How to read an eyeglass prescription

How to read an eyeglass prescription

What do all these letters and numbers mean?




If you have questions about reading and filling out prescriptions, the following pictures can help you understand the process. This is what you might see. The form usually includes terms such as OD, OS, SPH, CYL, etc., which are printed digitally or handwritten by a doctor or optometrist.

RX SPH CYL AXIS PD
OD -4.50 -1.25 100 68
OS -3.50 -1.75 125 68

-OS VS OD-
OS: Oculus sinister, meaning left eye; can also be represented by “L”.
OD: Oculus dexter, meaning right eye; can also be represented by “R”.

-SPH-
SPH is short for the sphere. It shows your degree of myopia/hyperopia, in other words, nearsightedness/farsightedness.
A negative number here indicates myopia, therefore, -5.50D means 300 degrees of myopia.
A positive number here indicates hyperopia, therefore, + 2.50D means 250 degrees hyperopia.

-CYL-
is short for the cylinder. It indicates your level of astigmatism, a condition where the cornea is irregularly shaped and causes blurred vision.

-AXIS-
the axis describes the direction of astigmatism.
-1.00 means 100 degrees of astigmatism.
100 means that the astigmatism direction is 100 degrees.

- PD -
Interpupillary distance (PD) or interpupillary distance (IPD), is the distance between the centres of the pupils when the eyes are looking straight. It is in millimetres.
The average PD for adults is between 54 mm and 74 mm, and for children is between 43 mm and 58 mm.


PD refers to the pupillary distance or the distance between your pupils.