How To
Measure Your
Pupillary Distance
Here at Al-Aziz Optical we care about your eyes, after all you need them to see all the awesome things you do everyday. To ensure we get your prescription sitting perfectly in your lenses we need something called a Pupillary Distance Measurement (or PD for short). We know it’s a mouthful but keep reading and you will get your head around it in no time.
What is a Pupillary Distance Measurement?
Your PD is the distance between the center of your right and left pupils. We use this measurement to ensure that your prescription is sitting exactly where your eye needs it in your frames and not off to the side or below your line of sight. Your eyes should view the world through the best part of your lenses and since your pupils are in the middle of your eye, we make your lenses with that central point in mind. That’s why we can’t make up your unique prescription lenses until we have this measurement.
Why is a PD important?
Well apart from the fact that you might not have that 20/20 sight you are after if your PD isn’t right, it can cause eye strain, fatigue, or even double vision with higher prescriptions. All glasses are produced for optimal performance. We do this by fitting lenses to the frame so that the lens centers match your PD. Also, the higher your prescription, the bigger the effect an incorrect PD can have.
So now that you are a PD pro, let’s find out How to measure your PD! And don’t forget: if something doesn’t feel right, you can always contact us with your questions or for corrections and we will be more than happy to help you out.
How to measure your PD
What You’ll Need:
- A ruler with millimeter (mm) markings
- A mirror or a friend to assist
- A pen and paper to note down the measurement
Step-by-Step Guide
Step 1: Preparation
- Find a Well-Lit Area: Stand in a well-lit room where you have a clear view of yourself in the mirror.
- Gather Your Tools: Ensure you have a ruler with mm markings. If you’re using a friend to help, make sure they have a steady hand.
Step 2: Positioning
- Stand Close to the Mirror: Stand about 20 cm (8 inches) away from the mirror. If a friend is helping, sit or stand facing them at the same distance.
- Look Straight Ahead: Focus on a specific point straight ahead at your eye level to ensure your eyes are not shifting.
Step 3: Measuring
- Place the Ruler: Hold the ruler against your brow line, ensuring it is straight and aligned with your eyes.
- Align with the Center of Your Pupil: Start by aligning the zero (0) mark of the ruler with the center of your right pupil. Keep the ruler steady.
- Measure the Distance: Without moving the ruler, note the measurement at the center of your left pupil. This measurement in millimeters is your PD.
Step 4: Double-Check
- Repeat the Process: For accuracy, repeat the measurement a couple of times to ensure consistency. If a friend is helping, let them measure as well for a second opinion.
Step 5: Record Your PD
- Write It Down: Note down your PD measurement. If you have a different measurement for each eye (binocular PD), write down both values (e.g., Right PD: 32 mm, Left PD: 31 mm).
Tips for Accurate Measurement
- Stay Still: Avoid moving your head or eyes while measuring.
- Steady the Ruler: Ensure the ruler is held firmly against your brow.
- Use a Friend: If possible, have someone assist you to ensure a more accurate measurement.
Tips to keep in mind
Whilst the distance between your pupils is one length, you’ll have to halve it to work out the PD for each eye, e.g. if your PD is 60mm, your left and right eyes will be 30mm each.
If you can’t halve your PD to a round number, no problem – split them to the closest 0.5mm, e.g. if your PD is 60.5mm, fill in: right = 30mm, left = 30.5mm. We see this quite a bit so, don’t worry, we know how to deal with it.
- Average Adult PD: Typically ranges from 54 mm to 74 mm.
- Average Child PD: Typically ranges from 43 mm to 58 mm.
The average PD are shown above, If yours falls outside this, or you have a prescription over +/-6SPH, get in touch with us and we’ll give you a helping hand.