How does pupillary distance

Eye doctors use this type of PD for distance vision glasses. Near PD is the distance between the pupils when an individual is looking at a near object, such as when reading. It is important to measure PD correctly. According to a study , PD can vary among individuals. The researchers note that various factors, including age, sex, and ethnicity, can influence the measurement.

For instance, research has shown that males typically have a higher PD than females, with various studies reporting an average PD of The researchers also state that this measurement can increase until a person is in their mids. After this age, PD tends to remain constant. Single or binocular PD measurement refers to the distance between the center of one pupil and the center of the other pupil.

A single PD measurement provides one number, such as 60, 63, or 55 mm. Dual PD measurements include two numbers. OD is short for oculus dexter, which refers to the right eye, and OS is short for oculus sinister, which refers to the left eye. Learn how to read an eye prescription here.

To use this method, people should stand about 8 inches away from a mirror. The resulting measurement is their single PD. Individuals can also measure their single PD with the help of another person. The individual who requires a measurement can look at an object that is about 20 feet away from them. To calculate a dual PD, people will need to measure from one pupil to the bridge of the nose, note the measurement, and then do the same for the other eye.

This process is not guaranteed to produce accurate results, so it is advisable to take several single and dual PD measurements and then find the averages. People who already wear eyeglasses can find their PD by putting their glasses on and asking another person to stand in front of them and mark two dots on the glasses right above the left and right pupils.

Then, they can measure the distance between the two dots. Pupillary distance PD. Reviewed by : Dr. Matthew Miller, OD on May 13th, Measure PD yourself 1. Print our downloadable PD ruler.

Place the ruler directly over the center of your right pupil so that the ruler is horizontal. Place against forehead for added stability.

Stand in front of a mirror, or ask someone else to measure for you. For greatest comfort and clarity, the optical center of each lens of your glasses should be aligned directly in front of the center of your pupil. PD is measured in millimeters mm. Pupillary distance can vary widely — roughly between 51 mm and Monocular PD. This is the distance between the center of your pupil and the middle of the bridge of your nose. Monocular PDs are required for accurate fitting of progressive lenses.

Binocular PD. This is the distance between the center of the pupil of one eye and the center of the pupil of the other eye. Due to facial asymmetry, monocular PDs aren't always exactly the same. But the sum of your two monocular PD measurements should always equal your binocular pupillary distance. Pupillary distance measurements usually are taken when you are being fitted for glasses after your eye exam.

An optician typically will measure your PDs with a high-precision measuring device called a pupillometer.