Toric Silicon Hydrogels?

Discussion in 'Optometry Archives' started by MS, Nov 1, 2007.

  1. MS

    MS Guest

    Which brands of silicon hydrogels are available as toric lenses? If more
    than one, what are the differences between them?
     
    MS, Nov 1, 2007
    #1
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  2. MS

    Colin B. Guest

    The two that I know of are:

    Purevision Toric and Acuvue Advance For Astigmatism.

    I have used both. I recently switched from Acuvue Advance For
    Astigmatism to Purevision Toric. I found the Acuvue Advance
    seemed to retain deposits and were much less comfortable after
    about ten days. While the Purevision are thicker and take a bit
    of getting used to, I find them extremely comfortable and easy to
    handle. For me, they last a full 30 days while maintaining
    comfort. At least, that has been my experience.
     
    Colin B., Nov 1, 2007
    #2
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  3. MS

    p.clarkii Guest

    I think Colin summed it up pretty well. Both lenses are pretty good
    and are an excellent addition to my toric fitting sets. I trial most
    of my toric patients in one of these lenses. In contrast:

    1. Av Adv Astig-- hard to handle due to soft "low modulus" nature of
    the plastic; tend to get deposits quickly in many people; considered
    to be quite comfortable by most all wearers; very little rotation and
    easy to fit on patients; would be the obvious winner except for the
    first two points.

    2. PV Toric-- smaller diameter plus tougher "high modulus" plastic
    that folds less and is easier to handle; gets deposits much less than
    Av Adv does; not considered as comfortable due to the high modulus
    nature of the lens; this lens is preferable for 1st time wearers
    since it's easy to insert and remove them but their comfort usually
    isn't as good as AV Adv is probably due to the high modulus plastic.

    If a patient habitually takes out their lenses at night, and doesn't
    has significant problems with contact lens comfort, then there are
    many other HEMA-based torics that work quite well also.
     
    p.clarkii, Nov 1, 2007
    #3
  4. MS

    MS Guest

    Thanks for all the info.

    I have been wearing N&D on both eyes, monovision. At my eye checkup this
    week, the eye doc suggested trying a toric lens on the right eye, to help
    with the astigmatism on that eye. He gave me the Acuvue Advance one.

    I was surprised at how much better my distance vision is with the toric
    lens. (I didn't know I was so astigmatic.) I also find the lens comfortable,
    no different from the N&D in my left eye.

    However, I notice the right eye is red, after wearing the Advance in it for
    just a couple days (including sleeping in it). (I am used to sleeping in the
    N&Ds.) Also, the lens fell out this morning, while rubbing the eye. Anyone
    know why the eye might turn red with the Advance (with no discomfort), and
    why it would fall out?

    My eye doc didn't mention the Purevision toric as an alternative, but
    perhaps I should ask him if I can try that too.

    Which of the two has the higher dK?

    Thanks again.
     
    MS, Nov 1, 2007
    #4
  5. MS

    Mike Ruskai Guest

    Acuvue Advance are not designed for extended wear. It's dK/t is 85.7,
    higher than any other non-extended wear lens I know of, so it's
    probably OK for a few days, but they don't recommend it. PureVision's
    dK/t is 110.

    If you find the N&D lenses comfortable, you will likely have no
    problem with PureVision. They felt identical to me (horrible - it's
    not the modulus, but the sharp edges, versus the very smooth edges of
    Acuvue lenses) when I tried them. And unlike N&D, which has a very
    small optical zone, PV lenses provide excellent night vision.
     
    Mike Ruskai, Nov 1, 2007
    #5
  6. MS

    Colin B. Guest

    With the Acuvue, if I closed my eyes for even a few minutes, they
    felt quite sticky afterwards.
    I find the PureVision Toric extremely comfortable even with the
    sharp edges, more so than the Acuvue, but I find on occasion with
    the Purevision regular contact in my other eye, I do notice the
    sharpness.

    Night vision is a big plus for the Purevision. I am using
    monovision, so might be different, but couldn't stand the Acuvue
    at night when under street lights, as I had serious halo effect.
    This is not a problem with Purevision. In fact, I get better
    vision with Purevision with monovision than I do with either
    regular contacts or glasses. However, I have had cornea problems
    in the past, so the Purevision has a bit of a bandage effect for
    me, more so than with the Acuvue. However, other's mileage may vary.


    Colin
     
    Colin B., Nov 1, 2007
    #6
  7. MS

    MS Guest

    I wonder why my optometrist, knowing that I wear N&D as EW, gave me the
    Advance rather than Purevision? (He may not have had the Purevision toric in
    stock, but he could certainly have ordered one.) He told me the Advance was
    EW, and didn't even mention Purevision.

    I'll have to ask him to try the Purevision.

    Thanks for the info.
     
    MS, Nov 2, 2007
    #7
  8. MS

    MS Guest

    Strange. I just called the optometrist office, and spoke directly with him,
    and asked about the Purevision. He said that the Advance is also for
    extended wear, and also said that it has a much higher dK than the
    Purevision lens.

    I couldn't argue with him about it, but told him I would like to try the
    Purevision anyhow. He said OK, he would order me one to try.

    Perhaps next year though, I should go to a different eye doc. It doesn't
    seem like he is very knowledgeable.
     
    MS, Nov 2, 2007
    #8
  9. MS

    MS Guest

    Is there a chart somewhere on the net that shows the dK of all the silicone
    hydrogel materials?

    Thanks for the info.
     
    MS, Nov 3, 2007
    #9
  10. MS

    p.clarkii Guest

    i believe that the expense of FDA approval is one factor for why some
    companies don't seek out extended wear certification for products that
    could almost certainly attain it, but more likely its good ol' product
    positioning. CIBA, for example, could almost certainly get EW
    certification for 02 Optix but why undercut their existing customer
    base who already pays 3 times more for Focus N&D? Similarly Vistakon
    probably tries to position Oasys as their "EW-preferred" lens so as to
    justify why someone should pay so much extra for it. I think
    marketing has a lot to do with EW certification in recent years.

    my Vistakon rep has "hinted" that the entire AV Adv toric line will
    likely be "updated" within the next year or so with a more Oasys-like
    material. I think Vistakon is sensitive to the problems that Advance
    has with increased deposits in many patients.

    I am one of the guilty eye docs who, under certain circumstances, will
    put people into Av Advance for EW. I do that for patients who are
    obvious CL abusers who will sleep in whatever lens they buy and will
    only buy inexpensive ones. I guess I figure I'd rather have them
    sleeping in Advance (or preferably 02 Optix) than in polymacon or some
    other old plastic like they currently use. it's picking the lesser of
    two evils I guess.
     
    p.clarkii, Nov 3, 2007
    #10
  11. MS

    MS Guest

    But why choose between those two choices? Why not recommend that they get
    N&D, Purevision, etc., if they want EW?
     
    MS, Nov 3, 2007
    #11
  12. MS

    Mike Ruskai Guest

    There used to be a free search function at www.eyedock.com, but it's
    now subscription-only.

    But if you search for the lens name and "dk" on Google, you'll usually
    find a figure. Just check a few different results to reduce the odds
    of you seeing a typo or just plain incorrect figure.
     
    Mike Ruskai, Nov 3, 2007
    #12
  13. MS

    Mike Ruskai Guest

    Perhaps his patients, like me, find those lenses incredibly
    uncomfortable. My Oasys disappear in my eyes after a few seconds when
    I put them in. N&D and PureVision were still horrible after more than
    an hour, so I gave up trying the latter (the former I gave up as soon
    as I saw they were incapable of focusing a star image at night, due to
    the small optical zone).

    I expect there are people for any given lens who can't stand the feel
    of it.
     
    Mike Ruskai, Nov 3, 2007
    #13
  14. MS

    MS Guest

    I guess, that since before I wore the N&Ds I was wearing RGPs for thirty
    years, the N&Ds felt very comfortable to me.

    I would like to try the new Biofinity lenses, however, as they are supposed
    to be so comfortable. (In my left eye, which doesn't need toric.) (They are
    approved for thirty days wear in other countries, but have not yet gone
    through that process here in the USA, (Why does our FDA always take longer
    to test these things?) so they are listed in the USA for now as being for
    daily wear.) Have you considered Biofinity?

    Oasys is approved for EW, correct?
     
    MS, Nov 3, 2007
    #14
  15. MS

    p.clarkii Guest

    Price. Focus N&D pricing is exorbitant. Purevision is better but
    still much higher than lenses with similar Dks.
     
    p.clarkii, Nov 3, 2007
    #15
  16. MS

    MS Guest

    When you discuss price, do you mean price per lens, or price per month?

    With N&D you change lenses every month, according to the recommended
    schedule. Are Oasys lenses also changed monthly? If they are changed every
    two weeks, and the lenses cost twice as much, the monthly cost is the same.

    I'm sure the manufacturers set the price per lens, according to the
    replacement schedule. Is there really such a difference in the overall cost,
    of the different SH brands?

    I usually buy N&Ds online, and the price is usually about $50 per box of 6.
    That is a 6 month supply, for one eye. So, a yearly supply, for both eyes,
    costs around $200. Is the yearly cost of Advance or Oasys a lot less?
     
    MS, Nov 3, 2007
    #16
  17. MS

    MS Guest

    How often is it recommended that Oasys be changed? Two weeks?

    Are you suggesting that many users do not replace lenses as the manufacturer
    recommends, but keep the lenses longer?

    Is there really a difference between lenses that indicate that some can be
    kept longer than others (some for only one day, others for a month, others
    in between), or is the designation of the wear length of lenses made
    entirely for economic reasons? (It's clear though, that they are going to
    charge considerably more for a lens changed once per month, than for one
    changed every day.If not, they would lose a lot of money on the monthly
    lenses.)
     
    MS, Nov 4, 2007
    #17
  18. MS

    MS Guest

    What is the pricing like on Biofinity, the new monthly lens by Coopervision?
    They are not even available online, so I assume one can only get them (in
    the U.S., at least) through eye docs. I would guess more expensive than N&D
    and Purevision. How much for a six lens box?

    Also, those are currently only rated for daily wear in the US, although they
    have been approved for 30 day continuous wear in other countries. Are docs
    recommending their use for EW here anyhow, since they have been approved for
    it in other countries?
     
    MS, Nov 4, 2007
    #18
  19. MS

    Mike Ruskai Guest

    Where I get my lenses (lens.com), Oasys are currently $18.24 per box
    of six lenses when you buy eight boxes (i.e. 48 weeks worth if you
    replace them every two weeks). N&D are $42.99 per box if you buy at
    least four boxes.

    If you do the math, and use the "official" lifetime of the lens,
    that's about $0.43/day for Oasys, and $0.48/day for N&D.

    That's not that big a difference, so you might call Oasys a premium
    lens as well, but worth it in my opinion.

    PureVision comes out to $0.34/day, feels the same as N&D, and has good
    night vision.
     
    Mike Ruskai, Nov 4, 2007
    #19
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