Progressive Lens Questions

Discussion in 'Optometry Archives' started by Doug, Dec 31, 2003.

  1. Doug

    Doug Guest

    I am converting to conventional glasses from my Lear Vision aviators
    that I have been wearing for the past 15 years (with worsening
    presciptions) due to inability to replace them with a similar
    suspension system as they and similar ones appear to be unavailable
    (if you know of one, I would love not to have to change). We have
    settled on Silhouette Titanium 7458 50.2Y 12 (????) shape and size as
    they seem the least obtrusive and least uncomfortable of the
    conventional styles and the lens seems large enough to be practical,
    not tiny peepers.

    My new prescription is:

    -125 | -150 | 92
    -100 | -150 | 90
    ADD: +225 P.D. 65 / 62

    I have been wearing progressives, no idea what make lens was used in
    the Lears, for many years and am quite happy with them. Now the lens
    choices are so numerous, and the limited information available to a
    consumer about their features so nebulous and pretty much useless (at
    least to me), that I am totally confused as to what will work best,
    especially with this new prescription (about 1/4 diopter worse
    overall). I spend about 10-14 hours a day in front of the computer
    (21 inch monitor at 1024 x 768) with a distance from my eyes of about
    25 - 37 inches (mostly closer rather than farther). I am also a
    general aviation pilot, so both close and far vision is also critical.
    As I noted, my current glasses have worked great, but...

    The optician we have been working with (Paris Optique in Chandler, AZ)
    has recommended a Varilux Comfort polycarbonate lens with Crizal
    coating. Is this the best choice or are there other alternatives that
    might perform better for me.

    Also, he has recommended clip-on sun lenses. Given the extreme high
    cost of the Silhouette glasses (4 times what I paid for my Lears a few
    years ago!) that sounds like a good idea to at least try. Cannot use
    the Silhouette clip-ons as they are apparently only available in
    polarized, which are unacceptable in the cockpit. They also don't
    seem to be able to be put on without taking off the glasses, whereas
    the others shown to me can be done without removing and messing with
    them. The alternative ones he showed me that would exactly match the
    lenses in the Silhouettes weigh more than the glasses, it seems the
    metal parts are not lightweight material. Does anyone make
    matching/custom clip-ons that are made with lightweight clip and
    bridge (titanium?) materials?


    Doug, Dec 31, 2003
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  2. Doug

    Mark A Guest

    Varilux makes good progressives. The Panamic is top of the line and Comfort
    is just below that. For your moderate Rx, Comfort will probably work fine.
    Crizal is an excellent (fairly durable) AR coating. I say "fairly" because
    all AR coatings are much more fragile than an uncoated lens.

    Polycarbonate (1.59 index) has very high tensile strength and impact
    resistance (required for some safety applications), but relatively poor
    vision (especially in regard to chromatic aberration) compared to other
    lenses. But people with weak or moderate correction "usually" do not have a
    big problem with them. Polycarb is somewhat thin and light, and is easy to
    drill for rimless frames (high tensile strength). The Comforts also come in
    regular plastic (1.50 index), and 1.60 index plastic, both with better
    optics than the polycarb.

    If you have the bucks and need lenses with high tensile strength and impact
    resistance, Trivex lenses (1.54 index) have MUCH better optics than
    polycarb, but have a slightly lower index and therefore are little bit
    heaver than the same polycarb lens. Trivex is sold as Hoya Phoenix or
    Younger Image lens material (currently not available from other
    manufacturers). The Hoya ECP progressives typically get good reviews.

    There are many other lens choices. Many people like progressives from
    Rodenstock and Zeiss, but they may be more expensive and in some cases take
    a few weeks to have made.

    Almost all progressives have markings on them that can identify the lens.
    Your optician should be able to id your current lenses. If not, check with
    another optician. Based on my experience, most Wal-Mart opticians will id
    the lenses, and they may also quote you a price on the Comforts.
    Mark A, Dec 31, 2003
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  3. Doug

    Terry Horton Guest

    As with all technologies I generally look to the latest designs. An
    interesting article on "personal progressives" is at The Rodenstock
    Multigressiv atoric lens is often recommended for astigmatism. The
    J&J Definity is also an atoric design. Among newer but more
    conventional designs the new SolaONE looks interesting with its Teflon
    AR. The Hoya Summit ECP which I wear appears to benefit from similar
    visual simulation technologies as the Sola, and Hoya makes substantial
    durability claims for its new AR. The dimensions of your frame will
    limit to some extent determine your lens choice.

    All the above designs will be more expensive than the older Varilux
    Comfort. All are produced only at the manufacturer's facility, and
    some opticians may be less inclined to recommend a lens that can't be
    ground at a lab they have a relationship with; you may have to ask

    I have no trouble snapping on and off the Silhouette clip-on while I'm
    wearing my glasses (takes a little practice but quickly becomes second
    nature). They're far less likely to scratch the lenses than any
    conventional clip-on. And my glasses even fit into the Silhouette
    case with the clip-ons attached(!). May not work for flying but
    definitely something to consider for everyday use.
    Terry Horton, Jan 2, 2004
  4. Doug

    Mark A Guest

    Varilux lenses are only ground at certain approved labs, although because
    its popularity, there are a lot more labs that finish Varilux lenses than
    Hoya in the USA. The Comfort is not the latest Varilux design, which is the
    Panamic, but works well for mild to moderate correction, and is less

    Comparing progressives is always difficult, but I actually found one
    optician who claimed that the Varilux Panamic (his wife had them) was much
    better than the Hoya ECP. Interestingly, he sold the ECP, but not the
    Mark A, Jan 2, 2004
  5. Mark A wrote:

    Well, here is a real stab in the dark, but I'm hoping some experts
    exist here.
    I went to get new lenses (and frames...) and started to run into some
    terms that just baffled me. Actually it was the ignorance of the people
    at the optics shop that baffled me.
    They used the terms: polycarbonate, "regular plastic" and hi-index.

    I near to barfed when I heard the term regular plastic. That is
    like saying
    a building is made of materials or a food recipe is made of ingredients.
    In about a half-hour I could find on the Internet that this regular
    is probably CR-39, an Allyl Diglycol Carbonate. Now that does mean
    something, even if the 'an' is still not specific. But I'm satisfied
    for now.

    So ... can anyone tell me the more specific name of the polycarbonate
    (1.59 index) as used in the optics field and referenced above?
    (CR-39 seems to fit in the polycarb family as it is a carbonate and is
    polymerized. But being 'special', it became 'regular' - such is the
    way of commerce.)

    All I get on the other names is 'proprietary' - OK - keep it a
    secret, but
    could I at least get the general family for 'hi-index' materials, such as
    mentioned above? That is what I got in my frames as I type, but
    as it took 15 trips to various eye exams and the optics shops, I
    have about had it with asking questions the clerks and Docs do
    not seem to understand. What are these made of????

    And to make a real challenge - can I somehow, someway, possibly
    get a few sample blank disks of some of these various plastics used
    for optics? I've got plenty of PMMA for my experiments and a choice
    of sources in a wide variety of shapes. But I'd like to toss a few of
    these other clear polys into the mix to see what comes out.
    Do I have to join a priesthood to access these esoterica, or should I try
    the Hamfests for surplus materials?

    Wm. Hathaway

    (See for examples of our experiments

    with PMMA.)
    William H. Hathaway, Jan 6, 2004
  6. Doug

    Mark A Guest

    I am not a lens expert, but regular plastic (CR-39) is very different than
    polycarbonate lenses used for glasses. It is different in refraction index
    (1.50 vs. 1.59), optical quality (58 abbe value vs. 30 abbe value), specific
    gravity (1.32 vs. 1.20 g/cm3), tensile strength and impact resistance
    (polycarb is MUCH higher and required/recommended in certain situations). I
    don't think that CR-39 could be considered a polycarbonate as the term is
    used in the optical industry.
    An optical chain normally sells a rebranded lens and does not want to tell
    you what it is (which makes it harder to comparison shop, sort of like
    buying a bed). But a rebranded lens that is purchased from a major lens
    manufacturer is not the same as a proprietary lens.

    Many of the so-called proprietary lenses fall into categories that are
    similar to other lenses on the market, even if they are still under patent.
    There are some exceptions such as Sola Spectralite, Trivex (Hoya Phoenix or
    Younger Trilogy), and others. I assume that polycarbonate was at one time
    proprietary, but probably the patent has expired.
    Mark A, Jan 6, 2004
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