What is PD in Eye Prescription?
A Simple Guide to Pupillary Distance
When you see "PD" on your prescription, you might wonder: "What exactly is PD?" This seemingly small measurement is incredibly important—it directly affects the comfort and visual clarity of your glasses.
What is Pupillary Distance (PD)?
Understanding This Critical Measurement
PD refers to pupillary distance—the specific distance (in millimeters) between the centers of your pupils. This essential measurement ensures the optical centers of your lenses align perfectly with your pupils.
Measured in Millimeters
Typically between 54-78mm for adults
Alignment Critical
Ensures lens centers match pupil positions
Essential Information
Required for all prescription eyewear
MOXBOS Insight: An inaccurate PD measurement can cause eye strain, headaches, and blurred vision—even with a perfect lens prescription.
Why PD is Essential for Clear Vision
The Impact of Accurate PD Measurement
Though it might seem like a minor detail, PD is extremely important for vision correction and overall visual comfort.
Prevents Blurry Vision
Ensures optical centers align with pupils
Reduces Eye Strain
Eliminates discomfort from misaligned lenses
Critical for Progressives
Essential for proper alignment of multifocal zones
Special Note: For progressive lenses, PD accuracy is even more critical as it determines the alignment of different prescription zones that provide a seamless visual experience.
Understanding PD Types
Single PD
The total distance between the centers of both pupils. This is a single number measurement (e.g., 63mm).
Best for: Single-vision lenses
Dual PD
Measures the distance from your nose bridge to each pupil separately (e.g., 31mm/32mm).
Best for: Progressive and bifocal lenses
MOXBOS Recommendation: If you're getting progressive lenses, always request dual PD measurement for optimal visual clarity. Our opticians always measure both values for multifocal prescriptions.
How to Measure Your PD
Simple Methods for Accurate Measurement
Measuring your PD is easier than you might think. Here are reliable methods you can use at home:
Position Yourself
Stand about 8 inches (20 cm) away from a mirror. Hold a ruler against your brow line.
Align Left Pupil
Close your right eye. Align the ruler's zero mark (0mm) with the center of your left pupil.
Measure Right Pupil
Keep the ruler steady. Close your left eye and note the measurement at your right pupil center.
Pro Tips:
- Average PD is 54-78mm - measure 2-3 times for accuracy
- Use our MOXBOS PD measurement app for digital precision
- Have a friend assist for more reliable results
What If Your Prescription Lacks PD?
Solutions for Missing PD Values
Sometimes optometrists omit PD from prescriptions. Here's what to do if yours is missing:
Contact Your Eye Doctor
They have your measurement on file and can provide it quickly.
Measure It Yourself
Follow our step-by-step guide for reliable at-home measurement.
Check Previous Glasses
Your old prescription or glasses may contain your PD measurement.
MOXBOS Service: Visit any MOXBOS store for complimentary PD measurement—no appointment needed! Our experts use precision instruments for perfect accuracy.
Your Vision Comfort Matters
Though PD might seem like a minor detail, it's crucial for visual comfort and clarity. Whether you're getting prescription glasses, sunglasses, or progressives, accurate PD measurement ensures comfortable, clear vision.
At MOXBOS, we prioritize precision in every measurement. Our digital PD tools and expert opticians ensure your glasses fit perfectly and perform optimally.