Pupillary Distance (PD)
Pupillary Distance (PD): What It Is and Why It Matters
What Is Pupillary Distance (PD)?
Pupillary Distance (PD) is the measurement (in millimeters) between the centers of your pupils. This measurement is essential for ensuring that your prescription lenses are aligned correctly in your glasses. Accurate PD ensures optimal vision clarity, reduces eye strain, and enhances comfort.
The average PD for women is 62mm, but this can vary from person to person.
Why Is PD Important?
Every pair of prescription glasses has an optical center, which is determined by your pupillary distance. If your PD is incorrect, your lenses may not align properly with your eyes, leading to:
✔ Blurry vision
✔ Eye strain and discomfort
✔ Headaches and difficulty focusing
✔ Distorted depth perception
Ensuring that your PD is measured accurately is key to getting the best results from your prescription glasses.
How to Find Your PD
Many eye doctors do not include Pupillary Distance (PD) in your prescription by default. If your PD is missing, you have a few options to obtain it:
✔ Contact your eye doctor – They may have it on file.
✔ Use an app – Apps like GlassesOn (available on the App Store and Google Play) can measure your PD and even determine your current prescription strength.
✔ Measure it yourself – You can use a mirror and a millimeter ruler to determine your PD at home.
How to Measure Your PD at Home
What You Need:
📏 A millimeter ruler
🪞 A mirror
Step-by-Step Guide:
1️⃣ Stand about 8 inches (20 cm) away from a mirror.
2️⃣ Hold a millimeter ruler against your forehead, just above your eyes.
3️⃣ Close your right eye and align the zero mark of the ruler with the center of your left pupil.
4️⃣ Close your left eye and open your right eye. Read the measurement where the center of your right pupil aligns with the ruler.
5️⃣ Repeat this process three to four times to ensure accuracy.
💡 Tip: If your PD varies slightly with each measurement, use the average.
Having a Friend Measure Your PD
If you have a friend to help, follow these steps:
✔ Keep both eyes open and have your friend align the zero mark on the ruler with the center of one pupil.
✔ Measure the distance from the center of one pupil to the center of the other.
✔ Have them sit or crouch slightly below you to stay out of your direct field of vision.
✔ Look at a distant object (10-20 feet away) instead of looking at the person measuring to keep your eyes still.
Single vs. Dual PD: What’s the Difference?
🔹 Single PD – This is a single number (e.g., 62mm) that represents the total distance between your pupils. It is used for most single-vision prescription glasses.
🔹 Dual PD (Monocular PD) – This consists of two numbers (e.g., 31/31mm) and measures the distance from each pupil to the bridge of your nose. It is typically used for bifocal, progressive, and multifocal glasses for a more precise fit.
Your optometrist may list PD as a single number or as a dual PD measurement, depending on your prescription type.
How to Calculate Near PD for Reading Glasses
If you are ordering reading glasses, your near PD (the PD needed for close-up tasks) will be slightly smaller than your distance PD.
How to adjust your PD for reading glasses:
✔ Subtract 3mm from your distance PD to determine your near PD.
✔ If using Dual PD, subtract 1.5mm from each eye’s measurement.
Example:
- If your distance PD is 63mm, your near PD would be 60mm.
- If your dual PD is 33/31mm, your near PD would be 31.5/29.5mm.
Final Thoughts
Pupillary Distance (PD) is a crucial measurement for getting the most out of your prescription glasses. Whether you're ordering progressive lenses, bifocals, or high-strength prescription glasses, ensuring that your PD is accurate will maximize comfort and visual clarity.
💡 Need help? Contact LadyBoss Customer Care, and we’ll guide you through the process to ensure your glasses fit perfectly!