Understanding Your Glasses Prescription: What the Numbers Mean
In a typical prescription (like the one above), you’ll find these abbreviations on the left side: O.D. This is short for oculus dexter, and is your right eye. O.S. This is short for oculus sinister, and is your left eye. Apr 13, · ADD stands for the additional lens power needed to make it easier for you to read. This number is seen on prescriptions for reading glasses or .
We know these as the instructions for making your glasses, but what do prescriprion actually mean? The sphere column is often abbreviated as SPH. This is the lens power needed to fix your vision. Think of the measuring system as an integer number line, with zero in the middle needing no correction.
The further away you get from the zero on either the minus or plus side, the stronger your prescription is. The cylinder number is how much what are the main causes of homelessness in america you have, if any.
This is when part of the cornea has a different curve. Normally, an eye is shaped like a basketball—rotated any direction, the curve stays the same. An eye with astigmatism is more like a football—one curve is longer than the other.
The CYL number corrects this different second curve. This number tells you where the astigmatism is on the cornea. Frwmes axis—written in degrees between 1 and —indicates which way the astigmatism lines up. There is where any additional lens powers are written. They choose to wear bifocals instead. The lower half of the lens gives them their reading vision.
There may be a field for prism on the right side not pictured. This is a special type of correction built into the lens for some people with double vision seeing two separate images of the same object.
The prism fuses the two images together so only one image is seen. Because contacts sit directly on the eye, the prescription is different than one for eyeglasses.
A contact how to develop slide film prescription includes measurements specific to the size prescripgion brand of your contacts.
About Foundation Museum of the Eye. How to Read an Eyeglasses Prescription. Written By: Daniel Porter. This is short for oculus dexter, and is your right eye O. Trial lenses used for checking a person's glasses prescription. What is an Ophthalmologist? Eye Screening for Children. Find an Ophthalmologist. Advanced Search.
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How to Read Eyeglasses Prescriptions When you look at a standard prescription, the first word you'll see is "Distance." This term refers to what power of lens you will need to see distant objects clearly. Your ophthalmologist or optometrist determines this power by trying different lenses while you read an eye chart in the exam. Progressive / Bifocal. For multi-focal glasses, as well as reading and computer glasses, your Rx will include an ADD or NV value. This number always has a (+) sign. Rx Note: The type of Rx glasses may be noted on a prescription, such as DV [Distance Vision/nearsightedness] and NV [Near Vision/reading]. The first step to understanding your eyeglass prescription is knowing what "OD" and OS" mean. They are abbreviations for oculus dexter and oculus sinister, which are Latin terms for "right eye" and "left eye." Your eyeglass prescription also may have a column labeled "OU.".
Last Updated: September 30, References. This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness.
There are 15 references cited in this article, which can be found at the bottom of the page. This article has been viewed 28, times. Learn more To read an eyeglass prescription, look for the labels "O. If you're near-sighted or far-sighted, check the "SPH" column to find out how strong your lenses need to be. Additionally, read the "CYL" column to find the strength of lens you need to correct astigmatism. You should also look for the "Add" row if you need both near and far-sighted corrections.
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Look for O. The numbers represent diopters, a unit of measurement used to describe the corrective strength of a lens. Astigmatism is a blurring of the vision caused by an irregularity of the lens or cornea. The axis column contains a number that corresponds to the angle of your astigmatism.
On some prescriptions, there may be no axis column. Instead, the axis may be preceded by an x and written right after the cylindrical measurement e. If your eyes need both near vision and distance vision correction, your prescription will have two rows of spherical corrections.
The base column indicates the location of the prism on the lens, i. Method 2 of Your pupillary distance P. The optician who crafts your lenses needs this information in order to position the optical center of your glasses correctly. While your vision provider is not required by law to release your P. Buy or print out a pupillary distance ruler for a simple DIY measurement. Buy a straight edge or digital P. You can also measure your P.
Measure your own pupillary distance with a P. To measure your P. Close your left eye, and read the number on the ruler directly over your right pupil. Reverse the process to find the measurement for your left pupil. Add the two numbers together for the total distance. If your P. If you use a regular ruler, place the 0 mm mark directly over your right pupil, and measure from there to the number directly over your left pupil.
Get a friend to measure your P. Have them crouch just below your field of vision, and focus on something ft. Moving your eyes or focusing on your friend will skew your results. Use a pupillary distance app for a quick and easy digital measurement. If you have a smartphone with a camera, you can get a reading of your pupillary distance with an app like PD Meter by GlassifyMe. Many online glasses retailers, such as Warby Parker and FinestGlasses. Note that this method may produce inaccurate results, since it forces you to focus on a close-up target your phone camera or computer screen.
Your pupillary distance becomes narrower when you are looking at something close-up. Measure your P. With your current pair of glasses on, focus on an object in the distance, at least 20 ft 6 meters away. Close your left eye, and use a washable felt-tipped marker to place a dot on your right lens so that it directly covers the object you are focusing on. Close your right eye, and repeat on your left lens.
Then, measure the distance between the two dots in millimeters. Include your email address to get a message when this question is answered. In the US and UK, your vision provider is required by law to give you a copy of your prescription, free of charge. Helpful 0 Not Helpful 0. Contact lenses are constructed differently, so the measurements will not be the same.
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Co-authored by:. Co-authors: 4. Updated: September 30, Categories: Eyeglasses. Article Summary X To read an eyeglass prescription, look for the labels "O. Thanks to all authors for creating a page that has been read 28, times.