Help with CR-39 lenses for high myopic Rx

Discussion in 'Glasses' started by kal, Sep 16, 2011.

  1. kal


    Sep 16, 2011
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    I am not an eye care professional, so I apologize if this is silly. :eek:

    I'd like some input from the opticians here regarding different types and/or brands of CR-39 lenses for a moderately high myopic Rx (OD -7.00 -0.50 x 180 / OS -6.25 -0.50).

    My current pair of glasses have 1.67 high index lenses with AR coating; unfortunately I do not know what brand they are, or whether they are aspheric in design. I got the 1.67s for their reduced thickness because they fit better with my 49mm (quite large for me, actually) semi-rimless frames. The AR coating was recommended since high index lenses reflect more light to others and cause more glare for the wearer. Overall, I have been satisfied with them, but I do have three complaints:

    1) I notice a LOT of chromatic aberration with these lenses. More than I ever did before with my previous polycarbonate lenses, although to be fair, my Rx back then was closer to -5.50.

    2) I really dislike the degree to which they minimize my eyes and distort the sides of my face. I know that the high (-) power and wide frames are partly to blame for this... but it is SEVERE (my head looks about 3" narrower through the lenses), which is why I suspect they may be spherical in design. I could be wrong, however.

    3) The AR coating, which I'd never had before, is very obviously green when outdoors or under fluorescent lighting. I've noticed the same thing with a friend of mine who has AR, but instead of just green it's a rainbow. This is annoying and distracting... plus, I still experience a decent amount of glare, and almost feel like I spent money for nothing.

    I now have a pair of full-rim plastic frames with a more-appropriate 46mm eyesize, and would like to try regular CR-39 lenses since I understand they are of superior optical quality and cause minimal chromatic aberration. These frames are rather solid and chunky, so the weight and thickness of CR-39 will not bother me. My main concerns are:

    1) I understand that aspheric lenses cause less distortion of the eyes and face than spherical lenses, but I can't find any reference to this when checking out the info pages for CR-39 lenses on various manufacturers' websites. I guess this information is considered too technical for inclusion on an infosheet designed for patients.

    Are CR-39 lenses commonly (or even at all) made in both spherical and aspheric designs? If so, who makes aspherics, and what are the brand names? And will they really improve the distortion, or is it mainly marketing?

    2) Since CR-39 reflects less light than high index, is the AR coating necessary? I guess I'm asking whether there'd be a significant difference between high index with AR vs. CR-39 without. I'd rather deal with a little extra glare than the weird colors.

    Any input or advice would be much appreciated!
    kal, Sep 16, 2011
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  2. kal


    Sep 18, 2011
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    If you don't mind the expense, a 1.67 aspheric lens with 1.0 center thickness and crizal anti glare should give you the best optics. Different anti glare brands give different reflections based on how many layers of coating are processed on the lenses. CR-39 may technically have better ABBE values (optical term) but any possible increase in clarity will be offset by the thickness of the lenses.
    eyedr1996, Sep 18, 2011
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  3. kal


    Aug 28, 2012
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    CR39 has no aspheric lenses.
    wearegood, Sep 7, 2012
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