High index lenses

Discussion in 'Optometry Archives' started by J North, Feb 28, 2004.

  1. J North

    J North Guest

    Hi there!
    Ref: High index lenses

    I've had very vague responses from high street opticians on this stuff
    and would very much appreciate any advice you can offer on the topic.
    Apologies for length but the more info the better seamed appropriate
    here.

    After a cataract removal op some years ago and am now left with no
    internal lenses. (Too long a tale to go into here.)
    I use contact lenses of power +18 and +19.5 for daily site.
    These lenses have made a tremendous difference to my quality of life
    and I can't thank the NHS UK consultants and associated support staff
    enough. I see them on a regular basis and they couldn't be more
    helpful.

    However as I can only wear these lenses approx 12 hrs per day I rely
    on a pair of high index spectacles I had commissioned for the
    remaining part of the day.

    I've had these now for over 7 years and am sure better (higher index)
    materials are available now.
    I don't know the index of the (plastic) lenses I have, as they were an
    impulse buy in Cyprus (another long story) but they are much thinner
    than my original pair.
    I really would like to get lighter and thinner lenses as they do cause
    me problems. However I am a realist and know they will still be quite
    thick, but any improvement is a good thing and I strive to minimise
    the effect this has on my lifestyle. I believe the further away from
    the eye the lens is the lower the power required. I think this makes
    my spectacle lenses about +12 to +14 ish (I can obviously get that
    checked)

    I assume the thinnest design would be an aspheric lens but I haven't
    seen any details of these lenses at this high power. I also assume
    that plastic lenses would be better as they are lighter.
    There appears to be several main manufacturers of high index lenses,
    the best I could find are listed below: Can anyone point me in the
    right direction here please and if possible a high street optician in
    the NE of England who could cater for such a specialist job.

    Regards John

    ZEISS
    http://www.zeiss.de/4125680F0053A38D/?Open

    Lantal 1.9 - index of 1.893
    (high myopia from -8.00 D to -16.00 D )
    Comments:
    They appear to be only for myopia and not for + powers -.Hyperopia (I
    think)
    They are also glass and I assume they would be heavier than plastic.

    Clarlet 1.74 AS (index of 1.74)
    Comments:
    They appear to be only for myopia

    Clarlet 1.67 AS
    Comments:
    Appears to be for both – and + power but maybe only to +8

    Kodak
    http://www.kodaklens.co.uk/lens-thinlite.asp
    1.67 - Kodak ultra thin & lite lenses
    Comments:
    They appear to be suitable

    Nikon
    http://www.nikon.co.jp/main/eng/products/glasses.htm
    Nikon Lite IV-AS HCC

    Comments:
    Couldn't find any data on these but I think Dollond and Aitchison sell
    them
    http://www.danda.co.uk/html/eye_wear/lens4.asp

    Their brochure says they are the thinnest lenses you can get.
     
    J North, Feb 28, 2004
    #1
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  2. Hi John

    The major problem for yourself and any aphakic ( cataract operation without
    implant) is that
    there arn't many of you about now. Consequently the maunfacturers are not
    producing lenses
    with your prescription in any numbers.
    Your spectacle prescription will be different to your contact lens
    correction and given the figures you
    give should be in the +15.00 range.

    A quick look through Norvilles catalogue ( major independant supplier of
    spetacles lenses) show that
    the Seiko SSV 1.67 aspheric (plastic) may be suitable.
    You could always go for standard plastic lenticulars or Omega Aspheric in
    CR39.
    Regarding High Index most of the lenses cut off at +10.00.

    Without your spectacle prescription it is very difficult to advise you. Also
    please note
    that the nature of any spectacle frame you decided on will have a major
    effect on
    the lenses selected.

    Regards


    Ian Hodgson - Isle of Man
     
    Ian Hodgson Opticians Ltd, Mar 1, 2004
    #2
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  3. J North

    John Guest

    Its about 7 years now since I bought my glasses.
    Is it possible they are CR39 already?

    You mention Seiko SSV 1.67 aspheric would they be thinner than CR39.
    I don't know much about aspheric technology but I had assumed they didn't go
    as high as +15.
    Also I see the 1.67 - Kodak ultra thin & lite lenses are the same index
    would they be as suitable or not.

    http://www.kodaklens.co.uk/lens-thinlite.asp

    Thanks very much for the info, I do appreciate your reply.

    Regards John
     
    John, Mar 1, 2004
    #3
  4. John,
    The problem is less the refractive index ( 1.67 or 1.8 etc) but the
    thickness of the blank
    that is the maufacturer uses to make the final prescription. In the case of
    Kodak lenses they
    do not surface above +8.00 sphere, and here in lies the problem. Most lens
    blanks do not have
    the substance ( ie thickness) to be worked above +8.00 in fact a lot of
    manufacturers
    will NOT surface above +6.00sphere.

    If your lenses are about 7 years old then, if plastic, it is probable that
    they are CR39.

    Without your proper spectacle prescription and given that you are aphakic
    then it should
    not have changed over time advice on the lens type is virtually impossible.

    My best suggestion is go to opticians in your area ask to either see the
    Optometrist or
    the dispenser (check to see if they are FBDO) and see if they are willing to
    go through
    the lens catalogues for you. If they say it can't be done or they cannot be
    bothered then walk out.
    Without full details and an idea of the type of frame you want it is
    difficult even more so over the net.

    Regards


    Ian Hodgson - Isle of Man
     
    Ian Hodgson Opticians Ltd, Mar 1, 2004
    #4
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