Advice, vdu glasses from reading prescription

Discussion in 'Glasses' started by Mr Edward, Oct 28, 2007.

  1. Mr Edward

    Mr Edward Guest

    I'm hoping for some advice to help me order a pair of specs for computer
    use from an online store. I've got a recent prescription for reading
    glasses that are great for focusing at around 35cm, but not very suitable
    for computer work:

    R -0.25/0.50X160 L +0.50/0.50X180 Add Near +1.75

    My script doesn't give a figure for 'inter', and as I want to make the
    order as fool proof as possible, I was going to order reading specs and
    adjust the 'add +1.75' to a lower power to make them suitable for use at
    around 100cm distance.

    Is there a rule of thumb I can apply to get the correct 'add' figure from
    what I've already got?. Hope my question makes sense.

    I'm 53 yrs, if it matters!
    Mr Edward, Oct 28, 2007
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  2. Mr Edward

    Mr Edward Guest

    Thank you for your reply....Yes you are right! I didn't measure it before,
    I was repeating what I thought the optician said and I must have made a
    mistake, sorry.

    OK Ive measured the range of clear focus and it's 44cm to 65cm when viewing
    my LCD screen, and curiously different at 34cm to 74cm when viewing the
    printed page. Is that normal?

    I should just add that these distances are measured with my current reading
    glasses with an add of +1.50. When I had an eye test 2 months ago the
    difference from my previous prescriptions was too small to warrant a new
    pair of specs. that's why I'm still using specs with a +1.50, I've had
    these specs for 5 years now bye the way (my first pair of reading glasses),
    and in all that time not enough change to warrant a new pair.

    My optician has told me I still have pretty good vision for my age.

    Any advice appreciated.
    Mr Edward, Oct 29, 2007
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  3. Mr Edward

    Mr Edward Guest

    Thank you for the advice, progressive sounds like a good idea. Just one
    clarification first please, on my prescription the CYL is +50 for both
    eyes, on the version you give above, have you adjusted this to -0.50 and
    -0.25, or is simply the shorthand way it's written?

    As you can tell I don't fully understand the prescription and the way that
    SPH and CYL appear to be able to be manipulated to end up with the same
    type of correction.

    Much appreciated.
    Mr Edward, Oct 29, 2007
  4. Mr Edward

    Mr Edward Guest

    OK thank you for your patience, before I place an order I need to be sure
    I'm not making any wrong assumptions. As always a little knowledge equals

    So should a progressive prescription look like this.

    R +050+050x160
    L +125+025x180
    add +1.00

    or like this

    R +050+050x160
    L +125+050x180
    add +1.00

    I can't see why the CYL for L became +025 from +050 on the original, if
    it's just part of the magic I'll accept that it should be. Sorry to have
    to ask again for clarification and I do appreciate your help.
    Mr Edward, Oct 29, 2007
  5. Mr Edward

    Mr Edward Guest

    A very clear explanation, thank you. I now understand why my first
    prescription expressed with -ve values, was actually the same as the next
    one even though the numbers are very differnt. The optician told me they
    were close enough, but without any explanations, now I get it!
    Mr Edward, Oct 29, 2007
  6. Mr Edward

    Mr Edward Guest

    That's great, thank you so much.
    With the help of Mrs Edward I've got a PD measurement of 66mm. I did read
    that with a mild prescription it's not so critical, though more so with
    progressives than single distance. I think 66 is reasonably accurate,
    whilst I'm focusing in the distance.

    I'm ready to order that well needed pair of specs which will stop either
    trying to read the screen without any, or having to get too close with them

    Thanks again for your patience and advice, much appreciated.
    Mr Edward, Oct 29, 2007
  7. Mr Edward

    Dan Abel Guest

    Well, perhaps not, except to rule out measurement error. The range of
    clear focus is always heavily dependent on illumination level. It
    shouldn't matter for LCD work, since that distance should be fixed,

    you try to read and look at the LCD in the same session.
    Dan Abel, Oct 29, 2007
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