1. Description of commonly used professional terms:

Abbreviations and full names Full name Description
R(Right)or  OD Right eye If the left and right eyes have different refractive powers, please pay attention to the distinction
L(Left)or  OS Left eye
S(Sphere) Ball mirror Myopia or hyperopia degree
C(Cylinder) Cylinder Degree of astigmatism
A(Axis) Axis Direction of astigmatism
VA(Vision) vision The clarity of the object
PD(R)、PD(L) monocular PD The distance from the center of the pupil of the left and right eyes to the center of the bridge of the nose
PD(R+L) Pupillary distance The distance between the pupil centers of the left and right eyes. Generally, the PD on the optometry sheet means the pupil distance of both eyes

How to read a prescription for an eye exam?
What do the terms “OD” and “OS” mean in ophthalmic examinations?
“OD” and “OS” are abbreviations of oculus dexter and oculus sinister, which are Latin words for the right and left eye. You may also see the abbreviation OU on prescription medications, which means “two eyes”. Some doctors and clinics may use the more modern terms “RE” and “LE”, which mean “right eye” and “left eye ”
How long is an eye exam prescription appropriate?
Eyeglass prescriptions usually expire after two years, although some cases require a shorter expiration time. Contact lenses usually expire after one year.

The video is linked below:


First we need to understand a few acronyms,OD(Oculus dexter) and OS (Oculus sinister),The OD is the latin abbreviation for right eye and the OS is the latin abbreviation for left eye.

The S or SPH is the Sphere, which tells us the strength of your prescription. This is usually indicated by positive or negative, negative for nearsightedness, positive for farsightedness. A positive number means you are long-sighted or hyperopic, and a negative number means you are short-sighted or myopic.

The C or C Y L is the Cylinder, it means the degree of astigmatism,the negative it means you have astigmatism in your eyes,For example, negative 1.0 means that your astigmatism is 100 degrees.

The Axis is the direction of the axis of astigmatism. For example, if the value of Axis is 140, it means that your astigmatism axis is 140, and the staff will adjust it according to this axis offset position during the glasses fitting.

The ADD is also a very important value, this is the doctor after the optometry to help you correct your eyes to the purpose of the degree .

What’s the PD? it is Pupillary Distance. How to measure pupillary distance? According to the measurement method in the chart, you can measure with a ruler, and you can accurately measure your PD at home alone, in front of a mirror.