Understanding Your Eyeglass Prescription
Understanding Your Eyeglass Prescription with 20/20 Vision
Congratulations! You have made it through your eye exam and as a reward you were given a piece of paper which surely must mean something important. Something possibly life changing, but when you look at it all you see is an elaborate collection of abbreviations and numbers.Where’s the 20/20? Who is OU? What you are looking at is your eyeglass prescription. It may seem incomprehensible at first, but with a little explanation, you will find it isn’t that crazy after all.
Why So Complicated?
Eyeglass prescriptions are not intended to be complicated. Actually, they are designed to simplify the process of correcting vision. All the abbreviations and numbers you see are just a way to standardize how eye professionals communicate, so that both doctors and patients have a universal language devoted to giving you better vision. The prescription is meant to describe intervention for astigmatism, nearsightedness, and farsightedness, so it needs to be comprehensive, but not impossible to understand.
Once you understand what’s written on your prescription, tracking how your vision is changing in between appointments becomes much easier. It is the best way to know immediately if all that screen time you are logging will result in new glasses or not. If your eyesight is deteriorating, your prescription can give you important clues as to which interventions are working and which are not.
The Most Common Eyeglass Prescription Abbreviations and Terms
Your eyeglass prescription contains many abbreviations and terms. Here are a few of the most commonly used and why they are important to know.
OD – Oculus Dexter, or right eye. Also seen as RE (right eye).
OS – Oculus Sinister, or left eye. Also seen as LE (left eye).
OU – Oculus Uturque, or both eyes.
D – Diopters, a unit of measurement.
SPH – Sphere. The amount of correction measured in Diopters (D).
CYL – Cylinder. The amount of lens power for astigmatism.
AXIS – The lens meridian with no power. Used for astigmatism.
ADD – Additional magnification for the lower part of a multi-focus lens.
PRISM – Prismatic power prescribed for alignment problems.
BU – Base up prism orientation
BD – Base down prism orientation
Putting the Terms to Use
Putting them all together results in something that looks like this:
OD -3.00 SPH +1.00 add 0.25 p.d BD
OS -2.00 -0.25 x 180 +3.00 add 0.25 p.d. BU
Using the definitions above, this jumble of letters and numbers quickly takes on a new meaning. The right eye (OD) requires -3.00 sphere correction. There is no astigmatism, so there is no axis value. Further, additional power is being added to the lower part of the lens in a prism down orientation.
The OS, or left eye, requires a little more complicated prescription. First, a sphere correction of -2.00 is needed. Then, an astigmatism is addressed with a 0.25 cylinder correction at 180 degrees. Finally, the lower part of the lens is magnified by 0.25 in a base down (BD) orientation. You may not understand why everything is on the eyeglass prescription, but you can at least know if all that Vitamin A you’ve been taking is having a positive effect. Most likely, your eyecare professional will go over the numbers with you at your appointment. If not, it’s possibly time to ask more questions or seek out a different provider.
Although treatment of your vision can be a complicated process depending on your issues, reading your eyeglass prescription doesn’t have to be. It is there to make the process easier, and once you understand the language, you will become an active participant in your plan for better vision.
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