Eyeglass Prescription – Understanding What it Means

You recently had your vision checked and were handed a prescription with numbers and abbreviations on it and wondered; “What does this mean?” The information is related to your eye exam and how your eyeglass lenses are to be manufactured and placed into your eyeglass frames. Let me clear up what this small piece of paper is saying. It is actually easier then reading an eye chart!

A common example of an eyeglass prescription for someone over 40 will have the following information:

OD -4.50 -1.00 X 160

OS -4.25 -1.50 X 175

Add +2.00

PD 63

Without having you take a course in optometry, let me explain in layman terms what this all means. First off, the OD and OS is Latin for oculus deter which means right eye and oculus sinister which means left eye. Now the number next to the letters OD or OS stand for you prescription strength in each of your eyes and technically they are called spherical power. It is common to have two different strengths of spherical power for each eye, therefore do not be alarmed if they are different numbers.

Now if you prescription number is a negative number, it just means that you are nearsighted. This means that you can see things close up, but you have a hard time focusing on things far away. The opposite is true if the number is a positive number, where you are farsighted and therefore have a hard time seeing things close up.

Not everyone has a prescription with the next column of numbers, but if you do, it basically relates to a blur that you have in your vision which is called an astigmatism. Although you may need glasses which have corrective powers to see things either far away or close up; your vision still can be blurred due to an abnormal curve in your cornea. It is this column of numbers that indicate the incremental amount of power, which is called cylinder power, that will correct the blur that is in your vision.

The last column of the numbers simply indicate on a scale of 0 to 180 degrees, where on your eye that you have the abnormal curve and where your eyeglass lenses need to be adjusted to correct the blur or astigmatism.

If you are over 40, it is common to have the next number, which is indicated after the word add. It is basically adding more power to you lens so you can read or see things up close. This condition is called presbyopia and happens to everyone after a certain age, usually around 40. Basically, the muscle in your eye is not accommodating for close up anymore . It is easily corrected with a multifocal prescription that you commonly know as a bifocal, trifocal or progressive lens.

The last item that you might see on your prescription is the letters PD with a number next to it. Again, this is very simple stuff, it stands for pupillary distance and the number represents the distance from the center of one eye to the center of the other eye, measured in millimeters. This number is important to know when selecting frames and centering your eyeglass lens within your frames.

Once you know what all of those numbers mean, understanding your eyeglass prescription seems pretty simple. Of course it takes years of education and practice to know the details behind creating your prescription. And the same holds true for carefully selecting eyeglass frames and making your eyeglasses work for your particular prescription and special facial features.

Many smart and thrifty consumers today are requesting their eyeglass prescriptions from their eyecare professional in order to take their time in the comfort of their home to shop for eyeglass frames online without feeling the pressure to have to make a quick selection.

If you are one of those types of people who is mindful of their budget and is looking for a large selection of frames, please visit us at www.Cheapglasses123.com where we are happy to answer all of your eyeglass questions and help you select the frames that work best for your eyes and facial appearance.

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