High index lenses for low/moderate Rx?

Discussion in 'Optometry Archives' started by Chuck, May 7, 2010.

  1. Chuck

    Chuck Guest

    I'm wonderng if it is at all typical for people to prefer high index
    lenses for vision quality, as opposed to just for cosmetic reasons or
    to keep things lighter. My rx is not high, but I think I'm finding
    that I much prefer the high index. I have two pairs of glasses with
    the same Rx, one in regular plastic and the other in aspheric high
    index (1.67 I think). I feel like I'm in a fish bowl in the regular
    ones, plus stuff turns blurry if I look to far off to the side. The
    high index ones are much better. Does that make sense or could it be
    something else?

    I had some Izon glasses that I liked too, and I was thinking that the
    reason why was not because of the fancy wavefront stuff, but simply
    because all the high index aspheric stuff came on them by default.

    Chuck, May 7, 2010
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  2. Chuck

    Mark A Guest

    Usually it is the opposite. The higher the index, more chromatic aberration
    (specified as abbe value, the higher the better) usually occurs. The
    exception is polycarb which has the lowest abbe value of any commonly
    prescribed material, but is only 1.59 index. Are you sure you have regular
    plastic and not polycarb?

    One explanation may be that if your vision has adapted to your 1.67 lens,
    the regular plastic 1.50 lens may appear distorted because you are used to
    the distortions of the 1.67 lens (especially those caused by an aspheric

    The regular plastic lens may not be the correct Rx any more, especially with
    regard to cylinder/axis correction (for astigmatism). Are you sure the Rx's
    are identical on both lenses? Also, both lenses may have been ordered with
    the same exact Rx, but there may have been an error in the regular plastic
    lens when it was made. It is also possible that the 1.67 lens was fit better
    by the optician (closer to your eyes and properly centered), although most
    regular plastic 1.50 lenses are spherical and not as sensitive to lens
    fitting as aspherical designs.

    Are you lenses single vision or progressive? If they are progressive, the
    high index lens may have a more sophisticated progressive design than the
    regular plastic one.
    Mark A, May 7, 2010
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  3. Chuck

    Chuck Guest

    I have single vision lenses. The ones that are giving me trouble are
    transition lenses and are not poly. The distortion I'm having the most
    trouble with is not like a chromatic abberation, but where the shape of
    things varies significantly depending on angle. For example, if I look
    at an object and move my head up and down while keeping my eyes on it,
    the object appears to get taller and shorter. I don't have this (enough
    to notice) in the high index. As I mentioned in the first post, the
    ones I don't like also "defocus" when I look off center too far.

    The order of events was that I got my new Rx from the doc and order
    some glasses. When I got them I could not stand them due to distorted
    fish bowl sensation. We tried a slightly lower power in one eye
    thinking that it was to do with the fact that the differential power
    between eyes had changed by 0.5D. This did not help. I decided to
    order a trial of cheap glasses on-line with 0.25D less astigmatism
    power in both eyes and also got 1.67 while I was at it. I liked these
    right away, so went back to the eye doc and requested 0.25 less astig
    power. When they came back they still seemed weird and distorting
    (though better). I asked right away for the optician to read the new
    ones and the cheapies from on-line and they were within 0.12 on all

    I'm coming from the Izons which I believe are high index aspheric
    automatically. Thing is, when I got those I liked them right away and
    didn't have to "adapt". I have almost never in my life had any success
    with just "giving it a week to adapt". If I hate them when I put them
    on at the office, it almost never works.

    Chuck, May 9, 2010
  4. Chuck

    Chuck Guest

    Thanks for the input. Sounds like I can attribute the difference to
    the aspheric lenses then.

    I did wear RGP contacts for about about a year and I loved my vision in
    them. The drawbacks were dry eyes, limited wear time, discomfort in
    wind and dust, "too big pupil" effects at night, etc. I may go back
    though because, as you say, all the distortion stuff I hate about
    glasses just disappears.

    Chuck, May 9, 2010
  5. Chuck

    Neil Brooks Guest

    There's a Brave New World in contact lens technologies.

    It may BE worth another try.

    Depending on how bad the dry eye issue is/was ... things like lower
    punctal plugs, flax seed oil, or a decent (and preservative-free)
    lubricating drop may make your experience relatively pain-free.
    Neil Brooks, May 9, 2010
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