Millions,
So I just went to the eye doctor and got a new prescription. It’s -4.5 on each eye. How can I convert that to 20/20 or, rather, 20/300? I tried googling, but I just don’t know the vocabulary to use.
No longer walking into trees,
birdmonster
To help with the vocabulary, visual acuity is what is measured as 20/20, 20/300, etc. The figure -4.5 is the refractive error, measured in diopters.
There is some correlation between visual acuity and refractive error, but but my understanding is that they really measure different things so there is no one-to-one conversion. You can find various tables on the Internet that purport to relate the figures, but I think they should be taken with a grain of salt. If you want to know your uncorrected visual acuity, ask your eye doctor or find yourself a Snellen chart and estimate it yourself.
bibliophage: Thanks. That was really helpful, plus, “diopters” is the second best word I’ve learned today. No one’s taking the gold medal from “foofaraw” though.