How to Read your Eyeglass Prescription?
                     Understanding Your Eyeglass 
Prescription
Introduction
Do you want to maintain good eyesight? In that case, you have to go for eye exams 
at regular intervals. This vital step will keep your eyes healthy and retain the 
sharpness of your vision. During an eye exam, an optometrist or ophthalmologist 
will closely look for any early signs of eye disease. 
It is tough to understand eye prescriptions. They are generally a blending of letters 
and numbers. You may be in a state of confusion when you are not aware of its 
meaning. Let us understand how to read eyeglass prescription.
What the Numbers Represent?
You glance at your prescription for glasses, you will encounter a couple of 
numbers, such as OS and OD. OS stands for oculus sinister that is left eye. OD 
stands for oculus dextrus, which is the right eye. On certain occasions, you will get 
to see OU, which is a situation involving both eyes. 
Unit Measurement
If your eyesight needs correction, you will get a prescription for glasses or lenses. 
The prescriptions will differ from individual to individual when issues vary. These 
numbers refer to dioptres. This is the unit of measurement of lens power. In short 
form, the diopter is referred to as "D."
How to Read Eyeglass Prescription?
Generally speaking, the more the deviation of the number on the prescription, the 
worse is your eyesight condition. A “plus” (+) notation symbol in front of the 
number indicates you are farsighted. A “minus” (-) notation symbol means you 
are nearsighted. 
For instance, -1.00 on your prescription means you have one diopter of near-
sightedness. This is on the mild side. On the other hand, -4.25 on your prescription 
mean 4 and 0.25 diopters of near-sightedness. Compared to the first case in the 
second one, you will require more powerful lenses. On the same lines of thought, 
+1.00 indicates a small amount of farsightedness, when compared to +5. 
Reading the Prescription of 
Astigmatism
Some people have a cornea condition called astigmatism. This is a condition that 
refers to imperfections in eye curvature. In such circumstances, an individual will 
have blurry vision at all times. People suffering from this condition will have three 
numbers on the prescription. They are written in S x C x Axis format. The cornea is 
in the shape of a football instead of a basketball.
The S is a reference to the "spherical" portion. It indicates the magnitude of near-
sightedness or farsightedness, as discussed in the above paragraphs. The C is a 
reference to the "cylinder" and can be either a negative or a positive number. It 
indicates the extent of astigmatism that you are suffering from, and the unit of 
measurement is diopters. The bigger this number, the higher astigmatism has 
impacted you. 
The Axis shows the astigmatism orientation. The number may be between 0 to 180 
degrees. Stating the extent of astigmatism you are suffering from is not adequate. 
It is also helpful to gather information about the point where curvature difference 
happens. 
Two instances of the way prescriptions with astigmatism would appear:
-3.00 +2.50 x 90
+2.50 +1.00 x 135
The first prescription indicates that the individual has 3 diopters of near-
sightedness with 2.5 diopters of astigmatism and an axis of 90 degrees. The second 
prescription refers that the individual having 2.5 diopters of farsightedness, 1 
diopters of astigmatism, and an axis of 135 degrees.
Conclusion
Your prescription may have notes from your Lasik surgery specialists. The lenses 
may be anti-reflective, progressive, or photochromic. Some of them may have a 
coating on them that makes them scratch-resistant. If the Latin abbreviations and 
mathematical numbers bother you, talk to your healthcare provider to clarify 
issues.
 
A wise approach is to have your eyes examined at least once a year. This step is 
crucial if you want to maintain your eye health.