Understanding Your
Glasses Prescription
OD, OS, Sphere, Cylinder... it's a secret language. Let's translate it into plain English.
Interactive Prescription Decoder
Enter sample numbers to see what they mean.
What This Means For Your Right Eye:
Sphere (-2.50)
The minus sign means you are nearsighted (myopic). Objects far away are blurry. A value of 2.50 is moderate myopia.
Cylinder (-0.75) & Axis (180)
You have astigmatism. Your cornea is shaped more like a football than a basketball, causing distortion. The axis (180°) tells the lab how to orient the lens to cancel this out.
Add Power (+1.50)
This indicates presbyopia. You need extra magnification (+1.50) for reading, usually in the form of bifocals or progressives.
The Vocabulary
- OD vs. OS
- Latin abbreviations. Oculus Dexter (Right Eye) and Oculus Sinister (Left Eye).
- Sphere (SPH)
- The main power of your lens. Measured in Diopters (D). (-) is for distance/nearsightedness, (+) is for farsightedness.
- Cylinder (CYL)
- The amount of lens power needed for astigmatism. If this is blank, you possess perfectly spherical eyes.
- Add
- Added magnifying power for reading. This almost always appears after age 40 due to presbyopia.
Can It Be Improved?
Your prescription measures the refractive error of your eye's optics (cornea + lens). While glasses correct the optics, they don't change how your brain processes the image.
Visionary works on the neural side. By improving your brain's processing speed and contrast sensitivity, you can often achieve better functional vision than your prescription alone suggests.