Measuring vision in the US - Lasik Eye Surgery Message Board

Daisy139 · 02-19-2006, 02:58 PM

OK, here's a question from a European. I had LASIK done 6 weeks ago and should go to have a check up done here in the US (where I'm studying), but in the US it seems you measure vision completely differently.

Could someone explain to me what 20/20, 20/60 etc means? Where I'm from we only measure vision in dptrs. ... so I guess if I don't know what 20/20 and all that is, the check up here at the eye clinic won't tell me very much about my vision... any help?

Hating glasses · 02-20-2006, 09:19 AM

Daisy,
My understanding of 20/20 20/60 is related to distance. The first 20 is the distance the average person can see the bottom line of the eye chart at the doc's office from the chart. The second 20 or 60 or whatever the case may be is the distance that you see. So, if you are standing in front of the chart, you are 20 feet away from it. If you can see the bottom line clearly (can read it well) than you can see 20/20. However, if you can't see it clearly, whatever line you can see clearly above that (20/60) that means that the average person with better site can see the line that you can see clearly from 60 feet away. So, while you can only see that line from a distance of 20 feet away, others can see that line from a distance as far as 60 feet away from the chart. Does that make sense? I hope so! And, if I am wrong, I hope someone else will please explain it! Hehehe! I might be wrong but, that is the way I remember it being explained elsewhere!

Take care!

bowriter · 02-20-2006, 12:47 PM

I think the higher the second number, the worse the vision is. For example: 20/60: What a person with 20/20 can see at 20ft, someone with 20/60 has to move 40 feet closer to see the same line. 20/15 means that a person has extra good vision: What someone can see at 20 feet away (from the object), 20/15 people only have to walk 15 feet to see the same thing clearly. (whereas 20/20 is 5 feet closer to the object than 20/15). I believe this is how it's interpreted.

Daisy139 · 02-24-2006, 01:03 PM

Thanks for your replies, I think I kind of get it