Convert eye prescription to 20/??

Question

I'm trying to figure out what my approximate visual acuity is (you know, the 20/__ thing). I know I probably can't come up with an exact number, but I'd like a ballpark figure because people are always asking! (My vision's pretty bad, so they're curious).

My glasses prescription is sphere -9.75 (right eye) and -8.00 (left), and my contacts are -8.50 and -7.50.

Can anyone help me? Thanks!

Answer 1

I agree that there is no formula to convert those numbers (especially with high prescriptions).  If you have had an eye exam recently, your doctor may have taken your uncorrected VA and you can call and ask.

My prescription is similar to yours (glasses: right -9.00 and left -9.50).  I had to find my VA for school and it came out to something like 20/2500.  That might give you a ballpark.

Answer 2

There is no formula but with your prescription you would not be able to see the "big E"  which is 20/400 so your vision is worse than 20/400