It appears you have not yet Signed Up with our community. To Sign Up for free, please click here....

Eye & Vision Message Board

  • Methods of measuring myopis - confused!

  • Post New Thread   Closed Thread
    Thread Tools Search this Thread
    Old 02-11-2006, 11:24 PM   #1
    Foogoo's Avatar
    Join Date: Nov 2003
    Posts: 92
    Foogoo HB User
    Methods of measuring myopis - confused!

    I have been exposed of three different ways doctors measure myopia: the 20/xx, "minus xx", and xx degrees. How do these three convert to one another?

    For example, I am approximately 700 degrees. What does that mean on the 20/xx scale?

    Sponsors Lightbulb
    Old 02-12-2006, 05:13 AM   #2
    Senior Veteran
    twoeyez's Avatar
    Join Date: Jun 2005
    Location: Naples,FL
    Posts: 828
    twoeyez HB Usertwoeyez HB User
    Re: Methods of measuring myopis - confused!

    Myopia is commonly detected by reading a Snellen eye chart from a distance of 20 feet. Notations of 20/20, 20/30, or 20/200 are used to measure visual acuity. The Snellen method is adequate for screening purposes to determine visual acuity, but it does not accurately quantify myopia because there are other variables that affect an interpretation of the chart, such as squinting, guessing at blurred letters, and room lighting.

    The "power" of a lens placed in front of an eye to correct for myopia is measured in terms of diopters. The table below gives an approximate idea of the vision to expect with varying degrees of myopia:

    Myopic Correction and it's Snellen Visual Acuity :

    -0.50 20/25 to 20/30 -1.00 20/30 to 20/50 -3.00 20/300 -4.00 20/400 -5.00 20/600 -6.00 20/800 Therefore a -6.25 = approx. 20/850
    -6.75 = approx. 20/950. When you say you are 700 degrees,you are really saying your -7.00 Dioptors of Myopia. So that (as above) would make you approx. 20/1000.

    It is important to know your CORRECTED Snellen Visual Acuity IS 20/20. For example, if you have only 20/60 VA with the best possible CORRECTION, then you have VISION LOSS.

    Myopia when corrected to 20/20,with glasses or contacts, is always the important thing to consider.


    Last edited by twoeyez; 02-12-2006 at 05:27 AM.

    Closed Thread

    Related Topics
    Thread Thread Starter Board Replies Last Post
    Measuring behind schedule ibelieve Pregnancy 7 05-26-2007 11:02 AM
    measuring small...should I worry? lbp35 Pregnancy 2 08-18-2006 09:07 AM
    measuring 6 weeks behind Im_Robyn Pregnancy 5 06-03-2005 04:59 AM
    Need help with measuring progesterone cream... danigirl Menopause 1 04-22-2005 09:45 AM

    Thread Tools Search this Thread
    Search this Thread:

    Advanced Search

    Posting Rules
    You may not post new threads
    You may not post replies
    You may not post attachments
    You may not edit your posts

    BB code is On
    Smilies are On
    [IMG] code is Off
    HTML code is Off
    Trackbacks are Off
    Pingbacks are Off
    Refbacks are Off

    Sign Up Today!

    Ask our community of thousands of members your health questions, and learn from others experiences. Join the conversation!

    I want my free account

    All times are GMT -7. The time now is 08:06 PM.

    © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved.
    Do not copy or redistribute in any form!