not means
    discovere - it may be very old but not commonly approved.
    Up to now I have found the John Rollo, John Schneider and John Bershak. Will
    be the next John?
    S*
     
    Szczepan Bia³ek, Apr 28, 2008
    #12
  13. Too troublesomeli.
    But I base on "Apparently, the act of convergence lengthens the eye". High
    potassium in the blood contracts the external muscles. Sodium relax.
    Step by step. Less of temporary jumps would be nice.
    S*
     
    Szczepan Bia³ek, Apr 28, 2008
    #13
  14. Zetsu

    Zetsu Guest

    What's worse: hypermetropia or myopia?
     
    Zetsu, Apr 28, 2008
    #14
  15. In Turkey it is "apparent":
    http://content.karger.com/ProdukteDB/produkte.asp?Doi=55551
    I try to find a correlation between myopia and diet plus nerve system.
    When error changes during one day.
    S*
     
    Szczepan Bia³ek, Apr 29, 2008
    #15
  16. Occam's razor.
    http://en.wikipedia.org/wiki/Occam's_Razor

    I'm not disagreeing with you that the question lacked a framework.
     
    Pramesh Rutaji, Apr 30, 2008
    #16
  17. Zetsu

    otisbrown Guest

    Dear Pramesh Rutaji.

    Yes, when a scientific concept becomes excessively complex, then a
    "simplifying" assumption can
    help clear the air. For instance, checking the eye for its dynamic
    behavior,
    is easier that claiming that a -3 diopter lens has NO EFFECT on the
    eye's refractive STATE.

    Enjoy,




    OCCAM'S RAZOR.


    Occam's razor (sometimes spelled Ockham's razor) is a principle
    attributed to the 14th-century English logician and Franciscan friar
    William of Ockham. The principle states that the explanation of any
    phenomenon should make as few assumptions as possible, eliminating
    those that make no difference in the observable predictions of the
    explanatory hypothesis or theory. The principle is often expressed in
    Latin as the lex parsimoniae ("law of parsimony" or "law of
    succinctness"): "entia non sunt multiplicanda praeter necessitatem",
    or "entities should not be multiplied beyond necessity".

    This is often paraphrased as "All other things being equal, the
    simplest solution is the best." In other words, when multiple
    competing theories are equal in other respects, the principle
    recommends selecting the theory that introduces the fewest assumptions
    and postulates the fewest entities. It is in this sense that Occam's
    razor is usually understood.

    Originally a tenet of the reductionist philosophy of nominalism, it is
    more often taken today as a heuristic maxim (rule of thumb) that
    advises economy, parsimony, or simplicity, often or especially in
    scientific theories.
     
    otisbrown, Apr 30, 2008
    #17
  18. Zetsu

    Neil Brooks Guest

    So ... why are YOU still a 6.00d myope?

    I mean ... if your theory has any validity, then .....
     
    Neil Brooks, Apr 30, 2008
    #18
  19. Zetsu

    otisbrown Guest

    Dear Parmesh and Mike,

    Mike mentions "Ethnic" difference???

    Occam's statement was a scientific concept. Not about "Ethnic", and
    this bit about "matzoh balls" implies somthing about
    religion. Mike seems to be "lost" in this discussion of
    fundamental SCIENTIFIC CONCEPTS -- and their development.
    Further, Occam it is not even about "medicine" -- in
    any sense of the word.

    Perhaps Mike can explain what he means about
    Occam and his concept about being "Ethnic".

    Enjoy,



    I'm familiar with Sir William. There are huge ethnic differences to
    explain.

    Fried rice and matzoh balls cause myopia. There - that's simple :).


    -MT
     
    otisbrown, Apr 30, 2008
    #19
  20. Zetsu

    otisbrown Guest

    How would William of Ockham explain the high prevalence of myopia
    among
    urban Asians and Hassidic Jews?


    My answer was flippant - fried rice and matzoh.


    Otis> As most of your answers are -- when the questions involved
    fundamental science.

    Otis> Or you always misconstrue the question -- and insult the person
    asking the question. What else is new?

    Enjoy,
     
    otisbrown, Apr 30, 2008
    #20
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