If you wear glasses and want to go to wearing contact lenses instead, you may be wondering how to convert your glasses prescription into a contact lens prescription.
It, unfortunately, does not work quite that easily.
The difference between an eyeglass prescription and a contact lens prescription is how close the lens is to your eyes. Glasses are worn a few millimeters from your eyes (maybe 12-14mm) and contacts are, of course, worn right on your eyes. Because of this and how bent light travels before it enters the eye, there is a complicated formula that can be used to calculate an approximate contact lens prescription from a glasses prescription, but it doesn’t always work out to be correct. You wouldn’t want to solely use that calculation as it won’t be exact.
There are also other factors like the the radius of curvature and diameter of your cornea that need to be factored in as well. These measurements aren’t taken when you get a glasses prescription. If you have any astigmatism at all, that will also complicate things if you were to just use a formula or calculation.
Here’s a list of some online calculators for converting an eyeglasses prescription to contact lenses if you want to see what they’re like:
- Contact Lens calculator (swisslens.ch)
- Sphere Spectacle Calculator (coopervision.com)
- ToriTrack® Calculator (coopervision.com) – for toric lenses / astigmatism
- TRULIGN Toric IOL Calculator (bausch.com)
Get a Contact Lens Prescription
The best solution to get a contact lens prescription is to see an eye doctor/optometrist and get an eye exam that’s specifically for contact lenses. The doctor can give you a prescription for contact and a prescription for glasses. You can then have each made for you.
Your contact lens prescription will be good for one year. After that, you’ll need to go in for another exam and get another prescription written for you.
An eye exam will cost you about $80 or so. Going to a department store that has an Optical Department will get you in that range. Seeing a doctor who has their own office might cost you more. Check to see if you have vision insurance coverage, which may pay for part or even all of the exam and maybe your contact lenses and glasses.