Eyeglass prescription: How to read it?

Knowing how to understand many numbers and weird names is essential! When buying prescription glasses online, you will need only a few minutes of your time, your prescription and either a computer or a telephone.

 

We understand that knowing your prescription from (not just an eye) doctor can sometimes be quite a task. That's why we're here to teach you the basics.

WHAT DOES "OD" and "OS" MEAN?

OD stands for ‘oculus dextrus’, which is Latin for the right eye. OS stands for ‘oculus sinister’, which is for the left eye. But some doctors already have special forms for prescription, without abbreviations such as OD and OS. There is simply a Right and Left eye column or letters R and L.

WHAT DOES SPH MEAN?

SPH (or simply S) is an abbreviation for the sphere. A sphere is a number describing the "strength" of your lens. Right next to this number you will see a sign + (for farsightedness) or - (for nearsightedness). The larger number is, the more you need to correct your eyesight. 

We must not forget to mention, that if you have in your sphere sign =, this equals to sign -. 

COLUMNS FOR ASTIGMATISM

In a previous article, we explained in detail what astigmatism means.

 

Astigmatism often occurs in combination with hyperopia and myopia. If you have been diagnosed with astigmatism, then you will have filled in the columns called CYL and AXIS. If these boxes are blank then you do not suffer from the condition.

CYL (or ZYL) stands for cylinder. Cylinder is a special diopter for people suffering from astigmatism. It only works in one axis, or in one direction, in which the irregularity in your eye distorts your vision.

AXIS (or A, ACH) represents the orientation or angle of your astigmatism. It's from 1 to 180 degrees.  

WHAT ARE ADDITIONS (ADD)?

 

The ADD (or also the addition) is a figure that expresses how much stronger your reading glasses will be than distance glasses. If you find it in your prescription, you probably have presbyopia, or low vision, which occurs in people after the age of 40. The solution for you is either two glasses - one for distance and one for reading, or multifocal glasses that give you sharp vision at all distances.

If you are not sure if you have filled in the details correctly, feel free to contact our customer service centre. They will be happy to advise you and help you fill in your details.

WHAT DOES "PD" STAND FOR?

Your PD value is key to ordering eyeglasses online. PD (pupillary distance) it's a measurement in millimetres between your eyes from the centre of one pupil to the centre of the other. If your prescription does not contain this value, don’t worry. We have prepared a simple guide on how to measure your PD at home or you can try our online tool. When using our online tool, you will need a credit (or any other) card and camera (web or phone).

 

BUYING PRESCRIPTION GLASSES

We hope you've learned something new and that you can already read a glasses prescription like a (nearly) professional. Now you can kick off the season with new prescription glasses from Eyerim and share the knowledge with your friends.