Pupillary Distance: Why Its Accuracy Matters

Your optometrist will perform tests and measurements to determine the ideal eyewear for your needs. While pupillary distance (PD) does not appear on your prescription, it matters when getting glasses. PD refers to the measurement of the distance between your pupils. 

Keep reading to learn more about PD and why it matters. 

What Is Pupillary Distance?

Also called interpupillary distance, PD measures the distance between your pupils. This part of the eye widens to allow light and narrows to focus on a nearby object. Your pupils help you see when it’s too bright or dark. Moreover, PD is essential when getting new prescription eyeglasses. Your optician might use a digital PD meter, pupillometer, or a special ruler to measure your pupillary distance. 

Besides sizing, eye care providers use PD to assess areas of your vision or eye function. However, it isn’t usually vital to your vision treatment management. That’s why you don’t see it on your prescription but still need PD when getting new glasses. 

Why Is It Important?

The center part of your prescription is the clearest. You will feel more comfortable wearing your glasses if the center of your lens is in front of your pupil. It will also help you see clearly and reduce the likelihood of eye strain. Keep in mind that PD might change depending on the type of glasses.

PD helps eye doctors further assess stereo acuity or depth perception. It helps them distinguish the difference between your left and right eyes’ field of vision. Your doctor might also refer to your PD when testing near-point convergence, which happens when your eyes focus on a nearby object. Pupillary distance tends to shorten as the eye converges, and your doctor will observe changes in your PD.

Are you experiencing changes in your vision? Schedule a visit with your local eye doctor at Vienna Eyecare Center to determine if you need new eyeglasses or contact lenses. Call us at (703) 938-7633, or fill out our contact form to make an appointment.