Converting "Script" to pure Spherical Equivalent

Discussion in 'Optometry Archives' started by otisbrown, Apr 26, 2007.

  1. otisbrown

    otisbrown Guest

    Converting a prescription to the power I would need in a regular lens
    or if someone could
    figure it out I would greatly appreciate it.

    "Sphere", Astigmatism

    Left sph -.50 cyl -.75 ax 170

    Right sph -.75 cyl -.75 ax 170

    To convert take 1/2 the astigmatic part
    and add it to "sph"

    for the Left, then

    -0.75 / 2 = -0.375

    -0.5 -0.375 = -0.875, Spherical Equivalent

    You can round this off to -1.0 diopters.

    You prescription is weak, with you
    Snellen about 20/30 to 20/40.

    You can check with your OD to see
    if this meets your needs.

    otisbrown, Apr 26, 2007
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  2. otisbrown

    p.clarkii Guest

    you can also round it down to -0.75.

    are you trying to overminus everyone?

    why do you keep posting here? you have no academic or practical
    training in this subject yet you keep posting and even arguing against
    people who are orders-of-magnitude more credible than you.
    p.clarkii, Apr 27, 2007
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  3. otisbrown

    otisbrown Guest

    Also, you can "round-down" to -1/2 diopters.

    If fact, you might be over-prescribed to a certain extent.

    You could check a Snellen and determine your
    actual visual acuity.

    In fact, during your exam you might have developed
    muscle-spasm myopia, which I am told gradually
    reduces over time.

    otisbrown, Apr 27, 2007
  4. otisbrown

    otisbrown Guest

    In fact, with a prescription that is almost "plano", you might
    find that your vision has cleared from the last prescription.

    To check, just click on:

    And then click on "Display", and read the chart.

    Your vision might be better than your "prescription" might

    Always good to double check these measurements.
    otisbrown, Apr 27, 2007
  5. otisbrown

    p.clarkii Guest

    indeed! anything that you say that has any ring of validity to it
    would have to be something you have been told since your training is
    nil and your experience is even worse. go away old troll.
    p.clarkii, Apr 27, 2007
  6. otisbrown

    odtobe Guest

    Why would you give this persone the SE? They are not a very good
    candidate. The cyl power is equal to or greater than the sphere power!
    They will most likely not like this RX. Also with such little cyl why
    not Rx it? Edge thickness will not be a problem, and the tolorances
    for detectable axis change on this little amount of cyl are rather
    large, maening even if you get the cyl axis within about 15-20 degrees
    they will be seeing much better than with the spherical eqiv.
    odtobe, Apr 27, 2007
  7. otisbrown

    otisbrown Guest

    Dear OD-to-Be,

    The person asked for an equation to "simplify" a prescription
    contaning both a spherical component, as well as an
    astigmatic component.

    I provided the correct equation. The person herself must
    decide whether she prefers a -1/2 diopter contact, or
    a -1.0 diopter contact, or no contact at all, since
    her Snellen (naked eye) would be about 20/40.

    For most purposes (except for driving a car) she could
    most likely work with no minus lens at all.

    The information is provided. The choice is hers. If she
    wishes -- she will follow your advice.

    otisbrown, Apr 28, 2007
  8. otisbrown

    Neil Brooks Guest

    Speaking of providing information ...

    Why not provide the information about how you turned your niece into a
    myope with a restricted driver's license?

    As I always say: you can't have it both ways. If you claim to have
    CAUSED your nephew, Keith's, emmetropia then you must also claim to
    have CAUSED your niece's myopia.

    Full information really IS a good thing, isn't it?
    Neil Brooks, Apr 28, 2007
  9. otisbrown

    odtobe Guest

    I'm sorry Otis you're right, information is free and good to give the
    patient. But I was under the impression that a DOCTOR has a liscense
    to practice medicine. Shouldn't doctors be in the habit of providing
    solutions that are going to be the most benifetial to the patient?
    Also this person is a rather poor CL candidate, at least for softs.
    Might think about RGPs if the K's look correct, but the SE for a spec
    lens just doesn't make any sense. They have already chosen the
    cylinder lenses in the "SUBJECTIVE" portion of the refration, that's
    generally how an RX is finally determined. I understand that giving a
    person the SE in a sphere SCL would be nice, BUT NOT IN THIS CASE.
    odtobe, Apr 29, 2007
  10. otisbrown

    p.clarkii Guest

    yes indeed otis! I agree whole-heartedly. if you try to stand-up and
    lay claim to Keith as being an example of "plus prevention" then you
    must also stand-up and provide an explanation of why is DIDN'T work
    for your niece who became myopic despite your treatment! the reason
    for your niece's failure is that refractive outcomes are not affected
    in the least by using plus lenses. that result has been proven in
    multiple scientific studies which you seem to ignor. i'm sure you'll
    think of some kind of bullcrap excuse, or perhaps you'll just refuse
    to address the question like you always do when you are proven wrong.
    a real scientist wouldn't do that, and indeed an honest objective
    person of any professional background wouldn't do that-- but Otis
    Brown does. that speaks volumes about your character.
    hello odtobe! perhaps you are not familiar with our resident troll
    Otis Brown, engineer.

    Otis believes he is an expert in physiological optics and
    myopiagenesis even though he has no training, research, or clinical
    experience in the topic. he claims that he has gained insight into
    these topics because of a life-long involvement in the field which
    includes friendships with many experts. in fact, when you check up on
    his claims by talking to some of these so called "friends", like Dr.
    Ted Grosvenor, they have never heard of Otis Brown and furthermore
    they do not believe in any of the outdated concepts that Otis adheres
    to. curious, is it? Otis likes to name-drop. perhaps once these
    experts studied the possibility that plus lenses might reduce
    accommodative strain and minimize myopia development, or that
    excessive minus lens prescriptions might increase myopia, but being
    objective men of science they have discarded that theory because it
    was disproven decades ago. But Otis is stuck in the past and will not
    accept the pile of research data that clearly demonstrates that myopia
    development is a little more involved than his simple-minded scheme.

    And when you confront Otis with straight-out scientific proof that his
    theory is wrong he ignors you or either he instead offers an anecdotal
    story about "Mike" or "Jane" or some such other person he has talked
    to that relays a personal story that for some reason he holds in
    higher esteem to real objective scientic studies. in the past, one of
    his so-called personal success stories actually saw what he was
    writing and confronted Otis on this newsgroup. He relayed that Otis
    was misrepresenting his personal experience as proof that plus lens
    therapy actually worked in his case when in fact the opposite was
    really true-- his myopia persisted.

    yet still, despite public humiliation, otis fights on. he is nothing
    if not persistent. he tries to describe a difference between
    "medical" scientific studies and "engineering" scientific studies that
    is puzzling and ridiculous.

    as clueless as Otis is he is actually a kind of fixture around this
    newsgroup. don't try to reason with him-- his mind is made up and he
    doesn't want to be confused by the facts.
    actually I am not in complete agreement with this statement. many
    patients with this low level of astigmatism don't really notice a
    significant improvement in their VA when you correct their
    astigmatism. the patient may achieve 20/20- with a spherical
    correction and get only a slight boost from additionally correcting
    the cylinder component. sometimes that boost is visually insignificant
    to the patient. -0.75 cyl just isn't that much.

    and it is obvious that RGPs are going to be less successful than
    disposable SCL. not due to any optical considerations but due to the
    fact that 80-90% of patients who first put in an RGP and not happy
    with the comfort of the lens regardless of whether they can see a
    sharp image or not. trying to fit such a patient in an RGP is a good
    way to ensure that the patient will not return to your office for
    their next appointment, or for any appointments, in the future.

    in this case I would usually give the patient a trial pair (disposable
    SCL) of spherical lenses and a trial pair of toric lenses and ask them
    to compare them at home for approximately a week and then return to my
    office for a check appointment wearing their favorite pair.

    this is just my way of doing it, and what my personal experiences are.

    p.clarkii, Apr 30, 2007
  11. otisbrown

    otisbrown Guest

    Dear Majority-opinion PClar,
    RESPECT the second-opinion regarding the minus.

    I understand how EASY it is to impress a person with it.

    Be equally, avoiding the minus has a long history.

    Here is a recommendation by Dr. David Guyton,
    about avoiding the use of the minus:

    "For my young patients with simple myopia, I suggest they
    leave their distance glasses off while reading, something I have
    always done myself. A child who cannot see the board at school,
    for example, should wear glasses to see the board, but remove them
    when reading a book or writing."

    You keep on insisting that the minus "is perfectly safe", and
    that is your OPINION. I happen to disagree with your OPINION.

    You tell me that a -3 diopter lens has NO EFFECT on the
    refractive STATE of the fundamental eye. I take your
    word -- but I run the scientific test.

    In fact, when you place a -3 diopter lens on the eye, it will
    respond by changing its refractive STATE by an averge
    of -2 diopters in less than six months.

    So the subject remain a matter of your BELIEF that a population
    of natural eyes are NOT DYNAMIC, and the minus is "perfectly safe".

    Sorry you are disconnected from the second opinion regarding
    the proven behavior of the natural eye.

    otisbrown, Apr 30, 2007
  12. otisbrown

    otisbrown Guest

    Here are the scientific facts, RESPECTING the natural
    eye as a dynamic system:

    I am certain you will invent "stories" to "explain away" these
    direct scientific facts, to justify your majority-opinion.

    But that is exactly why there is a honest second opinion
    stated at:

    Scientific honesty would perhaps help the parents
    understand the necessity of insisting that their children
    keep their NOSE off that page. That would be
    the first step in a PREVENTIVE program.

    But I truly admit how difficult it is to PRY a child's
    nose off that page. In fact he induces this negative
    refractive STATE by actions of that nature.


    otisbrown, Apr 30, 2007
  13. otisbrown

    Ms.Brainy Guest

    Otis Dear,

    I don't subscribe to the notion that anecdotal "evidence" as a
    scientific proof, but since you do, here is one:

    I got my first eyeglasses when I was 13. They were -1.5D for each
    eye. I did not use them full time, only when I needed to see afar. I
    read and did my homework without glasses. My myopia was not cured,
    and in fact increased. Eventually I wore them almost full time. I
    had a friend with a similar condition, although she resisted her
    glasses longer than me (for vanity reasons). Would you suggest that
    both I and my friend were mutants and the exception to your theory? I
    must admit that I never used the "plus" because I could read fine
    without glasses.

    You ignored my previous response to your messages, perhaps you can
    respond to this one?
    Ms.Brainy, Apr 30, 2007
  14. otisbrown

    Neil Brooks Guest

    Ms. Brainy:

    Otis doesn't ever respond to direct questions, particularly those that
    area legitimate, relevant, coherent, or threaten to highlight his
    idiocy ... like yours.

    As you were....
    Neil Brooks, Apr 30, 2007
  15. otisbrown

    odtobe Guest

    p.clar thanks for the update. I have read some of Otis' post in the
    past, but never had a direct confrontation with him. Thanks for
    bringing me up to speed. I would have to agree with you regarding
    RGPs :), but you can't altogether discount them as a posibillity
    dispite poor first impressions. However, you are probably correct in
    that RGPs are considered after SCLs. But hey, I'm still a student, we
    are a little more optomistic in the educational rhelm.

    odtobe, Apr 30, 2007
  16. otisbrown

    p.clarkii Guest

    really? please tell me about the scientific test that you ran. you
    said that you ran it so tell me how you set it up and tell me the

    I don't want to hear you rehash an old scientific study run by
    somebody else on lenses sutured full-time to a monkeys eye (which by
    the way is animal cruelty). I want to hear about tests YOU ran (just
    like you said) on humans. Excessive minus lenses HAVE been applies to
    human eyes and found to have no effect. Its published. Please tell
    us YOUR results.

    I know what is dynamic about the human eye. You don't.
    One thing is for sure-- your brain is not dynamic. you are unable to
    read scientific studies and understand their consequences and
    really? what is proven about the human eye that supports your opinion
    (not called the second opinion, but really Otis' personal opinion)?
    p.clarkii, Apr 30, 2007
  17. otisbrown

    p.clarkii Guest

    Otis-- where are you?
    Why do you always disappear when its time to answer the hard
    Tell us about your results. No anecdotal stories, or quotes from
    famous researchers whom you claim to know but really don't. No
    putting words in anyone's mouth about "box camera model" or "static
    eye" blah blah blah. Just tell us the results of your study which
    shows that -3 diopter lenses cause humans to develop myopia.
    What journal have you submitted it to?
    .. . . . . .
    .. . . . . .
    ah . . . Otis? ... are you there?
    p.clarkii, May 1, 2007
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