How important is pupillary distance when ordering glasses?

[Allardt]

When i order eyeglasses online, their customer services ask me the pupillary distance. She said it is very important to buy prescription eyeglasses. Can you tell me Why? What's the function of pupillary distance for buying eyeglasses?

[Alleene]

Pupillary Distance, it is the distance between two pupils when two eyes face parallelly. Measuring pupillary distance is in order to make the distance of lenses optical center and the distance between the pupils eyes consistent , making the user comfortable. Otherwise, it may not make proper eyeglasses for your, and users will appear fatigue, dizziness, nausea.