Choosing new Anti-r. coating and "poly carb." vs "high-index"

Discussion in 'Optometry Archives' started by Craig, Jul 29, 2004.

  1. Craig

    Craig Guest

    Dear folks:

    I am a layman who is getting a new prescription filled soon. I am
    seeing an eye specialist next week for an eye exam. I am posting this
    bc I am trying to determine whether the advice I got from an optician
    recently seems valid or not. Any light you might be able to shed on
    this would be highly appreciated!!

    The optician looked at my current glasses to ascertain the current
    prescription. I don't know what this reflects, but he said it the
    power was a "-6". I have progressive lenses with a Zeiss
    anti-reflective coating. After a short time wearing these glasses,
    they developed small scratches and a round smear mark on my left lens
    which he said resulted from a poor chemical bonding process in the
    anti-reflective coating procedure. I've had the glasses for about 5
    years and have noticed a drop off in my vision, so I am going for a
    eye- exam in a few days to get a new prescription.

    His advice which I would like your imput if possible was this: He
    suggested I go with "Crizal" anti-reflective coating for a superior
    chemical bonding process and less chances of more scratches and
    defects. He also suggested I get a "high-index" 167 Verilux
    progressive lens. He said that with my current prescription ("-6) he
    didn't recommend "poly-carbonate" lens (he didn't recommend this lens
    for lens over "450"). Does this seem like sound advice? If my
    prescription changes (ie., is no longer "-6") when I go for my
    upcoming eye exam, could this alter this advice-- in other words,
    might "poly-carbonate" lens actually be better for me than the "high
    index 167" depending on how strong the prescription is?

    I don't really understand most of the sophisticated terminology in
    this field, or what the numbers I shared with you really represent,
    so if you could explain things in as simple terms as possible, this
    would really help!!! I really appreciate any help you can give or any
    places you can recommend I check out on the Web for more info...

    Craig Smith
    Craig, Jul 29, 2004
    1. Advertisements

  2. Craig

    Mark A Guest

    You have received some good advice.

    Crizal is one of the most durable AR coatings on the market, but no AR will
    likely last 5 years unless you are exceptionally careful. There is a new
    version called Crizal Alize, which is supposedly easier to clean than
    regular Crizal, but I don't have any first hand knowledge of that. There has
    been a definite improvement in the durability of AR coatings available from
    some labs, although there are plenty of inferior coatings still around.

    Polycarbonate is very impact resistant and has a high tensile strength. It
    is relatively thin and light (1.59 index). Optically, polycarbonate is crap
    compared to almost all other lens materials, which is more noticeable in the
    higher diopter corrections like yours. The only reason to get polycarbonate
    is if you need safety glasses, although there are some advantages of using
    it for rimless frames which need to be drilled. Trivex (Hoya Phoenix, etc)
    is also a safety lens (with a 1.53 index), but has much better optics than

    1.67 is thinner and lighter than polycarb and usually has better optics
    (even though the optical quality usually goes down when the index goes up).

    There are many high quality progressives on the market. Varilux makes two
    models, the Comfort and the Varilux (the premium model). Other premium
    progressive lenses are available from Rodenstock, Zeiss, Hoya, Seiko, and
    Mark A, Jul 29, 2004
    1. Advertisements

  3. Craig

    Mark A Guest


    Varilux makes two models, the Comfort and the Panamic (the premium model).
    Mark A, Jul 29, 2004
  4. Craig

    Craig Guest

    Dear Mark:

    Thanks very much for your detailed and useful reply! Based on what you
    and the optician I saw have said, I'm now strongly leaning towards
    the Crizal Alize A-R coating with the hi-index Verilux comfort
    progressive lens.

    Could I ask a follow-up question? Should I also get the same hi-index
    1.67 Verilux comfort progressive lens (withouth the A-R coating) with
    my new *polarized sunglasses*? Or does hi-index not apply to

    Thanks again!
    Craig, Jul 31, 2004
  5. Craig

    Mark A Guest

    The index applies to any prescription lens material. Generally the higher
    the index, the thinner the lens (less material is needed to bend the light
    waves) and therefore the lighter the lens (for a given frame/lens size). As
    Robert M suggested, sometimes the difference in thickness and weight is not
    all that noticeable, but it depends somewhat on your frames and Rx (high
    power minus lenses can be thick at the edges).

    In addition to the Varilux Comfort, I would get a price on the Varilux
    Panamic, which is their premium lens and is better for some people. You
    might also want to get a price on the 1.60 index material, that has better
    optics than polycarb and 1.67, but less expensive than 1.67 (1.60 is usually
    about the same price as polycarb).

    The Varilux Comfort polarized grey lenses (Panamic is available in grey or
    brown polarized) probably only comes in one lens material, and according to
    the availability chart I looked at, it is only available in 1.50 index
    standard plastic (also known as CR-39). This is material will be thicker at
    the edges than the other materials mentioned because of its lower index, and
    hence it will be heavier because of the additional thickness. However, 1.50
    plastic has excellent optical qualities compared to the higher index
    materials. If thickness and weight are important, and the polarized lenses
    are only available in 1.50 plastic, you might want to consider just getting
    regular Rx lenses tinted with at least 1.59 index to make a pair of
    sunglasses (albeit without polarization).
    Mark A, Jul 31, 2004
  6. Craig

    Craig Guest

    Dear Mark:

    Thanks once more. It never dawned on me that the sunglasses wouldn't
    have the same range of high-index that reg. glasses do. I hope to have
    my new prescription early next week. May I reply again at that time
    when I know more exactly what the prescription will be?

    thanks again!
    Craig, Aug 1, 2004
  7. Craig

    Craig Guest

    Dear Robert:

    Thanks much for your post! I appreciate the feedback....
    Craig, Aug 1, 2004
  8. Craig

    Mark A Guest

    Prescription sunglasses are just normal lenses that are soaked in a dye to
    the desired amount of tint. You can get any of your existing glasses tinted
    at most chain optical stores (unless they are made of glass). Most in-store
    labs also have automated "dipping" machines that can cause the lenses to be
    tinted more at the top than the bottom (if you like that feature).

    Polarized lenses are a special case. These are made by bonding a polarizing
    film in-between two pieces of plastic to make the lens blank, and then the
    lens is ground to your Rx. In the case of Varilux, they only has polarized
    lenses available in regular 1.50 plastic (according to their availability
    chart I saw on their website). I believe that the Varilux polarized lenses
    are pre-tinted also.

    Varilux uses Nupolar by Younger Optics polarized lens material in 1.50
    plastic for their polarized lenses, but I know that Nupolar is also
    available in polycarb from Younger optics, so maybe the Varilux availability
    chart I looked at was incorrect. In any case, you could get Younger Image
    progressives in polycarb polarized lenses if Varilux does not have them (but
    the Image progressive lens design may not be quite as good as Varilux).

    If you don't absolutely need polarized lenses, just get regular progressives
    lenses of your choice tinted to your specifications.
    Mark A, Aug 1, 2004
  9. Your welcome. Informed optical consumers are a good thing. Keep the
    questions coming.

    Unless thickness is a priority I would not use 1.67 in the sunglasses.
    Instead, use a less expensive material and take the money saved and
    put it into a coated lens. A back surface AR coating will eliminate
    surface reflections reducing interference resulting in increased
    visual comfort. Both surfaces can be coated for improved cosmetics.

    Robert Martellaro, Aug 2, 2004
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.