It's a common question: you have a contact lens prescription handy, so can you use it to order glasses? No. The two prescriptions are written for different lenses in different places, and the numbers are often different.
Glasses sit farther from your eyes
Glasses sit about 12 mm in front of your eyes. Contacts sit right on the eye. That difference, called vertex distance, changes the power you need. For mild prescriptions the difference is tiny, but once powers get stronger (roughly beyond ±4.00), the contact lens power and glasses power can differ noticeably.
What's on each prescription
- Eyeglass prescription: SPH, CYL, Axis and sometimes ADD and prism for each eye. Sometimes PD.
- Contact lens prescription: power, plus measurements for fitting the lens to your eye, like base curve and diameter, and usually a specific brand of lens.
Contact prescriptions are also sometimes adjusted for comfort or for how a particular lens fits your eye, so they aren't a direct match for glasses.
How to get your eyeglass prescription
If you had an eye exam that included glasses, you're entitled to a copy of your eyeglass prescription. The FTC's Eyeglass Rule requires eye doctors to provide it after the exam at no extra charge. Call the office and ask them to send it.
If your exam was only for contacts, you'll need your eye doctor to write an eyeglass prescription, which may mean a quick refraction.
Ordering with your eyeglass prescription
Once you have it, you can type it in at checkout or upload a photo. Not sure what the numbers mean? Read how to read your eyeglass prescription, then pick a frame.
