Toric contact power increments

Discussion in 'Contact Lenses' started by Charles, Apr 5, 2006.

  1. Charles

    Charles Guest

    I'm trying to get into some toric contacts, but I also want to keep my
    current prescription without overcorrecting. I'm looking for -0.5x180
    and -1x180. My eye doc said the minimum possible is -0.75, and just
    surveying online stores it looks like they all go in 0.5 increments, so
    I couldn't hit the -1 either.

    Is there any brand that could hit my Rx exactly? I can only assume
    that most people just over or undercorrect by 0.25 and don't care, but
    I'm pretty sensitive to it. Thanks.

    Charles, Apr 5, 2006
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  2. Charles

    acemanvx Guest

    how myopic are you? If all you have is a bit of astigmastim, I dont see
    why you even need correction. Many people are still 20/20 or 20/25 with
    -1 astigmastim or less.
    acemanvx, Apr 5, 2006
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  3. Charles

    tkopan1 Guest

    Up to -0.75 to -1.00 cyl at axis 180 is ususally ver easily masked by a
    conventional lens. The stronger the myopia or hyperopia, the less
    likely the need for a cyl correction at 180. If your prescription is
    only astigmatism, then it may be necessary to wear those powers.
    Generally, -0.75 cyl s is the lowest power available.

    Dr. Tom
    tkopan1, Apr 5, 2006
  4. Charles

    p.clarkii Guest

    if you can't answer peoples questions then why even bother to respond.
    go away twit.
    p.clarkii, Apr 5, 2006
  5. Charles

    Charles Guest

    Thanks for the replies. I'm basically all astig; my spherical is +0.25
    and PL. I guess there's few enough people like me that there's no

    Charles, Apr 6, 2006
  6. Charles

    Dan Abel Guest

    Depending upon your interest, it might be worth trying whatever your OD
    recommends as best. A pair of .75s sounds attractive to me, because
    then you don't have to worry about getting them mixed up!

    As others have posted, toric contact lens powers aren't always the same
    as glasses astigmatism powers. You'll need to get some, stick them in
    and then get overrefracted to find out what they do to *your* eyes.

    On the other hand, if you are as picky as it sounds like you are, it
    might just not be worth the hassle.
    Dan Abel, Apr 6, 2006
  7. Charles

    acemanvx Guest

    "On the other hand, if you are as picky as it sounds like you are, it
    might just not be worth the hassle."

    thats what I thought. He probably sees 20/20 or 20/25 without
    correction. Toric contacts would cost him money, cause some discomfort,
    blur vision when they rotate, have a small risk of infection, etc. He
    can try but its not gonna make a difference since they wont be the
    right power and with his pescription so low, theres no market for it.
    acemanvx, Apr 6, 2006
  8. People "like you" that love a really accurate correction do best with
    RGP contacts. If you wore a sherical RGP with aspheric peripheral
    curves you could see at least as well as you have ever seen with
    glasses, perhaps even better. I have quite a few patients that have
    ..50 to 1.0 D cylinders who read the 20/10 line with their aspheric RGPs
    doctor_my_eye, Apr 8, 2006
  9. Charles

    Charles Guest

    Can you give me a ballpark price that I'd expect for something like

    Charles, Apr 8, 2006
  10. Charles

    Charles Guest

    Reading about RGP, it sounds like since they are rigid, they can
    reshape the cornea to some extent and "mask" astigmatism without
    actively correcting for it. The one site I read said that up to 3
    diopters can be addressed this way sometimes. Does it ever make sense
    (with a low astigmatism-only Rx) to prescribe something like a zero
    power RGP and let it just reshape the eye rather than correcting it

    Charles, Apr 8, 2006
  11. To answer both of your posts at once, your cost should be between $150
    and $250 for a pair of lenses that can last 2 to 3 years. Disposable
    soft torics can easily cost 80 to 100 dollars every three months, so
    the RGPs are very cost effective.

    As far as fitting philosophy is concerned, I'm trying not to be
    trite when I say "That's why your optometrist went to college for 8
    years." In essence, the fitting of RGPs is both a science and an art,
    and when your doctor selects a back surface curve on the contact that
    beautifully covers the odd front surface of your eye, you just might
    see better than 20/20 with a zero power contact. Once the lens is on
    your eye, the doctor performs an "over refraction" in which he sees if
    any minimal amount of power adds to your quality of vision. As I said
    in an earlier post, soft lenses are "monkey lenses" in any monkey
    can take them out of a foil wrapper and hand them to you. They fit
    like fitting bedroom slippers, when two sizes work for 90% of all who
    try them. Well-fit RGPs are like a custom shoe or a well fit
    suit...nothing works better.
    doctor_my_eye, Apr 8, 2006
  12. Charles

    Charles Guest

    Here's what I'm thinking. Since I have astigmatism, my cornea is not
    shaped the way I'd like it to be shaped. I haven't given up hope that
    my astigmatism could go away some day (it appeared out of the blue 10
    years ago). Reading about RGP and it's effects leads me to think that
    the contacts could subtly "train" my cornea by reshaping it the way I'd
    like it to be shaped. Reading other descriptions, such as the one
    below, makes it sound more like a retainer; I show up with mis-shapen
    corneas, and you make a contact that conforms exactly to that shape.
    Seems like that would tend to make my eye stay the same rather than
    change -which could be good or bad of course.

    I guess the different descriptions seem to be slightly in conflict.
    Does RGP reshape the cornea, or fit it like a glove? I thought that
    hard contacts tended to improve uncorrected vision in the short term,
    but that doesn't fit with the "fit like a glove" description.


    Charles, Apr 9, 2006
  13. Charles

    Charles Guest

    I wasn't really talking about myopia. I only have astigmatism.

    I've heard that pilots used to try to pass their eye tests by wearing
    hard cotacts and then taking them out just prior to the test. The
    examiners had to develop a method to tell whether this was the case.
    Unless this isn't true, it indicates some kind fo retainer effect.

    But maybe you're simply saying that nothing like this can prevent
    eyeball elongation or whatever causes myopia in most people. If I
    understand astigmatism correctly though, it's all in the cornea?

    Charles, Apr 9, 2006
  14. Charles

    Charles Guest

    Here's what got me started:

    "RGP lenses may also be used because their "stiffness" acts to shape
    the cornea to a small degree and may correct mild to moderate cases of
    astigmatism (RGP lenses may help mask up to 3 diopters of astigmatism)."

    Charles, Apr 9, 2006
  15. Charles

    Dr. Leukoma Guest

    Charles, the answer is that RGP lenses, over time, have a
    "sphericalizing" effect on the cornea. The shape of the cornea is
    indeed influenced by the shape of the lens back surface. This is why
    long-time RGP lens wearers make poorer candidates for orthokeratology.
    A patient with large amounts of corneal astigmatism is not going to do
    well in a spherical back surface lens, no more than a square peg would
    fit in a round hole. However, those with small to moderate amounts of
    corneal astigmatism will see it diminish with RGP use in most cases.
    Ortho-k can get rid of astigmatism within the treatment area, but not

    I take advantage of the corneal shape changing effects of RGP contacts
    all the time when working with failed LASIK cases. Patients invariably
    see better once the lenses are removed. You can go to my website and
    look at the Powerpoint presentation to see how and why.

    Dr. Leukoma, Apr 9, 2006
  16. Charles

    Charles Guest

    Sorry to ask the same thing over and over, but how is it that the RGP
    could sphericalize the cornea if the back of the RGP lens itself is not
    speherical? Or is it? My understanding was that the back of the RGP
    is a custom fit, so if I have astigmatism, the back of the RGP would
    reflect that. Or is it that you sort of split the difference and err
    on the side of slightly spherical to the extent that you think the
    cornea can mold? So for mild astigmatism you use a mostly spherical
    RGP, but for more you start to deviate?
    Charles, Apr 11, 2006
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