material and other questions

Discussion in 'Optometry Archives' started by Bob S, Apr 13, 2005.

  1. Bob S

    Bob S Guest

    Prescription

    +2.00 -.50 60
    +2.75 -.50 135
    Add +1.75

    I was offered lenses of "mid-index" material. They seemed not to know
    the actual name of the material. They said that it was a cast plastic,
    not ground, and that the index was 1.5370. They did not have the Abbe
    number; he said it was "as good as regular plastic". I got the
    impression that nobody had ever asked these questions before.

    The price was $75 per lens with "Platinum" finish; apparently an
    anti-reflection coating. The price was the same without that finish.
    Does anyone have experience with the finish?

    Any speculations as to what the material might be, whether it might
    offer any advantage over regular plastic, and whether the price is
    reasonable (it seems a little more than regular plastic)?

    The frames were about $90; Stetson 171 56-16+50. They have a new-to-me
    nose piece; it is a single piece of bent metal (inverted U shape)
    riveted to the frame in the center and covered with soft plastic. You
    adjust it by bending the metal. It seemed like it might offer the
    adjustability of the pad-on-wire things while giving a broader contact
    area so less pressure. Does anyone have experience with this?

    Bob S
     
    Bob S, Apr 13, 2005
    #1
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  2. Bob S

    Mark A Guest

    You have discovered that large numbers of people selling glasses these days
    are not very well qualified.

    However, what you were probably offered was Sola Spectralite, which is
    available on Sola PAL lenses like the Solamax, Percepta, VIP Gold, etc. The
    reason I say that is that Spectralite has the identical 1.5370 index.
    Although other companies make mid-index lenses, it is unlikely they have the
    identical index since Spectralite is proprietary (unlike polycarb or regular
    plastic). You could confirm this by inquiring about the lens manufacturer
    and PAL design.

    Spectralite is a very good material with an abbe value of 47 (regular
    plastic is 58, but much heavier and thicker with an index of 1.5). It would
    be very appropriate for someone with an Rx like yours.

    I don't know about the platinum finish, but I would be wary of any cheap AR
    applied because it could easily be damaged, which would ruin your lenses.
    The better AR coatings from the manufacturers are more durable. Crizal/Alize
    is one of the most durable. Sola has a AR coating called UTMC. If the
    coating is applied at an in-store lab, don't get it. However, not too many
    AR coatings are free, so it may be an anti-scratch coat which comes with
    most lenses, or it may be an edge finish. But it is possible that Platinum
    is the name they use for UTMC to make it more difficult to compare prices.

    Usually there is at least someone in an optical store that knows what is
    going on, so ask another person, or ask when the manager will be available
    if a salesperson cannot answer your questions.

    I don't know about the price, but Wal-Mart has offered Sola products in the
    past, so you could compare prices there. But they don't always offer all
    materials in all lenses, even if they still offer Sola.

    Is there some reason why you didn't disclose the name of the optical? Unless
    it is an OD office or a local optical with only 1 store, then it helps us to
    know who you are dealing with.

    I can't help you with the frame, but make sure it is fitted to your face
    comfortably before you buy the lenses (and before they measure the fitting
    height, etc).
     
    Mark A, Apr 13, 2005
    #2
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  3. Bob S

    Bob S Guest

    Sorry, I wasn't being mysterious, just incomplete.

    The place is a Wal-Mart, so I wasn't expecting terrific expertise.

    It is not PAL glasses that I was offered, just ordinary bifocal
    lenses. Does Sola do them in SpectraLite also?

    Bob S
     
    Bob S, Apr 15, 2005
    #3
  4. Bob S

    Bob S Guest

    Sorry for the omission; it was entirely due to not paying attention;
    after all, I knew what I was talking about, doesn't everyone :)

    Anyway, they are not PAL lenses, just simple bifocals. Does Sola do
    ordinary bifocals in Sprectralite?

    Thank you for the caution regarding the frames; I will look for
    something else.

    Bob S
     
    Bob S, Apr 15, 2005
    #4
  5. Bob S

    Mark A Guest

    Sola makes the ASL ASPHERIC FLAT-TOP 28 bi-focal in Spectralite which comes
    with Perma-Gard Plus coating. I don't believe that this is an AR coating,
    but not absolutely sure.

    The head optician at Wal-Marts are usually pretty knowledgeable, so ask to
    speak to them if the person you are talking to does not know the answer
    (coatings, etc). If the head optician is not there, ask when they will be
    there.

    Wal-Mart usually caries name brand products, but their selection is somewhat
    limited. So you should be able to find out exactly what the coating is.
     
    Mark A, Apr 15, 2005
    #5
  6. Bob S

    Bob S Guest

    Today I tried a local optical shop. They will also do Spectralite
    bifocals, at almost exactly the same price per lens as Wal-Mart. They
    even know what the material is ;-)

    The frames are slightly more expensive, but they are better frames, so
    that is OK. They are offering the same frame I now use. It says
    "Cottet" and Tech 21 50 19 140, whatever all that means.

    The big difference is what they offer for AR coating. They say they
    use "Crizal Alize", which I guess is good stuff, but is $95! This is
    compared to Wal-Mart's "Platinum", whatever that is, for free.

    I asked about durability of the coatings and he said that it was
    "better than they used to be", and that they very rarely have
    problems. He also said that you cannot just "clean them on your shirt
    tail" (why not, its just cotton?).

    What are the experiences with this AR coating? Is it worth all that
    money? Will it stand up to reasonable use? Will it tolerate hot water
    rinses for grease removal?

    Bob S
     
    Bob S, Apr 21, 2005
    #6
  7. Bob S

    Mark A Guest

    Crizal Alize is probably the best AR coating available for two reasons. It
    is fairly durable (for an AR coating) and it is easier to clean than other
    AR coatings. You can use a mild detergent and not/warm water to clean a AR
    coated lens, but not scalding hot.

    You should not use dry cotton to clean any lens because you are just
    grinding the dirt against the lens while you attempt to remove the dirt. You
    can gently use cotton to remove the excess water after you have properly
    cleaned a lens with a mild detergent and warm water, but it should be
    absolutely clean and free of dust or dirt (which cannot be guaranteed with a
    shirt you are wearing).

    Have you ever tried to clean a camera lens. Most good cameras have an AR
    coating on them.

    The expected life an AR coated lens is about 2 years, maybe a bit more with
    Crizal if you are very careful. So if that is OK, then it is a good idea,
    but it certainly is not mandatory that you have AR coating.

    On your frame, I assume Tech 21 is the model number. 50 is the lens size, 19
    the bridge width, and 140 the temple length. These are in millimeters.

    I would call Wal-Mart and ask them for availability and price on Crizal
    Alize. Plain Crizal is also durable, but not as easy to clean.
     
    Mark A, Apr 21, 2005
    #7
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