You had an eye test and received a prescription with some crazy abbreviations and numbers on it. Now, you must be wondering how to read prescription glasses. What do abbreviated terms like OS, OD, CYL, and SPH mean?
With this article, we will help you untangle all ingredients of the received prescription and be able to talk about it with an optician before buying eyeglasses.
Along with this, we will share some fine examples of prescriptions, so you learn how to read a prescription for detailed understanding.
Let’s begin with the first terms you will come across while reading a prescription for your glasses.
What Do OD And OS Imply?
OD stands for Oculus Dexter, which is a Latin term for the right eye. And OS stands for Oculus Sinister, which is a Latin term for the left eye.
Your prescription may also include a word titled “OU.” OU is the short form for the Latin phrase Oculus Uterque, which implies “both eyes.”
The usage of these shortened Latin phrases is conventional for prescriptions drawn for glasses, contact lenses, and eye medications.
But instead of OD and OS, some eye specialists and infirmaries modernize their prescriptions by using LE for the left eye and LR for the right eye.
Also, you will notice this one more conventional habit of writing eyeglass prescriptions wherein the data about your right eye (OD) succeeds the data of your left eye (OS).
It is usually written like that because when you have face-to-face contact with your optician, your right eye is on the left (first) and your left eye is on the right (second).
Now, let us move further and get to know about other abbreviations on your prescription for eyeglasses.
How To Read Vision Prescription By Deciphering Abbreviations and Numbers?
Your prescription slip may include the following acronyms and words as well. These are:
- Sphere (SPH)
Sphere or SPH implies the proportion of lens ability, calculated in diopters. It prescribes your ability to see things near or far.
How to read a prescription to assess lens ability?
When the number happens to be under the title of a minus sign (–), you have Nearsightedness or Myopia. If the number occurs to be a plus figure (+) or does not proceed by a plus or a minus sign, you have Farsightedness or Hyperopia.
- Cylinder (CYL)
The cylinder or CYL explains the ‘cylinder’ part, which assesses the extent of astigmatism power. Also, it represents the disparity in curvature and strength between two eye points, divided by 90°.
How to read an Astigmatism prescription?
The value written right after the sphere one in a prescription is your astigmatism prescription. When the value in the column is equal to zero, either you have no astigmatism, or the power of astigmatism happens to be so small that it does not need correcting with eyeglasses or lenses.
But when the value in the column precedes a minus sign, then you have nearsighted astigmatism. Also, when the power has a plus sign, you have farsighted astigmatism.
The Axis value will range between 1° to 180°, which is extremely useful in rectifying astigmatism. However, to reduce mistakes, the doctors write the axis value as three digits. For example, an axis quantity of 65 is 065.
Furthermore, when an eyeglass prescription comprises cylinder power, it also includes the value of the axis. Contrarily, when it does not have any cylinder power, then there will be no axis value.
Note: When doctors write freehandedly, the axis figure comes after an X sign.
- ADD Number
ADD gives patients a positive vision at a considerable range for near-point and reading activities. Generally, this value is nonexistent in adolescent eyeglass prescriptions. Yet, some adolescents still can develop near-focusing issues and may need an ADD power.
How to read prescription glasses related to multifocal lenses?
ADD is the strong magnifying power that you can apply to the bottom part of Bifocal, multifocal and progressive lenses to correct presbyopia. The amount in this prescription category is always in plus value. It varies from +0.75 to +3.00 D. Remember, that is similar for both eyes.
A small proportion of prescriptions for eyeglasses constitute a prism. Its value usually prescribes displaced images in a specific path for patients having Strabismus or crossed-eye. They may also have trouble focusing or eye muscle disorders.
The amount of prismatic power is in prism diopters (p.d.). Your optician can also write it as a superscript triangle that compensates for eye alignment difficulties.
How to read prism prescriptions?
The prismatic power does not have (+) or (-) signs. In the case of the prism presence, the base direction of the prism (the heaviest edge) also gets depicted. Otherwise, it is nil or blank.
Shortened words for prism direction include:
BD = base down
BU = base up
BI = base in (toward the nose)
BO = base out (toward the ear).
You may have both vertical (BU or BD) and horizontal (BI or BO) prisms.
Other Common Abbreviations That May Appear On Your Glasses Prescription
Balance shows nil values, which notifies that the user needs the lens of identical weight to equalize the frame.
- Plano, Infinity, y 0.00, 0.00
These values show that your eyes need no correction for the particular part of the prescription where it is written.
- Inter, Inter Add, Int, Int Add, Intermediate Addition
These all pertain to intermediate addition. And doctors use it to carve glasses useful for moderate distance use. You can find them written anywhere on the slip.
- VA or Visual Acuities
This number describes your visual sensitiveness. But you need not correct it by wearing glasses.
Back Vertex Distance is the length needed from the cornea to the rear ground of the corrective lens.
Other Essential Comments
There is an area where the doctors write more recommendations. They usually specify Near-vision only (NVO) or eyeglasses used for a particular task like computer or music work.
It may include recommendations about specifying the lens, Photochromic/ Light Adjusting lenses, anti-reflective lenses, or the category of progressive lenses.
How To Read Glasses Prescription On Frames?
When you look inside your glasses, you will see a number written like 52 18 135.
This data indicates the length of your glasses, which could include bridge width, lens diameter, and side length. All are in the measurement of millimeters. Let us read all three in detail.
- Bridge Width is the division above the nose between the lens. Your eyeglass needs to be comfortable unless they may pinch your nose. Now, when it is too loose, they would not fit on your face.
- Lens Diameter is the lens width measured from the bridge. Generally, the size of lenses is a personal choice, but you can also determine your frame style and prescription.
- Side Length ranges within three standards – 135, 140, or 145mm. The side of the eyeglass should be such that it sits above your ears comfortably.
Now, if you are still searching on how to read spectacle prescriptions, here comes the part of the article that helps you to understand things better.
How To Read My Prescription For Glasses?
Suppose, if you see a minus sign, it states nearsightedness. Or, if you observe a plus, it signifies farsightedness. When you find an ADD power, it says you need magnifying lenses like progressives.
So, when you buy eyeglasses online, make sure the figures on your prescription correspond to the figures in the prescription field given online.
For example, your eye prescription is like -2.00 +1.50 x 180
This prescription implies that you need -2 diopters to correct nearsightedness and 1.5 diopters to correct astigmatism. Also, the axis value is 180°.
Another example your prescription can be +3.50 +3.00 x 45
That implies that you require 3.5 diopters to correct farsightedness, 3 diopters to correct astigmatism. And the axis value is 45°.
Hope you cleared all your doubts through these examples.
Going over an eyeglass prescription can be mystifying enough. Yet, with some research and analysis, you will become capable of reading eyeglass prescriptions like a pro.
We hope all your questions about how to read prescription glasses are answered now. Did you find this article helpful? Let us know in the comments below.