My eyeglass prescription

Have you decided to get new prescription glasses? Great idea! The most important thing for ordering new glasses is the EYEGLASS PRESCRIPTION. To obtain one, you must go to a vision specialist who will perform a vision screening and write a prescription for glasses that suit you and your eyesight the most. However, prescriptions for each optics or eye clinic differ by their appearance and sometimes also by abbreviations or ways of noting their terms, so, unless you are an optician or a "skilled" eyeglass user, reading and understanding a prescription might be daunting at first.  This is where we come in to help and decipher what is written in the prescription.

1)      OD and OS – sometimes eye doctors use Latin names to describe the left and right eye – oculus dexter (OD or right eye) and oculus sinister (OS or left eye). Therefore, if these abbreviations are used in your glasses prescription, you will find all information about your right eye at OD and everything about your left eye at OS.  

2)      SPH/sphere – these numbers indicate how powerful your glasses will be or, to be more precise, how spherical is your optical lens. Commonly, these are called the pluses and minuses. Lens power is measured in dioptres (indicated with a D), and glasses are prescribed in powers increasing by 0.25D large degrees. Sometimes, instead of numbers this field has the letters pl (or planum) – this means that the spherical power is zero and you must indicate it as 0.00 when ordering glasses online.

3)      CYL/cylinder and AXIS – if you have astigmatism (to find out more, click here), your prescription will also have numbers in the columns next to cyl (cylinder) and axis, these numbers indicate how much added lens power is required and at which degrees the cylinder power must be located. 

Different doctors can indicate the same cylinder correction in two ways: by using the plus or minus cylinder form. So don’t worry if your prescription suddenly has vastly different numbers and the cylinder has turned from a minus into a plus, this does not mean that one of the doctors has made a mistake or your eyesight has significantly changed all of a sudden, it just might be that different ways of writing it are used, both of which are correct!

4)     ADD or added magnifying power – if a number is written in this field, it means that you will need glasses of varying power, or glasses with progressive or anti-fatigue lenses when looking far and near (you can read more about these optical lenses here). Some eye doctors write prescriptions without indicating the added magnifying power, but each eye has two fields, upper and lower. The upper field indicates that this power is required for far-sighted glasses, whereas the lower field is the power for near-sighted glasses. The difference between far and near power also constitutes the added magnifying power. However, if the ADD field has been filled in your prescription or if you have a prescription with lower and upper fields filled out, don’t hesitate to write to us or ask our optics consultants and we will help you find out which type of optical lenses suits you the best!

5)      Pupillary distance (also indicated as PD or DPP) – these numbers indicate the distance between the centre of both pupils, and knowing this distance is essential for creating precise eyeglasses.  If the distance from one pupil to the middle of the nose bridge matches the other pupil’s distance to the middle of the nose bridge, the distance is indicated by one number, for instance, 62mm. However, slight asymmetry is frequently observed, so the total distance might be written in the prescription with numbers in brackets indicating each eye’s distance, for instance, 62mm (30/32) or immediately indicating that for the right eye it is 30mm and 32mm for the left eye. If your prescription only indicates the total distance, then you need to divide this number by 2 when ordering eyeglasses.

It is also important to know that the pupillary distance can differ when ordering glasses for near or far, usually, the distance will be a few millimetres smaller in close distances. Therefore, it is possible that separate numbers are indicated in the prescription, for instance, 62mm for far objects, and 58mm for close objects.  If you're ordering reading glasses, you have to select pupillary distance for close objects.

The prescription will also indicate what the glasses are prescribed for: far distances, work (reading and working at close distances) or continuous wear. Eye doctors also recommend optical lenses in prescriptions.