Problems with "poly" variants - can someone please explain?

Discussion in 'Optometry Archives' started by Steve Y, Nov 28, 2006.

  1. Steve Y

    Steve Y Guest

    I tried "poly" lenses 5 years ago and found them uncomfortable, so my
    lenses were switched to "plain plastic" and I've had no issues. I opted
    for new frames after a recent exam (same Rx) and went for Silhouettes.
    I was told that only poly lenses can be used in them. I reminded the
    optician about my previous encounter with poly, so he suggested Trivex.
    Well, they gave me problems. It fealt like what I remembered dirty
    contacts to feel like (20 yrs. ago). So, they ordered "hi-index 1.60"
    lenses. They are better, but I still have some minor discomfort after
    4-5 days. I called my opthomologist and he said some people get used to
    "poly" and some never do. Ironically, my old lenses are sooooo
    scratched, yet that doesn't bother me except when it creates a large

    My prescription is -250 -250. These lenses have polished edges.

    I have read a number of posts here, but lack the training to fully
    understand the issue and lens options.

    Can someone explain the difference between poly, Trivex, and high
    index? Also, are there are other lense options for these frames (I
    think they said 1.80)? And if I'm out of options, should I try to get
    used to them for a while or can this cause harm in any way?

    Thank you very much.
    Steve Y, Nov 28, 2006
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  2. Steve Y

    Steve Y Guest

    BTW - I have also been wearing Oakley prescription sunglasses for about
    4 years and they are the most comfortable glasses I've ever had and no
    issues at all. I believe they're "poly" so ???????????
    Steve Y, Nov 28, 2006
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  3. Steve Y

    Steve Y Guest

    Thanks Robert. The store went from my measurements on file from my
    plastic lenses and didn't check me for this purchase. Who should "Check
    the vertex distance, vertical and horizontal OCs, panto, and look for
    warpage, waves and surface imperfections."? Is that something the store
    should do or at this point does that require an opthomologist?
    Steve Y, Nov 28, 2006
  4. Steve Y

    Mark A Guest

    Poly is OK when there is now lens power.
    Mark A, Nov 29, 2006
  5. Steve Y

    Mark A Guest

    There are two kinds of lens that have high impact resistance and high
    tensile strength. One is polycarbonate, which has an index of about 1.59.
    Polycarb has the lowest (worst) "abbe value" of any generally prescribed
    lens (abbe value is 30). Abbe value is a measure of chromatic aberration,
    the higher the better.

    The other lens with high impact resistance and high tensile strength is
    Trivex (sold mainly by Hoya and Younger in the US), which has index of about
    1.53. Therefore your lens will be thicker and heavier than a higher index
    like polycarb, but Trivex has an excellent abbe value of about 43. Some
    people say that Trivex has a slight tint to it, but if you put on a high end
    AR coating, then you may not notice it. I don't understand from your post
    above exactly what your problem with Trivex was, so it might help if you are
    more specific.

    Both polycarb and Trivex are very good for lenses that are drill mounted
    because of their very high tensile strength and resistance to cracking.

    Other "plastic" lens materials are available from 1.50 index (called CR-39,
    hard resin, or regular plastic) all the way up to about 1.74. usually the
    higher the index, the lower the abbe value (worst the optics), but the
    higher the index lenses will be thinner and lighter (because less material
    is needed for a given lens power).

    For a -2.50 (it is not 250) Rx, which is low to moderate in strength,
    getting a lens with an index higher than about 1.55 is not necessary to keep
    the lens thin and light. For the best optics, you should get the lowest
    index lenses you are comfortable with. 1.80 is not widely available in the
    US, and is completely ridiculous for someone with a -2.50 Rx (it might be
    needed if your Rx is -12.50) and is one of the few lenses that would be
    optically worse than polycarb.

    Trivex (1.53) should be thin and light enough for your Rx, and is very good
    for drill mounts, and has excellent optics. I would try to find out exactly
    what lens you have and exactly what was wrong with the Trivex lenses you
    tried. Most people who have tried Trivex are very satisfied with the optical
    Mark A, Nov 29, 2006
  6. Steve Y

    Steve Y Guest

    Mark, thank you for the detailed explanation. The moment I put on the
    Trivex in the store I felt discomfort, particularly in my left eye.
    Within 2-3 minutes of wearing it in the store for the first time, my
    wife and the optician noticed my left eye becoming bloodshot. Most of
    the time wearing it I would feel discomfort on my eyeball, as I said,
    like an irritation the way I remember dirty contacts to feel. Possibly,
    there was a little more tearing too.

    Today, I wore the 1.60 lenses for about 11 hours and they were
    bothering me to a lesser degree. Within 15 minutes of switching back to
    my old (same Rx) scratched plastic lenses the discomfort was subsiding.
    I can only imagine it has something to do with how light or the
    magnification is being presented to my eye (????) but that still leaves
    no path to a solution. Currently I'm trying to train my eye to these
    lenses, but today's "training" doesn't look promising.

    Still looking for solutions...
    Steve Y, Nov 29, 2006
  7. Steve Y

    Mark A Guest

    I very much doubt your problem has anything to do with the Trivex lens
    material, if that truly is what you received.

    The number of errors in grinding lenses to the correct power and fitting
    lenses (for proper placement in the frame so it is optically centered) is
    much higher than you would suspect. And there are sometimes errors made
    during an eye exam by an OD.

    Any time you have a problem like you had with the Trivex lens, you need to
    take the lenses to another optical shop and have them measure the Rx of your
    new and old lenses. You also may need to move the frame around on your face
    to see if the lenses are the proper distance from your eyes, are at the
    correct angle, and are optically centered.

    Anytime you are dissatisfied, ask for a second opinion from a different
    optician or OD. Do not even talk to young sales people in a Optical shop,
    always talk to the most experienced person you can find.

    I would really like to know what kind of optical shop you have used (large
    chain, local independent, optical shop in OD office, etc.).
    Mark A, Nov 29, 2006
  8. Steve Y

    Steve Y Guest

    Mark, thank you again. I originally was examined by an Ophthalmologist
    who confirmed that my existing Rx (-2.50) was still correct for me. I
    then went to the optician I have used for the past 6 years to get the
    glasses. They are located in a large mall, but I'm not sure that they
    are anything but an independent operator. They have been very
    cooperative, but again, used my on-file specs. for this order, without
    re-measuring. I've never had an Ophthalmologist provide anything but
    the basic lens power on the Rx, leaving the rest to the optician.

    The message I'm getting from you is that Trivex was a better product
    that may have been produced wrong for me. I basically asked about that
    and when I first went back, they measured them and said that they met
    the proper specs. (???)

    I called the opthamologist's office and they said a small # of people
    don't adjust to poly (I specifically said Trivex).

    I don't know where the Trivex lenses are now, but my understanding from
    you is that I'm on the wrong path with high index. The optician has a
    store credit only policy, so I'm bound to them. I would like to make
    these frames work for me but don't know who can determine the real
    issue or where to turn to resolve it? Are there people who don't adjust
    to properly made Trivex?
    Steve Y, Nov 29, 2006
  9. Steve Y

    Mark A Guest

    Given that Trivex has an abbe value of 43 and is considered to be one of the
    best materials in terms of optical quality, I don't think the Trivex
    material is related to your problem. It could be the lens design (lens make
    and model), the grinding of the lens, or the fitting of the lens in the
    frame so that it is optically centered. Trivex is not the same as polycarb,
    so I don't understand the comment from your Ophthalmologist about not
    adjusting (but Trivex is relatively new and not everyone is familiar with

    I would suggest that find out the exact make and model of the Trivex lens.
    There are only 2-3 lens suppliers in the US (Hoya and Younger are the main
    ones) that are licensed to use Trivex material.

    Personally, I would not recommend an ophthalmologist for an eye exam. They
    are medical doctors who spend most of their time with eye diseases and other
    serious eye problems, while Optometrists (OD) spend all their time doing eye
    exams. However, if you do have an eye disease, then stay with your

    I notice that you did not specify a correction for astigmatism in your Rx.
    Is that correct or did you just leave that part out of your post. It is
    somewhat unusual to need any correction for astigmatism, but not totally
    unheard of. Also, I am assuming that you have single vision lenses and not
    progressives, since you did not state an "add" power for the reading area.

    For a simple single vision -2.50 Rx, you should be able to easily find a
    pair of glasses that give you good vision without any problems. As I
    suggested earlier, if you have any doubts about a lens, then you should take
    them to another optician to have them measured. Or your could take the lens
    made by the optical shop to your ophthalmologist. Have them compare the old
    (good) and new lenses.

    When purchasing a lens, always make sure you know the lens manufacturer
    (Hoya, Younger, Sola, etc), the lens model, and the lens material. Otherwise
    you may be purchasing substandard products. If they don't know, or will not
    tell you, go somewhere else.

    You would not believe the number of mistakes that are commonly made in the
    process of making glasses, and the optician may not be able to recognize
    their own mistake. About 15 years ago, I purchased a pair of single vision
    lenses from EyeMasters (at that time owned by Sears). When I got the
    glasses, I immediately told them I could not see anything out the lenses.
    Several employees re-measured the lens power and they said it was correct.
    Finally, after much complaining, I found another employee who realized that
    the astigmatism correction (cylinder and axis) was ground backwards. This
    kind of gross incompetence is not rare.
    Mark A, Nov 29, 2006
  10. Steve Y

    Steve Y Guest

    Thanks again. No disease/issues. Single vision. No astigmatism. Same Rx
    for at least 10 years. Oakley's "proprietary" poly Rx sunglasses no
    problem for me. So is there this issue that some people don't adjust to
    Poly? And if so, that doesn't apply to Trivex? Am I correct that the
    Trivex lenses have to be checked installed in the frames?
    Steve Y, Nov 29, 2006
  11. Steve Y

    Mark A Guest

    Some people are more sensitive to polycarb distortions than others, and it
    is more noticeable when the lens power increases. Moderate to high power
    plus lenses (+) have more of a problem with polycarb than minus (-) lens
    powers. If you have Rx sunglasses in polycarb, some of the problems (such as
    chromatic aberration) may be less noticeable because of the tinting.

    Trivex does not have the same problems as polycarb in terms of "adjusting"
    to the poor optics, because Trivex does not have poor optics. The only
    downside to Trivex is that it is lower index (1.53) than polycarb (1.59),
    which means that it is thicker and heaver for a given Rx, but that should
    not be much of an issue for a -2.50 Rx. Trivex also has a slight tint to the
    lens, but may not be noticeable if you have AR coating.

    Trivex is usually more expensive than polycarb, and only available from a
    few lens manufacturers, notably Hoya and Younger, (but maybe 1 or 2 others
    have recently starting licensing it). Do not be surprised if an optician
    claims they ordered Trivex, but actually ordered something else. Find out
    the lens manufacturer name and model number of all lenses your purchase,
    especially Trivex.
    Mark A, Nov 29, 2006
  12. Steve Y

    Steve Y Guest

    Mark, you are a wealth of information! Do you work in the industry?

    I went to both the Hoya and Younger web sites to look up their info on
    Trivex and I don't see any listing for it. I see that PPG makes the
    material - do they use PPG material and then brand it? If so, do you
    know which is which? Also, I ordered both lense types with the Cryzal
    coating - any thoughts on that?
    Steve Y, Nov 29, 2006
  13. Steve Y

    Liz Day Guest

    Given that Trivex has an abbe value of 43 and is considered to be one of the
    An Abbe value of 43 does not sound terribly good, as I find (using
    Google) that CR39 plastic has an Abbe value of 57.8, almost as good as
    glass. 43 is less than halfway between this and 35, the Abbe value of

    Is there some other aspect of Trivex that makes it have good optical

    Liz D.
    Liz Day, Nov 29, 2006
  14. Steve Y

    Mark A Guest

    Hoya sells it as "Phoenix" and Younger sells it as "Image".

    If I had a choice, I would use Hoya Phoenix.

    Crizal, and the easy to clean Crizal Alize. are both excellent (durable) AR
    coatings. Crizal is made by Essilor, but is available on some other
    manufacturer's lenses also. But I would be a little suspicious of Crizal on
    Trivex, since Essilor does not offer Trivex. As I said, some labs will put
    Crizal on other lenses beside Essilor, but I would double check that.

    You should be able to get a finished -2.50 lens from Hoya that comes with a
    Hoya AR coating applied by the factory. A finished lens does not have be
    custom ground at a local lab, which eliminates one more variable in the
    Mark A, Nov 29, 2006
  15. Steve Y

    Mark A Guest

    Every polycarb that I have seen has an abbe value of 30. Where did you see

    Actually, polycarb has some additional distortions (besides chromatic
    aberration) over and above most other lenses that are not measured by the
    abbe value.

    Yes, CR-39 (1.50 index) has a very high abbe value, but it is thick and
    heavy for someone who has more than a mild Rx, and most people wear high
    index lenses these days (usually 1.60, 1.67) which have an abbe rating of
    about 34-38. And of course polycarb (1.59) is often used and has an abbe
    value of 30. So an abbe value of 43 is quite good for a lens with very high
    impact resistance and very high tensile strength. This is an issue for the
    OP who wants drill mounts for his frame.

    Aside from being good for drill mount frames, polycarb and Trivex are the
    only lenses that are approved for those who need "safety" lenses, such as
    children, those who play sports with glasses on, or for someone who works in
    a lab or factory. In the US, all opticians have a "duty to warn" customers
    that they recommend polycarb lenses for children or for other people who
    have need for safety lenses. Often times polycarb is sold to minimize legal
    liability, rather than to provide good vision.
    Mark A, Nov 29, 2006
  16. Steve Y

    Steve Y Guest

    Mike, thank you for the added input and test idea.

    In my house now I can only test myself to about 40 feet of distance and
    for comparison I tested with both my old glasses and the new
    (currently) high index lenses. It's hard to say for sure what the exact
    results are but here goes:

    I thought sometimes w/the old lenses one eye saw the object a little
    larger than the other (??) but not much in the way of movement vert. or

    Most of the time with the high index it seemed like there was a little
    change diag. affecting the object height a little. (??) Sometimes I
    wasn't sure.

    My eyes are tired now...

    Should this be done outside with real distance? I'm guessing this is
    only a preliminary means to make a judgement and that true lense
    measurements are needed. (??)

    As far as I can tell both the Trivex and high index lenses have been
    crystal clear to me. No blurring, no waves, and causing no headaches.
    The discomfort with the Trivex started (as I described) like the way I
    remember dirty contacts to feel (from 20 yrs. ago) - kind of
    itchy/irritating. Both lense types cause an ache in my eyeballs (feels
    like the schlera area) - particularly on the inner sides adjacent to my
    nose and sometimes towards the bottoms. As the hours pass while wearing
    the glasses the ache increases from a very mild discomfort to enough of
    an annoyance to put my old scratched up glasses back on. 15 minutes in
    those and the aching is disappearing. I believe the high index cause it
    less than the Trivex did, but I don't have the Trivex to compare
    side-by-side. I can't see wearing them day after day and having this
    discomfort, let alone wondering if there's a physical effect taking
    place on my eyes.

    I was a mechanical engineer w/NO optical training. So my layman's guess
    (emphasize guess) based on the way my eyes feel, is that they have to
    focus towards the outside (left and right) and strain the inner side.
    But of course I don't know.

    Thank you.
    Steve Y, Nov 30, 2006
  17. Steve Y

    Mark A Guest


    I did not respond to your original post, because I have you in my killfile
    for the absolutely ridiculous arguments you get into with the quacks on this
    forum. Or maybe you are one of the quacks, I don't even remember. But I did
    see that your post above is included on the response of the OP, so I will

    Since I don't work in the optical industry, it is not even remotely possible
    that I have any marketing agenda. Polycarb, with an abbe value of 30, has
    the worst optics as any other lens that is generally dispensed in the US.
    That is a fact. Indexes beyond 1.74 is not widely available and not
    generally dispensed in the US.

    I never suggested that the problems of the OP had anything to do with
    polycarb, since (as you pointed out) he did not complain about "rainbows",
    swimming (which can occur with SV polycarb), or even peripheral distortions.
    Likewise, I suggested that the problems with his Trivex lens had nothing to
    do with the Trivex material. I did point out that Trivex is substantially
    better in terms of optical quality than polycarb (which is absolutely
    indisputable), even though they both share high tensile strength and high
    impact resistance.

    What I did suggest (in multiple posts) is that his either Rx is bad, or the
    lenses were not made correctly, or the lenses were not fitted correctly. I
    asked him to get the lenses check at a different optician, and to also try
    an OD for his eye exams.

    It is no wonder that you are in my killfile, and you should be in everyone's
    Mark A, Nov 30, 2006
  18. Steve Y

    Steve Y Guest

    I don't get an itchy feeling like an allergy. It's more of a
    strain/annoyance in the areas I indicated. There is no redness. That
    happened the 1st time I wore the trivex, more in the left eye. No
    visible reactions like puffy lids.
    Steve Y, Nov 30, 2006
  19. Steve Y

    Neil Brooks Guest

    Wow. You KILLFILED Mike Tyner??

    Does ANYBODY get through your killfile??
    Neil Brooks, Nov 30, 2006
  20. Steve Y

    Steve Y Guest

    It was hard to get a useful definition of Asthenopia until I found the
    one at:

    Yes! Yes! That's a broad definition of what I'm experiencing -
    particularly to what I believe is the ciliary muscle.

    I'm headed off to the opthomologist's optician later to see what she
    can determine from the glasses. I'll update here later...

    Thank you all again!
    Steve Y, Nov 30, 2006
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