How to Measure Your Pupillary Distance (PD)?

Your pupillary distance (PD) is the distance between the centers of your pupils. Your PD is an important part of your prescription because it shows exactly which part of the lens you look through. This measurement is used when preparing to make prescription eyeglasses, it is different from person to person and also depends on whether they are looking at near objects or far away.

Every set of the prescription lens has an “optical center,” which is determined by pupillary distance. Pupillary distance is used to determine where you look through the lens of your glasses and should be as accurate as possible. A pupillary distance measurement is necessary for properly fitting your eyeglass lenses. There is no reason to walk around with inaccurate glasses when it is so easy to get this number.

Your PD number will be in the "PD" or "pupil distance" section of your eyeglasses prescription. This is usually separated from the "grid" part of your prescription, in which the doctor writes out the main prescription information.

It is best to measure the pupil distance accurately. If there is an error, it will make your eyeglasses tired or cause discomfort and eye strain. Therefore, the measurement of pupil distance should be as accurate as possible.

Because each person has a different face shape, the specific pupil distance varies from person to person. Statistically, the average pupil distance for adults ranges from 57 mm (2.25 inches) to 72 mm (2.83 inches). The average PD for women is between 55 mm and 70 mm, and the average pupil distance for men is between 60 mm and 75 mm.

Incorrect over-pupil distance can lead to dizziness, headache, and blurred vision. Your vision is centered on a small section of the lenses, so a PD number is needed to shape the lenses to perfectly suit your needs.

A person's pupil distance changes when he is young because the body is developing. Once it stops growing, the pupil distance will be fixed and will not change.

Usually, the pupil distance does NOT appear on your eyeglasses. The numbers on the inside of the temple arms of some frames are the size of the frame itself. Your PD number should be written on your eyeglass prescription in the PD section.

A 'single' pupil distance is the distance between the pupils of two eyes. A 'dual' pupil distance is the distance from the pupil of each eye 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 the 'left' eye.)

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 pupil distance will not affect the size of the eyeglasses frame, it will affect the shape of your lenses.