How to Measure Your PD
PD measurement is used to make sure your lenses are optically centered, and it determines where you will look through the lenses of your glasses. It’s important that this measurement will be as accurate as possible for an optimal experience when buying glasses online.
PD, the abbreviation of Pupillary Distance, is the distance in millimeters between the centers of your two pupils. Having a correct PD on your glasses prescription ensures that you are looking through the ideal spot in your lenses.
Your prescription may show your PD. But if the PD is not available, how to get your PD?
1.The fastest and most accurate way is to ask your eye care professional if you have.
2.If not, ask your friend for help to figure it out, all you need is a ruler.
3.Or measure by yourself, all you need is a mirror and ruler.
Having a Friend Measure Your PD:
If a friend is measuring your PD, keep both eyes open and have your friend put the zero on the millimeter ruler over the center of one pupil, then measure the distance to the center of the other pupil.
Measuring Your Own PD:
Step 1: Stand 20 cm away from the mirror.
Step 2: With your face straight, hold the ruler against your brow.
Step 3: Close your right eye and align the ruler’s zero to the center of your left pupil.
Step 4: While looking straight, close your left eye and open your right eye.
Step 5: Read the mm line that lines up with the center of your right pupil. This number is your PD.
A ‘single’ pupillary distance number is the distance in millimeters between one eye’s pupil to the other eye’s pupil.
A ‘dual’ pupillary distance number is the distance in millimeters from each eye’s pupil to the center of your nose.
A single PD will be just one number, while a dual PD will have a number for each eye, marked ‘right’ and ‘left’. (Some prescriptions may have ‘OD’ for the ‘right’ eye, and ‘OS’ for ‘left’ eye.) And it is possible that right PD number is not the same with left one.
Pupillary distance will change when people are young as they are still physically growing. Once people reach maturity and stop growing, pupillary distance will change very little, if at all.
The PD number indicates exactly which part of the lens you look through. Therefore, the PD number is important for every type of prescription lens, including single vision glasses.
Your PD should be exact. If your lenses aren’t centered correctly, they can cause discomfort and eye strain. A small margin of error might not cause problems, but it’s better to be as accurate as possible.
You usually can’t find your PD number written on your eyeglasses. The numbers on the inside of the temple arms of some frames show the measurements for the frame itself.
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