I got my eyes zapped just over a week ago and the doc said at my 1 week checkup that my vision is now 20/12. So what does that mean, am I now half blind or what?
I would appear not. According to this site the use of the term "20/20" refers to this complex calculation created by some Dutch dood called Snellen (1834-1908)
Someone with 20/20 (visual acuity) is just able to decipher a letter that subtends a visual angle of 5 minutes of arc (written 5') at the eye. (5' of arc is 5/60 of a degree, because there are 60' of arc in 1 degree.) What this means is that if you draw a line from the top of a 20/20 letter to the eye and another line from the bottom of the letter to the eye, the size of the angle at the intersection of these two lines at the eye is 5' of arc. (Also, the individual parts of the letter subtend a visual angle of 1' of arc at the eye.) It does not matter how far away something is from the eye; if it subtends an angle of 5' of arc at the eye, then a person with 20/20 visual acuity will just be able to determine what it is.
The bottom line is, 20/20 is considered to be what a person with "Normal" vision can see at 20ft. (I read a couple of sites that talked about being about to read a 20 size letter at 20 feet, but that sounds like bullshit to me). Everyone is probably familiar with Snellen's Artwork, which is known as "The Snellen Chart"
Trivia snippet:"Only the nine letters C, D, E, F, L, O, P, T, Z are used in the traditional Snellen chart"
Apparently 20/10 is extremely rare, it's almost freakish....so 20/12 is pretty damn good then. What this means is I can see an object that is 50ft away, while someone with 20/20 vision has to be 30ft away.
As you can imagine, 10 days ago I had reasonably thick glasses to correct Myopia (Nearsightedness), so I was expecting (hoping) to get 20/20 out of the LASIK zapping. To get 20/12 is beyond my wildest dreams. I am a lucky bastard, that is what.
Next time you can't quite see something, give me a call.
The most comprehensive thing about Vision Acuity I could find
A "Random Snellon" online eyetest
Buy your own Snellen chart from Amazon(you know you want to)
