Contact Lens vs Glasses Prescription: Why They Are Different
A contact lens sits on your eye; glasses sit about half an inch in front of it. That distance changes the power you need, so the prescriptions are not interchangeable.
Different power
For stronger prescriptions, the power of a contact lens and a glasses lens can differ noticeably because of the distance from the eye.
Different measurements
Contact lens prescriptions include base curve (BC), diameter (DIA) and a brand. Glasses prescriptions include PD and sometimes prism instead.
What to do
Ask your eye doctor for your glasses prescription. Most offices can give you a copy.
Frequently asked questions
Can I convert my contact prescription?
Not reliably at home. Ask your eye doctor for a glasses prescription.
Is my glasses PD on my contact prescription?
Usually not. You can measure it at home.
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.