How to read glasses prescription?

How to Read Your Glasses Prescription？  

Your Simple Guide to Understanding Eyeglass Orders  

 

What Is a Glasses Prescription?  

A glasses prescription is a document from your eye doctor that tells the lab how to make your lenses. It includes numbers and abbreviations that describe your vision needs.  

 

You’ll need it when:  

• Buying glasses online  

• Replacing lost glasses  

• Getting a second opinion  

 

Key Terms Explained  

Abbreviation	Full Name	What It Means
OD	Oculus Dexter	Right Eye
OS	Oculus Sinister	Left Eye
OU	Oculus Uterque	Both Eyes (rarely used)
SPH	Sphere	Lens power for nearsightedness or farsightedness
CYL	Cylinder	Lens power for astigmatism (blurred vision)
AXIS	—	Direction of astigmatism (1° to 180°)
ADD	Addition	Extra magnifying power for reading (for presbyopia)
PD	Pupillary Distance	Distance between pupils (in mm)

Note: PD is usually written at the bottom (e.g., PD: 62 mm).  

 

Sample Prescription  

Eye	SPH	CYL	AXIS	ADD
OD	-2.50	-0.75	180	+1.75
OS	-2.25	-0.50	175	+1.75

 

How to Read This:  

• Right Eye (OD):  

  - Nearsighted: -2.50  

  - Astigmatism: -0.75 at axis 180°  

  - Needs reading help: +1.75 (bifocal/progressive)  

• Left Eye (OS):  

  - Slightly less nearsighted and less astigmatism  

• PD: 62 mm  

 

What the Signs Mean  

Sign	Meaning	Condition
- (minus)	Nearsightedness	Can't see far clearly
+ (plus)	Farsightedness or Reading Add	Can't see up close clearly

Note: If CYL and AXIS are blank → No astigmatism.  

 

Quick Tips  

• You have the legal right to get a copy of your prescription after an eye exam (U.S. FTC rule).  

• Always check PD — it’s required for accurate lens alignment.  

• For progressive or bifocal lenses, ADD is always present.  

• Keep a photo or printed copy of your prescription for future orders.  

 

Need to Order Glasses Online?  

Make sure you enter:  

✓ SPH (Sphere)  

✓ CYL (Cylinder) – if not zero  

✓ AXIS – if CYL is not zero  

✓ ADD – if you need reading help  

✓ PD – ask your optician if not on the form  

 

Pro Tip:  

Ask your eye doctor:  

“Can I please have a copy of my glasses prescription?”  

They must give it to you — even if you don’t buy glasses there!