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How to Read Eye Prescription

How to Read Eye Prescription

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3 min read

Your prescription has a lot of numbers and abbreviations.

you don’t know what it means. but knowing these will help you understand your eye condition.

and it also helps you to buy prescription eyeglasses online.

let’s take a look at important abbreviations in prescription mean.

OD(right), OS(left)

The OD and OS are from the Latin language as right and left.

Usually, prescriptions are written horizontally. with OD(right) on the top line, OS(left) on the second line


The SPH is the mean of the sphere, which comes from the geometry of lenses.

if there are minus signs in the front of the number, that means nearsighted. if there is plus sign or no sign in front of the number, that means farsighted. the number as low as power is weak. usually, it will be between -6.00 to + 6.00, and if there is “Plano” or “N/A”, that means you don’t have to correct in this eye.


The CYL means cylinder, Which indicates you need astigmatism correction. this is because part of the cornea has a different curve, and the eye shape is not spherical. It’s like an egg, this will cause your farsighted and nearsighted to blur. Usually, it’s -2.00 to +2.00

The cylinder appears when you are born. usually, it will with farsighted or nearsighted. if you don’t have a number in this column, then you don’t have to correct astigmatism in this eye.


The AIXS always goes with CYL, you can’t have AXIS without CYL. The cylinder is like a concave line through the lens, the AXIS is this line direction.
if AXIS is 90 and then the line is vertical if the axis is 180 and the line is horizontal. It must be between 0 to 180. remember, if you have the CYL number, that must have the AXIS number

ADD(addition magnification)

ADD means addition magnification. to add magnification in the bottom area of lenses. that is only for the progressive or bifocal lens, the ADD number in the most of prescriptions is empty.
When you see a near thing, like reading, your eyes will look downside. the ADD number is the added magnification of your lens on the bottom area. That will elevate your eye pressure of looking near things. usually, it's between 0 to +3.00

PD(pupillary distance)

PD means pupillary distance. Most optometrists will not write this number in the prescription. it's to avoid competition from online glasses sellers. So if you need to buy prescription eyeglasses online, you will need this number. don’t worry, you can measure your pd from our app. It needs a newer iPhone.

Above are all the important abbreviations in your prescription you need to understand. and there have other things in your prescription. like expiration date, doctor's name, and your name, it depends on the doctor.

If you still have any questions about your prescription. please send an email to we are happy to help you.