Your eye prescription may look like a jumble of letters and numbers, but each element plays a key role in helping you see clearly.
Here’s your no-nonsense guide to understanding it – point by point.
O.D. and O.S.
You’ll often see O.D. and O.S. on your prescription.
These are Latin terms: oculus dexter (right eye) and oculus sinister (left eye). O.U. stands for oculus uterque, meaning both eyes.
These abbreviations help your eye doctor note measurements for each eye individually.
Minus or plus?
A minus (-) sign next to a number means you’re nearsighted and have difficulty seeing objects at a distance.
A plus (+) sign or no sign indicates farsightedness, meaning you struggle to see close-up.
The higher the number, the stronger your corrective lens needs to be.
CYL and AXIS
CYL (cylindrical correction) shows if you have astigmatism – a common condition that distorts vision. If there’s a number under CYL, it means your eye isn’t perfectly round.
AXIS describes the angle (0 to 180 degrees) at which this imperfection occurs and needs correcting.
DV and NV
DV stands for distance vision – the correction you need to see things far away. NV stands for near vision, used to improve reading or up-close focus.
If you have both, you may need bifocals or multifocal lenses to help in both situations.
ADD
ADD refers to the extra magnifying power needed in the lower part of bifocal or multifocal lenses to help with reading.
In contact lenses, this is sometimes labeled as low, medium, or high rather than a specific number.
Glasses versus contacts
Your glasses prescription won’t work for contact lenses. Glasses sit about 12 mm from your eyes, while contacts rest directly on the eye.
Contact prescriptions also include fit-specific details like lens curvature, diameter, and sometimes lens brand or material.
Base curve and diameter
Contact lenses have two key measurements: base curve and diameter.
The base curve (usually between 8 and 10) must match the natural curvature of your eye.
The diameter (typically between 13 and 15 mm) ensures the lens covers your eye correctly.
What does 20/20 vision really mean?
20/20 vision simply means you have average visual sharpness at 20 feet. It’s not “perfect” vision – someone with 20/15 can see even better.
The higher the second number (e.g. 20/100), the blurrier your distance vision. Glasses or contacts can often correct it, but not always.
Will your vision get worse with age?
Your actual sight may not worsen, but the risk of age-related eye conditions increases.
After age 50, your chances go up for issues like macular degeneration, cataracts, glaucoma, and diabetic retinopathy.
Wearing sunglasses, eating healthy, and protecting your eyes can help.
How often should you get an eye exam?
Even if you don’t notice changes, your prescription can shift. Adults with vision issues should get checked every 2 years, and annually after 40.
If you have no vision problems, every 5 years is fine until age 30, then every 2–4 years until 65, and every 2 years after that.
Article based on information from Healthline.com.