Question 1

What is pupillary distance (PD)?

Accepted Answer

Pupillary distance (PD) is the distance between the centers of your pupils, measured in millimeters. It's a crucial measurement for eyeglass fitting as it ensures your lenses are properly centered over your eyes for optimal vision and comfort.

Question 2

How do I measure my pupillary distance?

Accepted Answer

You can measure PD using a ruler and mirror: 1) Stand 8 inches from a mirror, 2) Hold a ruler against your forehead, 3) Close one eye and align the ruler's zero mark with the center of your open pupil, 4) Switch eyes and note where the center of the other pupil aligns, 5) The distance between these points is your PD.

Question 3

What's the difference between distance and near PD?

Accepted Answer

Distance PD is measured while looking at objects far away (used for distance vision lenses). Near PD is typically 3mm smaller and used for reading glasses or bifocal/progressive lenses. The difference accounts for how your eyes converge when focusing on close objects.

Question 4

Why is accurate PD measurement important?

Accepted Answer

Accurate PD measurement ensures your eyeglass lenses are properly centered over your pupils. Incorrect PD can cause eye strain, headaches, distorted vision, and discomfort. For progressive lenses, precise PD is especially critical for optimal performance.

Question 5

Can I use the same PD for all frame types?

Accepted Answer

While your PD measurement remains constant, different frame types may require adjustments. Progressive lenses need more precise measurements, while single vision lenses are more forgiving. Frame size and bridge width can also affect how the PD is applied.

Question 6

What if my PD measurements are different for each eye?

Accepted Answer

It's normal to have slightly different PD measurements for each eye. This is called PD asymmetry. If the difference is more than 2mm, it's important to use individual eye measurements rather than a total PD to ensure proper lens centering for each eye.

Pupillary Distance Calculator

Key Benefits:

Prepare for Measurement

Position the Ruler

Measure Each Eye

Calculate Total PD

Scenario:

Related Calculators

Frequently Asked Questions