Finding the right pair of frames and the perfect prescription can be challenging. Of course, you’ll need to factor in your budget, the size and shape of the frame you’re interested in, and what coatings you’ll choose. You’ll also need to consider your pupillary distance.

If you’ve only purchased glasses in a store, you may not even be aware this important measurement exists. Now that it’s possible to order glasses online, you may come across order forms that require a pupillary distance be included.

What is pupillary distance?

female optician measuring woman's pupillary distance

Pupillary distance is the measurement from the center of one pupil to the center of the other pupil. It’s always measured in millimeters, and you may see it referred to as PD. No fancy equipment is needed to determine your pupillary distance, and it can be done in your own home if you have a little help.

How pupillary distance impacts your prescription lenses

The pupillary distance is used to customize your prescription glasses to your exact needs. Depending on your prescription, the PD can help place the lens in your new frames where it will be most helpful to you. A more custom fit prevents eye fatigue and strain while making your glasses more effective. It’s also useful for contact lens wearers.

In some areas of the world, pupillary distance is considered a dispensing tool, and it’s not included as part of the prescription. For more sophisticated corrections, you may need more detailed measurements. A qualified practitioner can help answer any questions or concerns you might have.

How to measure your pupillary distance

If you’re having your annual eye exam, your doctor can easily determine your PD then. Should you need your PD at another time, and you don’t have access to your records, there are mobile and web apps that can determine the measurement.

Low-tech options are available. Though it’s easiest to have a second person available to help you determine your PD, you can do it alone if you have to.

Start by standing 8 inches from a mirror. Place a ruler against your forehead and close one eye. Carefully line up the edge of your ruler so the 0 mm mark is at the center of your pupil in your still-open eye.

Focusing straight ahead, close your eyes for a moment. Leave the eye you’ve marked at 0 mm closed and open your other eye. Determine which millimeter mark lines up with the center of that pupil, and you have your pupillary distance.

Aren’t sure you have the right measurement? The average PD for an adult falls between 54 and 74 mm. For children, you can expect to have a PD between 43 and 58 mm.

Ordering your new glasses

Whether you’re ready to place your new order or you still have some questions about pupillary distance, Main Fashion Optical in Bergenfield and Passaic, NJ, is available to help you. Call today to set up an appointment with our qualified staff, or walk in and you’ll be on your way to a brand new pair of eyeglasses.