Prescription Glasses Buying Guide
The Lucent guide
Look Sharp.
See Sharper.
Your next pair should feel like you. Start with the look you love, then get clear on your prescription, PD, frame fit, and lens options.
Your eyeglass prescriptionCurrent, complete, and easy to read.
Your pupillary distanceMeasured in millimeters for your intended use.
Your frame measurementsA comfortable pair is a useful starting point.
01 / The starting point
Understand your prescription.
Use a current eyeglass prescription, not a contact-lens prescription. Enter each value exactly as supplied, or use the prescription-upload option offered in the lens selector. Keep every plus or minus sign and the correct right- and left-eye labels.
- OD / OS
- OD means your right eye; OS means your left. Some prescriptions use R/L or RE/LE instead.
- SPH / Sphere
- The spherical lens power, in diopters. A plus or minus sign is part of the prescription, not an optional detail.
- CYL / Cylinder
- The lens power for astigmatism. Copy the value and sign when supplied; do not invent a missing value.
- AXIS
- The orientation of the astigmatism correction, in degrees. It describes direction, not lens strength.
- ADD / Addition
- Additional near power over the distance prescription. ADD alone is not a complete reading prescription; ask your prescriber to confirm what to enter for Near.
- Prism / Base
- Additional correction and its direction, when prescribed. Contact us about order suitability and ask your eye-care professional for measurements before proceeding.
Missing or unclear information? Do not guess, change signs, or substitute values to get through the form. Your prescriber can clarify the prescription; Lucent can help with the ordering steps.
02 / A small measurement that matters
How to get or measure your PD.
Pupillary distance (PD) measures the space between the centers of your pupils in millimeters. It helps position your lenses in front of your eyes. PD may not appear on the prescription from your eye exam. Measurement references
Start here / Professional measurement
Ask the practice that made your last pair.
Your previous optician may already have your PD on file. Check your prescription, patient portal, or previous glasses-order details for a clearly labeled measurement. When it is missing or unclear, request it from your optician or eye-care practice, or arrange a measurement appointment. Ask about any fee beforehand.
“Could you share my pupillary distance in millimeters, including the right- and left-eye measurements, and confirm whether it is for distance or near use?”
Tell the practice whether you are ordering distance glasses or a pair for reading or another specific working distance.
One number: single PD
63 mm
Also called binocular PD: the total pupil-to-pupil distance.
Example only. Do not use this number for your order.
Two numbers: dual PD
R 31 / L 32 mm
Also called monocular PD: a separate measurement from the center of the bridge of your nose to each pupil. The sides may differ.
Example only. Follow the labels, not an assumed order.
Two numbers do not always mean right and left. They can also be labeled Distance and Near. Confirm what your record means. Do not split a single PD in half to invent individual-eye measurements, and do not substitute distance PD for near PD or subtract a standard amount yourself.
At home: the ruler-and-mirror method
For a binocular PD estimate, use a physical millimeter ruler, a mirror, and good lighting. Professional measurement is the better choice when you cannot see the pupil centers clearly or your results are inconsistent.
- Set up. Face the mirror from about 8 inches (20 cm) away. Keep your head level.
- Position the ruler. Hold it horizontally against your brow, clear of your eyes.
- Align the starting point. Close your right eye. Line up the ruler’s 0 mm mark with the center of your left pupil.
- Switch eyes, not position. Keep your head and ruler still. Close your left eye and open your right.
- Read and repeat. Read the millimeter mark at the center of your right pupil. Repeat the full process three times. If the readings vary, ask an optician rather than choosing a number.
Method adapted from the VA’s PD measurement instructions (PDF). A home estimate is not a professional fitting and does not establish separate right/left or near PD measurements.
Use the right ruler.
Use millimeters, not inches. A printed ruler must be printed at 100% / actual size, not “fit to page.” Verify its scale against a physical ruler. A ruler displayed on a phone or computer screen may not be true to size.
Know when to ask for help.
For children, prism, strong or complex prescriptions, near-specific measurements, or uncertain results, arrange a professional measurement. Never use an online “average PD,” a frame’s size markings, or an unlabeled number.
03 / Make it feel as good as it looks
Find your fit. Then make it yours.
Look inside the arm of a pair you wear comfortably. You may see three size numbers, such as 52–18–140. Compare them with the measurements for your exact chosen frame and size.
Width of one lens
Space between the lenses
Length of the arm
Illustrative frame measurements only. These are not PD, and their sum is not the overall frame width.
A comfortable frame sits securely without pinching your temples, slipping down your nose, or resting heavily on your cheeks. Matching size numbers is a starting point, not a guarantee: shape, bridge design, and adjustments also affect fit. M and L are not universal sizes.
For style, choose the effect you enjoy: a bolder outline, a softer curve, a light metal frame, or a touch of color. Face-shape “rules” are optional; comfort and your own taste come first.
04 / Choose for the way you will wear them
Distance or Near? Start with your prescription.
Lucent currently offers single-vision prescription lenses, not progressive or bifocal packages. Single vision is designed for one prescribed viewing range. Choose the intended use your eye-care professional has prescribed, then review the options available for your frame.
Single vision / Distance
For seeing farther away.
Choose Distance when ordering the distance correction prescribed for you, such as a pair for viewing across a room or other far-away tasks.
Single vision / Near
For close-up tasks.
Choose Near for a prescribed reading or close-work pair. Confirm the complete near prescription and the PD for the intended working distance.
Buying glasses for a computer? A screen can sit farther away than a book. Ask your prescriber which viewing range you need rather than assuming a reading prescription is right for every screen. Do not calculate a new prescription from ADD yourself.
Compare the complete pair, not just a headline price.
Read your chosen frame’s price description to see what is included. Open Select Lenses to check the available packages, included features, and any upgrade charges. Review the frame, selected lenses, and total together in your cart; confirm shipping, tax, and any discount at checkout.
Package availability and suitability depend on the frame and prescription. Use our lens comparison guide, then confirm the current options in the selector. A more expensive package is not automatically the right choice.
05 / The final look
A moment to check the details.
- Frame: the right style, color, exact size, and quantity.
- Prescription: current eyeglass values, every sign, and the correct right/left eye.
- PD: measured in millimeters, with the single/dual format and distance/near use confirmed.
- Lenses: intended use, chosen package, and any upgrades attached to the correct frame.
- Checkout: complete price, discount eligibility, email, delivery address, shipping, and tax.
An error, an unexpected total, or a lens pairing that looks wrong is a reason to pause and contact Lucent, not to substitute a prescription or lens option.
A few details worth knowing.
My prescription does not show PD. Can I still get it?
Yes. Ask the optician or practice that made your previous glasses whether they have it recorded, or arrange a new measurement. PD may be recorded during dispensing rather than the eye exam. Confirm that the measurement matches the use of your new pair.
My PD or prescription does not match the form. What should I do?
Keep the original values and labels. Do not round, swap eyes, halve a number, or replace a value just to make it fit. Contact Lucent about entering the information; ask your prescriber to clarify anything that is clinically unclear.
Can a style preview confirm my size or PD?
No. A style preview is not a measurement or a professional fitting. Use actual frame dimensions and your own confirmed PD. Do not estimate either from a model photograph.
Your point of view. Your Lucent.
Find the pair that feels like you.
Explore the frames. Keep the essentials close. Ask us when you need a hand.
This guide provides general shopping and measurement information, not medical advice or a prescription. Your eye-care professional should confirm clinical values, intended use, and any specialist fitting needs.
Educational references
U.S. Department of Veterans Affairs: measuring PD (PDF); College of Optometrists of Ontario: PD and prescriptions; Versant Health: prescription terminology.
These sources provide educational background; they do not endorse Lucent Optical.
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