So, is your eyesight 20/20? Do you have visual acuity?
I have 20/20 eyesight, just had it checked last week. 
The eye charts used were developed in 1862?
Wow, I did not know that. That was a long time ago. One of the oldest professions. 
Yes.  It is. Visual acity is dependent also on the  sensitivity of the interpretive faculty of the brain.
How do they test for that?
Visual acuity
Visual acuity (VA) commonly refers to the clarity of vision. Visual acuity is dependent on optical and neural factors, i.e., (i) the sharpness of the retinal focus within the eye, (ii) the health and functioning of the retina, and (iii) the sensitivity of the interpretative faculty of the brain.
A common cause of low visual acuity is refractive error (ametropia), or errors in how the light is refracted in the eyeball. Causes of refractive errors include aberrations in
metres. If a person has a visual acuity of 6/12, he is said to see detail from away the same as a person with "normal" eyesight would see it from away.
Healthy young observers may have a binocular acuity superior to 6/6; the limit of acuity in the unaided human eye is around 6/3–6/2.4 (20/10–20/8), although 6/3 was the highest score recorded in a study of some US professional athletes. Some birds of prey, such as hawks, are believed to have an acuity of around 20/2;