What Does ADD Mean on an Eyeglass Prescription?
ADD (addition) is the extra magnifying power you need to see up close. If your prescription has an ADD value, you probably need bifocals, progressives or reading glasses.
Why ADD appears
After about 40, the eye's lens loses flexibility and focusing up close gets harder. This is called presbyopia and it is completely normal.
Typical values
ADD goes from +0.75 to about +3.00 and usually increases slowly with age. It is often the same for both eyes.
Which lenses use ADD
Bifocals (two zones with a line), progressives (gradual, no line) and single-vision reading glasses all use it.
Frequently asked questions
Do I have to use ADD?
Only if you want lenses that also help you read. For distance-only glasses, the ADD is not used.
Can I just buy readers?
Off-the-shelf readers only work if both eyes have the same power and no astigmatism.
Related guides
This guide is for information only and does not replace an eye exam. If you have eye pain, sudden vision loss or flashes of light, see a doctor right away.