The pupillary distance refers to the distance between the center of the pupils when the two eyes face the front and the line of sight is parallel. Generally expressed in English letters "PD", the unit is mm.
Classification of pupil distance
Binocular PD and monocular PD
Binocular PD: The distance between the center of the right eye pupil and the center of the left eye pupil. This type of measurement will be between 41-80 mm
Monocular PD: The distance from the center of the right (left) eye pupil to the midline of the nasal bridge (applies to monocular, squint, and gradient mirror fitting). This type of measurement will be between 20-40 mm
Far PD/Distance PD and Near PD
Far PD/Distance PD: The distance between the centers of the pupils of the two eyes when the eyes are looking into the infinity.
Near PD: The distance between the pupil centers when 30~40cm reading in front of eyes or working at close quarters.
Sometimes PD will be written as PD = 33/34.5, which means the distances between the nose and the center of the two pupils. In this case, PD = 33 + 34.5 = 67.5, so you can fill in 67 or 68. The only 1 mm or 2 mm will have no effect at all.
Sometimes there is Far PD/Distance PD or Near PD. If you are shortsighted, please fill in Far PD/Distance PD. If you need reader, please fill in Near PD.
- The average PD is 60-66 mm, and about 97% of people have a PD of 54-74 mm. So if you measure a PD value outside 54-74 mm, you may have made a measurement error.
- In most cases, the female standard pupil distance is 52-65 mm, and the male standard pupil distance is 58-71 mm.
- When the pupil distance is not integer (for example, 58.5), myopia please choose 59; hyperopia / presbyopia please choose 58.
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