How can I tell how bad my vision is from my contact lens prescription?

Question

The prescription for my right eye says -5.5 and for my left it says -4.75. What does this even mean and where does this fit in with the whole 20/20 thing? I know my vision is pretty bad because without contacts or glasses I can barely recognize people from like 5+ feet away. I know to be legally blind it has to be 20/200 but how can I figure that out?

Answer 1

There isn't a way to tell you your visual acuity based on a contact lens prescription, it is a pretty high prescription, but not unheard of.

Answer 2

Use an eye chart or have the Dr. give you a visual acuity test.

Answer 3

there is no way to tell what your visual acuity is based on your contact lens prescription is. However, you prescription  is rather high, making you myopic, meaning that things you are looking at focus in front of the retina. Without your contacts in you are probably seeing at 20/100 or even worse.  Next time you see your optometrist have him/her tell you what your visual acuity is without correction, you will get a better idea talking it out with your doctor.

Answer 4

You are not legally blind whatever your Rx, and vision without glasses, if you get good vision with glasses or contacts.

You would be legally blind, if the vison you get without correction was the best you could get.

There isn't a direct connection between the power (-4.75 etc.) and the acuity (20/20 etc.) because it also depends on pupil size and some other factors.

A -5.00 Rx is going to be on the order of 20/300, unaided, but subject to a lot of individual variation.