An eyeglass prescription is written in a standardized format with standardized notation so it can be interpreted worldwide. Let’s look at one and break it down:
The letters OD and OS in front of a prescription let us know which eye each string of numbers is for. OD (Oculus Dexter) stands for right eye and OS (Oculus Sinister) for left eye.
-1.50 -0.50 x 010. The first number (-1.50) tells us the spherical refractive error (Sphere), for farsightedness or nearsightedness. In this case, because there is a minus sign in front of the 1.50, this patient is nearsighted. A plus sign would indicate farsightedness.
The second number (-0.50) is the astigmatism (Cylinder). If there is no astigmatism, we generally write the letters DS or SPH after the first number to let the optician know that we didn’t just forget to write in the astigmatism.
The final number (010) is the direction (Axis) of the astigmatism. Astigmatism, a football-shaped eye, can be measured in any direction around the clock. We use the numbers from 0 to 180 to indicate the orientation of the football shape.
At last, the Pupillary Distance (PD), which is the distance between the pupils in millimeters. This measurement is needed when prescription lenses are being mounted in your eyeglass frames. If the PD is not included in your prescription, please read more here.
Prism and Addition are for specific uses like prism correction or bifocal or progressive eyeglasses. We do not make such categories of eyeglasses. If your prescription has values in the PRISM or ADD fields, we strongly encourage to consult a local optician.
For any information you may need about your prescription, do not hesitate to contact our Help Desk.
<< I'm ready to enter my prescription details now.
Pupillary Distance Measurement (PD)
Pupillary Distance (PD) is the distance between the pupils in millimeters. This measurement is needed when prescription lenses are being mounted in your eyeglass frames.
In general, PD measurements fall in the range of 48mm to 73mm. The most common measurements are between 58mm and 68mm.
You can use one of three methods to obtain this measurement:
Method #1 (recommended):
The simplest method is to go to your Eye Doctor or Optometrist for an eye exam. Ask your Eye Doctor or Optometrist for your PD measurement.
Method #2:
You can use this method wearing glasses, contacts, or no visual aids. You will need: a mirror you can stand in front of, a ruler with millimeter measurements.
Follow the steps below:
1. Stand with you face about 20 cm (8 inches) from the mirror.
2. Close your right eye and look only with your left eye.
3. Place a ruler flat against the mirror and align it horizontally with the millimeter scale pointing up.
4. Look over the top of the ruler and align the zero mark in the center of your left pupil.
5. Open your right eye and close the left, but do not move your face or the ruler.
6. Read the millimeter measurement corresponding to the center of your right pupil.
7. Repeat the procedure several times to make sure you have a consistent measurement.
Method #3:
You can use this method only if you are wearing glasses. You will need: your glasses, a NON-permanent marker, a person to help you, a ruler with millimeter measurements.
Follow the steps below:
1. Have your helper stand in front of you and mark a dot in the center of each pupil on your glasses.
2. Measure the distance between the dots in millimeters.
For any information you may need about your prescription, do not hesitate to contact our Help Desk.
<< I'm ready to enter my prescription details now.
