how do you read a contact lens perscription

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od: -450-075 x100
 os: -400-075 x070

what does this mean ?
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kaos_theoryAsked:
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TK-77Commented:
This site has an interactive table that will explain all of the contact prescription info.
http://www.allaboutvision.com/contacts/contact-lens-rx.htm

TK
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nickg5Commented:
here's another:
http://www.usaeyes.org/lasik/faq/read-eyeglasses-contacts-prescription.htm
OD = right eye and OS = left eye.
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aleghartCommented:
od  |  -450  |  -075  |  x100
(od) right eye
(-450) refractive error measurement: -4.50 sphere or diopter = near-sighted, approximately  20/300 vision; you can see at 20 feet what others can see from 315 feet away.
(-075) astigmatism measurement: -0.75 cylinder
(x100) axis measurement: location of the astigmatism...no correlation to degree of correction, just where the correction needs to be

os  |  -400  |  -075  |  x070
(os) left eye
(-400) refractive error measurement: -4.50 sphere or diopter = near-sighted, approximately  20/300 vision; you can see from 20 feet what other people can see from over 280 feet away
(-075) astigmatism measurement: -0.75 cylinder
(x070) axis measurement: location of the astigmatism...no correlation to degree of correction, just where the correction needs to be


So, in summary, you are nearsighted (myopic) to the point that you can only read clearly from about 9 inches away.  (1/4.50)=.222m=8.7in.

You have astigmatism in both eyes...which means that your eyeball varies from spherical, like a bump or a depression.  In some people, depending on location and severity of the variation, darkness will cause the iris to open up and expose some of the irregularity, causing distortion.

Hope this helps.  I've had myopia ranging from -4.50 to -5.25 diopters...great for proofing film on a light table without using a loupe.  But...terrible for navigating a SeaDoo at 60mph when one contact is blown out of your eye.  :)
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