Reading Your Prescription
Frequently Asked Questions: Understanding Your Eyewear Prescription
Table of Contents
Reading Your Prescription
How do I read my prescription?
Your prescription is divided under:
- OD (Oculus Dexter): right eye
- OS (Oculus Sinister): left eye
SPH (Sphere/Power):
- The first number indicates the correction for nearsightedness (minus sign) or farsightedness (plus sign).
- Notation: may show “PL” or “Plano” (=0.00—no correction needed).
- Common range: -10.00 to +6.00
Higher absolute values = stronger correction.
CYL (Cylinder) & Axis:
- For astigmatism, correcting irregular cornea curvature.
- Both values always appear together (have both or neither).
- Cylinder range: typically -4.00 to +4.00
- Axis: 1–180 degrees (shows direction of astigmatism).
- Note: Some doctors write "Cylinder" in the minus or plus form. We accept either.
Add (Addition):
- Extra magnification for reading (presbyopia, usually age 40+).
- Always positive (+0.75 to +3.00), requires bifocal/progressive lenses or two pairs.
- Higher Add value = stronger reading correction.
Prescription validity:
- Most are valid for 1–2 years. Always check the expiration date before ordering.
- If I don't have my prescription, can you get it from my doctor?
- Doctors aren't required to send prescriptions directly to us, but by law, they must give you a copy after your exam. Request it directly and take a clear photo for your records.
What does “Sphere” or “DS” in the Cylinder field mean?
- “DS” (Diopters Sphere): No cylinder/axis needed (no astigmatism). Write “None” in those fields when ordering.
What if my prescription has different abbreviations?
- OU (Oculus Uterque): Both eyes—same prescription.
- Balance (BAL): Non-prescription lens to match the other eye. Enter the same prescription.
- Prism & Base: Special correction for eye alignment (select this option if needed—we offer it!).
- NVO (Near Vision Only): Reading glasses only.
Pupil Distance (PD)
What is PD?
The distance in millimeters between the centers of your pupils—so lenses are perfectly centered for top comfort and vision.
Why does PD matter? Incorrect PD: can lead to eye strain, headaches, blurred vision, and trouble focusing (even with the right prescription).
How do I get my PD?
- Ask your doctor or optician (takes minutes and is often free).
- Measure at home: use our Online Pupil Distance Meter or a standard ruler & mirror.
- A friend can help ensure accuracy.
- Average PD: Adult: 54-74mm (Women: 62mm, Men: 64mm)
Which PD number(s) should I enter?
We simplify things for you—just enter your PD as it appears on your prescription. If you have separate right and left values, enter both. (For progressives, you’ll only enter your distance PD; our team will process accordingly.)
Common formats:
- Single number format (total PD): Example: 64mm.
- Right/Left separate (e.g., 31.5/32.5): Add numbers for total PD; e.g., 31.5 + 32.5 = 64mm.
- Single digit, repeated (e.g., 32/32): Means 32mm each eye; total 64mm.
For progressive lenses:
Just enter your distance PD (if your RX shows both near & far, just use the far/distance number). We take care of the rest.
Does PD change over time?
- It remains constant after full facial growth (ages 18–20). Children/teens need a new measurement with every prescription update.
Does PD affect frame size?
- No. PD centers your lenses—you can choose any frame, but for very narrow or very wide PDs, avoid frames that are extremely oversized or extremely small.
Lenses & Options
What lens prescriptions do you offer?
- Single Vision: One focus point (distance, reading, or computer).
- Bifocals: Distance (top) and reading (bottom) with visible line.
- Progressives (No-line Bifocals): Multiple zones with a smooth transition for the most natural vision.
Progressive lens options:
- Standard: Reliable, familiar design, budget-friendly.
- Premium: Advanced digital zone design for wider, smoother viewing—easier adaptation, especially for first-timers.
Lens Materials:
- Standard Plastic (CR-39): Best for low prescriptions, economical & clear.
- Polycarbonate: Impact-resistant, thin & light, ideal for kids, active use, rimless frames.
- High-Index (1.67, 1.74): Ultra-thin for strong prescriptions, reduces “bottle-bottom” look.
- Recommendation: Choose high-index if the prescription is over ±4.00.
What’s the difference between anti-glare (AR) upgrades?
- All AR coatings remove glare, improve appearance, and make cleaning easier.
How do I order Plano (non-prescription) lenses?
- Choose "Non-corrective Plano" at the start when entering RX.
- If you select “fashion” instead, lenses arrive branded with the frame’s name.
About tinting and sunglasses:
Tinting by Lens Material:
- Plastic (CR-39): Best for tinting. Accepts all tint depths from light to dark evenly and consistently. Recommended for prescriptions under ±4.00.
- Polycarbonate: Not recommended. Does not accept tint well. Light tints may be possible, but with limited, inconsistent results.
- 1.67 High-Index: Limited tinting. Accepts light to medium tints reasonably well, though not as evenly as plastic. Darker tints may be inconsistent. Best option for tinting with prescriptions ±4.00 and higher.
- 1.74 High-Index: Not recommended for tinting. Does not accept tint well; results are unpredictable. For very high prescriptions (typically ±6.00+) where thinness is the priority over tinting.
For higher prescriptions requiring darker tints: You have two options:
- Plastic (CR-39): Accepts dark tints evenly and consistently, but will result in thicker lenses for prescriptions ±4.00 and higher
- 1.67 High-Index: Keeps lenses thinner and lighter, but tint depth will be more limited and may be less consistent
Since sunglasses are typically worn only occasionally rather than all day, many customers with higher prescriptions choose plastic lenses for better sun protection, even if it means thicker lenses.
Keep in mind: the higher your prescription is above ±4.00, the more noticeable the thickness difference will be.
- Sunglass Frames: Tinting/polarization is extra (not included by default).
Options include:
- Solid tint: One color throughout. The most popular colors are gray, brown, and green, with blue, yellow, and pink also available.
- Gradient tint: Top dark, bottom light (great for driving). Available in the same colors as solid tint.
- Polarized: Cuts glare from water, snow, roads (perfect for outdoors) - Available in colors Grey, Brown, Greenish-Gray.
- Photochromic/Transitions: Darkens in sunlight, clear indoors
- Transitions Gen S: Fast, clear indoors, very dark outdoors. Available in colors grey, brown, and green.
- Transitions XTRActive: Even darker outdoors + tint indoors. Available in colors grey, brown
- XTRActive Polarized: All XTRActive benefits + glare-cutting polarization for the strongest sun. Available in grey color.
- Not sure? Polarized is best for outdoor life; photochromic offers daily versatility.
Can you customize rimless lens shapes?
Yes! We’ll resize or shape lenses to your specification or pattern.
(*Note: "Drill charge" may apply for rimless or custom lens requests.)
Warranties, Quality & Safety
Are lenses covered under warranty?
Yes. We cover:
Within 30 days of delivery (free):
- - Prescription accuracy issues - we'll remake your lenses at no charge
- - Manufacturing defects - scratches, coating problems, or other flaws
After 30 days (up to 1 year):
Contact us for a discounted replacement with the same prescription and specifications.
Is the frame still under warranty after lenses are installed?
Yes. Installing lenses doesn't void the manufacturer's frame warranty. If you need to make a warranty claim, the lenses must be removed before returning the frame. Contact us if you need assistance with lens removal and reinstallation.
Is buying glasses online safe?
Absolutely!
- Orders handled by licensed opticians (like local stores)
- All frames checked before/after lens installation
- We verify anything unclear in your RX
- Lenses made using professional technology
- Friendly customer support through every step
- Plus: bigger selection, better pricing, and shop-from-home convenience.
What if something’s not right?
- Give yourself 3–7 days to adapt to progressives.
- Most opticians will adjust frames for free, including for online purchases.
- If something feels wrong, contact us right away - don’t wait.
- If you update your prescription, keep your old frames handy.
- Pro tip: After you receive your glasses, stop in at a local store for a free fit adjustment.