How to Read Your Prescription & Order Glasses Online
Everything you need to know to order prescription glasses online with confidence.
The Numbers on Your Prescription
Your prescription (Rx) has four key numbers for each eye:
- SPH (Sphere) — Lens power. Negative (-) = nearsighted. Positive (+) = farsighted. Example: -2.00
- CYL (Cylinder) — Astigmatism correction. Blank or 0.00 if no astigmatism. Example: -0.75
- AXIS — Orientation of astigmatism correction (1-180 degrees). Only present if CYL has a value.
- PD (Pupillary Distance) — Distance between your pupils in mm. Critical for centering the lenses correctly. Often not printed on the Rx — ask your doctor.
How to Get Your PD
Your PD is essential for online ordering. You have three options:
- Ask your eye doctor — They must provide it. It's your medical data.
- Use Fytoo's online PD tool — Free, takes 2 minutes with a webcam.
- Measure with a ruler — Stand in front of a mirror, measure the distance between pupil centers in mm. Have a friend help for better accuracy.
Lens Types Explained
| Type | Best For | Price |
|---|---|---|
| Single Vision | One distance (near OR far) | Free with frames |
| Progressive | Near + intermediate + far in one lens | +$30-80 |
| Bifocal | Near + far with visible line | +$20-50 |
| Reading | Close-up work only | Free with frames |