Simply put, (because that’s how we like things) an eyeglass prescription is not the same as a contact lens prescription. Even though both are prescriptions to correct your vision, you actually can’t use them interchangeably.
So why do you need two different prescriptions? A couple reasons:
While contacts rest directly on your eyes, glasses rest several millimeters away (about 12 millimeters, to be exact). This difference in distance can translate to a difference in the strength of your prescription. If you used your glasses prescription for your contact lenses, the correction to your vision might not be strong enough, and if you used your contact lens prescription for your glasses, the correction might be too strong.
Contact lenses also needs to fit the size and shape of your eye where eyeglasses don’t, so the contact lens prescription includes additional elements, like base curve (the curvature of the lens), diameter (the width of the lens) and the name of the contact lens brand.
The easiest way to determine if you’re looking at an eyeglass prescription or a contact lens prescription is to look for a brand name. If there is one, you know it’s a contact lens prescription.
Have an eyeglass prescription but need a contact lens prescription? No worries—download our app and take our prescription renewal test. It takes just 5 minutes, costs only $20 and you’ll be issued a new Rx by a licensed doctor in 24 hours or less.
The Simple Contacts team is passionate about all things health. Follow along—we're just getting started.