Understanding difference between new & old prescriptions

Discussion in 'Optometry Archives' started by newsbirdie2, Feb 21, 2008.

  1. newsbirdie2

    newsbirdie2 Guest

    Glasses and optics have always intrigued me (should have been an
    optometrist) so I'm hoping to get some insight on my prescriptions.

    Dr. #1 : January 2003

    +0.25 (+0.25 10 degrees)
    +0.25 (+0.25 170 degrees)

    I didn't get these. She said not to unless I really needed them.

    Dr. #2 - November 2005

    +0.00 (+0.25 50 degrees)
    -0.25 (+0.25 140 degrees)

    She commented that my astigmatism was very unusual and explained why
    but of course I didn't understand. I got the glasses (first time I've
    ever had glasses) and they helped but I guess I really didn't need
    them cause after a few weeks I stopped using them.

    Dr. #1 (same Dr. as 2003) - February 2008

    +0.50 (-0.25 110 degrees)
    +0.50 (-0.25 70 degrees)

    I had been having blurry vision (I work at the computer all day) for
    the past 2-3 months and it was finally bothering me. She said my eyes
    haven't changed since the last time she saw me (2003) but my ability
    to focus my eyes is weaker and that this time I should get the
    glasses. I didn't mention the fact that I saw Dr. #2 since my last

    I got the glasses and they help a lot. The text on my monitor is
    crystal clear. I've been wearing them since I got them, about a week
    now. Today I tried on my old glasses for the first time since getting
    the new ones. I see better with them (I'm comparing them while
    reading text on the computer) than without, but in my opinion the text
    isn't as crisp as it is with my new glasses. So then I started
    googling. I found out that Dr. 1's new prescription is basically the
    same as her old one, with the axis changing slightly (10 degrees for
    both eyes).

    The first question is what is the tolerance of error for determining
    the axis? Do eyes change 10 degrees over 4 years?

    The next question is how did Dr. #2 have totally different axis? I
    would think that if the axis were off by 20-30 degrees it would make a
    big difference. Or maybe my eyes have changed a lot each 2 years?
    Unlikely that he'd change and then go back to the way they were

    Which leads to the third question: Why did Dr. #1 give me a slight
    magnification (+0.25) while Dr. #2 gave me 0? I only use the glasses
    for reading and the computer so I think the magnification is good

    And final question, can I still wear my old glasses? I use my new
    ones for the majority of the time but it'd be nice to have my old ones
    by my bed for bedtime reading, or for a backup. I don't want to use
    the old ones if it's bad for my eyes.

    Thanks for the help in clarifying these prescriptions.
    newsbirdie2, Feb 21, 2008
  2. newsbirdie2

    Mark A Guest

    The magnification (sphere in this case) is measured to the nearest .25
    diopter. Sometimes people are on the border, and/or it just depends on how
    tired your eyes are during the exam, you general health, or how accurately
    you answered the exam questions (which is better: 1 or 2) when you got your
    eye exam. In some cases it may also depend on how careful the OD is when
    giving the exam.
    As long as you can see clearly, it will not hurt your eyes to wear your old
    Mark A, Feb 21, 2008
  3. newsbirdie2

    newsbirdie2 Guest

    As long as you can see clearly, it will not hurt your eyes to wear your old
    Thanks for your answers. Hopefully someone can tackle the other two

    A follow-up question: If the glasses for astigmatism for x degrees,
    what would be the opposite, and if I wear the opposite would I notice
    anything? (Put another way, if the glasses are the opposite of what I
    need, would they then be the same as my eyes and therefore make no
    newsbirdie2, Feb 21, 2008
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