How to Read Eye Prescription: A Complete Guide

Apr 08, 2021 06:00 AM

How to Read Eye Prescription - Photo by Andrea Piacquadio from Pexels
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Tripboba.com - If you look closely at your eyeglass prescription, you may wonder how to read eye prescription that is full of numbers and symbols. Basically, eye prescriptions are written in a standardized format using Latin abbreviations. But nowadays, some doctors and clinics have modernized eyeglass prescriptions using English terms.

If you are holding your eye prescription and curious about how to read eye prescription, you'd come to the right place. In this article, we're going to explain to you the detailed information on how to read eye prescription. We will start with the common abbreviations in eye prescription first. Keep reading!

How to Read an Eye Prescription

How to Read Eye Prescription - Photo by Andrea Piacquadio from Pexels

When you have just had an eye exam and you got the eyeglass prescription, you may be confused about what do the numbers mean. Before you learn to read how to read eye prescription, the first step to do is to understand the abbreviations in your eyeglass prescription.

You have first to know what OD and OS mean. So, the OS is an abbreviation of Oculus Sinister that means the left eye. While the OD is Oculus dextrous which means the right eye.

You may also find a column labeled "OU". This is the abbreviation for the Latin term Oculus Uterque which means something involving both eyes. However, some doctors and clinics sometimes use RE (Right Eye and LE (Left Eye.

Another abbreviation is SPH (Sphere of the Eye that refers to the lens's ability to refract light. CYL (Cylinder of the Eye or also means correction number needed for astigmatism. It means the cornea in front of the eye is misshapen or the lens at the back of the eye does not curve and change the direction of light. This condition will result in blurred vision if it is not corrected with prescription glasses. 

Besides, you may also see Diopters. It means the measurement units used to determine the optical power of the lens. The bigger number of SPH indicated the more astigmatism you have.

Astigmatism is often caused by a cornea that is shaped more like a football than a basketball. There is also Axis, a number that describes the place in the eye where astigmatism or difference in refraction is. The number ranges between 0 and 180 degrees with 90 being the vertical location line in the eye and 180 the horizontal one.

Now let's continue to the example of eye prescription and we'll teach you how to read eye prescription in detail.

How to Read Your Eye Prescription

How to Read Eye Prescription - Photo by fauxels from Pexels

Now after you understand many abbreviations in your eyeglass prescription, let's learn how to read eye prescription from the example below.

OD -2.00 SPH +2.00 add 0.5 p.d. BD

OS -1.00 -0.50 x 180 +2.00 add 0.5 p.d. BU

From this case, your doctor prescribes OD -2.00 for the correction of myopia in your right eyes. There is no astigmatism correction for your right eyes, so no axis is noted. Then for left eyes indicated by OS is being prescribed -1.00 for myopia and -0.50 cylinder for astigmatism correction.

While the cylinder power or axis is at  180 meridians. It means the meridian of the eye has no added power for astigmatism and the vertical (90-degree) meridian gets the added -0.50. Besides an add power of +2.00 is being prescribed for the correction of presbyopia in both eyes.

How to Read My Eye Prescription

To make you understand more how to read eye prescription, we will give you another eye prescription example and an explanation of it. Read carefully the way on how to read eye prescription below.

Example:

  • OD: -2.00 – 0.50 x 180
  • OS: +1.00 DS
  • ADD: +1.75 OU

In this case, we see the first number of the right of OD is -2.00. This refers to the "sphere" part of the prescription. The sphere numbers indicated nearsightedness or farsightedness. A sign of minus (- means a negative-powered lens that is used to correct nearsightedness. While the positive sign (+ indicates a positive -powered lens that correct farsightedness.

Still, in OD, the next number is – 0.50. This represents the "cylinder" that measures the degree of astigmatism. Then x 180 means Axis 180. It refers to the angle in degrees from 0 to 180.

For the left eye, the "sphere" number is plus one (+1.00) DS. DS means "diopters sphere". It indicates that the left eye’s correction has no astigmatism. Finally, the ADD number of +1.75 indicated the power that needs to be "added" to the distance prescription. It aims to give the patient a clear vision at a close range for reading and near point activities.

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