The 411 on reading kid's eye prescriptions

If this is your first time with a child in glasses, you may not know where to start, let alone how to read a prescription for glasses. It may feel intimidating, but don't worry! It's actually easier than you might think to read a prescription. Follow our how-to guide below and you'll be a prescription-reading guru in no time.

Sample of kids eye prescription from doctor

Sample of kids eye prescription



OD: This is a Latin abbreviation for oculus dextrus, which means your right eye. This eye is always listed first on the prescription.

OS: This is a Latin abbreviation for oculus sinister, which means your left eye. This eye is always listed second on the prescription.


From left to right on the top row of the prescription you will always find SPH, CYL, and AXIS. NOTE: There may not be a value entered for these categories. If this is the case, there is no correction needed for that eye!

-- SPHERE (SPH) --

What is SPH in a Glasses Prescription?

SPH stands for spherical power and describes the degree of nearsightedness or farsightedness.

A positive value, or a prescription with a plus-sign (+), means that your child is farsighted. If you see a negative value (-) that means your child is nearsighted.

In general, the further away from zero the number on your child's prescription, the worse your child's eyesight and the more vision correction they need.

The higher the number (ignoring the plus or minus), the stronger the prescription.


Cylinder is the measure of astigmatism, which means that the front of the eye does not have a perfectly round shape. It is very common to have an astigmatism! According to Eyecare Business, it is estimated that about "70 percent of all Rx’s written in the U.S. include astigmatism correction".

A person with astigmatism does not see clearly either at distance or at near which can result in blurry vision & results oftentimes with headaches.

For some prescriptions there will be no astigmatism correction for one or both eyes. Your eye doctor may just write the sphere power alone, or may use abbreviations like SPH (“sphere”) or DS (“diopters sphere”).

Please note : often times MDs use plus (+) and ODs use minus (-) for the CYL value. So if you see a plus (+) in the CYL value this means that a conversion needs to take place and the SPH and AXIS values will be affected - nothing to worry about as we will do this for you but we just like to state this so parents can get a good understanding.

-- AXIS --

If you do have a CYL number you will also have an axis number.

The axis indicates the orientation of astigmatism, measured in degrees from 1 to 180.


To the right of AXIS you may find ADD, PRISM, and P.D.

ADD stands for addition and is used with multifocal lenses (ie bifocals). If your child needs bifocals, you will likely see a number here. ADD is additional magnification which helps with vision at close range. Unfortunately, we cannot fill prescriptions that require a bifocal. If you see this on your prescription, please contact us at and we will make a recommendation for you.

PRISM is used to help people with muscular imbalance in their eyes. Prism helps to reduce eyestrain and correct double vision.

Please note : We are able to fill prism within a certain range however, there is an additional fee for prescriptions that require a prism. Our team will contact you directly if this is listed on your child's prescription.

P.D., or Pupillary Distance, is the distance between the centers of the pupils, which is used to position the lenses in frames. A PD measurement is required for us to fill your prescription order.

If you do not see a PD listed on your child's prescription, simply ask your optician; they should have your PD on file. Or you can also learn how to measure pupillary distance yourself using our resources and easy measuring tool.

Pupil distance can be measured in two ways:

Binocular which is a pupil-to-pupil measurement, this type of measurement will be between 42-60 mm for most children.

Monocular which is a per-eye measurement from the pupil to the middle of the face - example : 25/24.5 - the first number (25) is for the right eye (O.D.) and the second number (24.5) is for the left eye (O.S.) - total these together to get 49.5 binocular.


Unfortunately, we are legally NOT allowed to fill a prescription that is past its expiration date. For us to proceed with your order, we highly recommend making an appointment with the eye doctor so they can issue a new prescription, OR reaching out to your eye doctor to see if they are willing to offer a written extension of the prescription. We would need to have that written extension on file before proceeding with your order.

Some prescriptions do not have an expiration date listed. If that is the case, you can refer to the list below to determine the length of prescription validity past the issue date based on the state you live in!

Prescription expires 1 year after date of issue:

Alabama (AL), Alaska (AK), Arizona (AZ), Arkansas (AK), Colorado (CO), Connecticut (CT), Delaware (DE), Georgia (GA), Hawaii (HI), Idaho (ID), Illinois (IL), Indiana (IN), Kansas (KS), Kentucky (KY), Massachusetts (MA), Michigan (MI), Missouri (MO), Montana (MT), Nebraska (NE), Nevada (NV), New Hampshire (NH), New York (NY), North Carolina (NC), North Dakota (ND), Ohio (OH), Oklahoma (OK), Oregon (OR), Pennsylvania (PA), Rhode Island (RI), South Carolina (SC), South Dakota (SD), Tennessee (TN), Texas (TX), Vermont (VT), Virginia (VA), West Virginia (WV), Wisconsin (WI), Wyoming (WY)

Prescription expires 18 months after date of issue:

Iowa (IA), Louisiana (LA)

Prescription expires 2 years after date of issue:

California (CA), Florida (FL), Maine (ME), Maryland (MD), Minnesota (MN), Mississippi (MS), New Jersey (NJ), New Mexico (NM), Utah (UT), Washington (WA)


Still have questions on how to read an eye prescription? Email and we'd be happy to help!