Rob Armstrong wrote:So all you need to do to find out your level of vision is count the number of lines you can read and put a "/9" on the end - simple!
Hi Rob.
Sorry, but I think you've got the snellen scale wrong here. In my case, I can barely see the big letter at the top of the chart (line 1). According to your method that would make me "1/9", although I am variously "6/30" or "6/60".
The "6/60" means that I can see at 6 metres away what someone with normal vision can see at 60 metres. (6 metres is I think the standard distance between you and the lightbox; and the chart is resized appropriately so that everyone has a 6/xx rating).
Of course, in the USA, they don't go a bundle on metric, so they use 20/xx (feet) instead. Hence, 20/20 vision means "normal".
Also, I suppose that the snellen scale measures only what you can read, not how well you actually see it. Presumably, opticians have a different measure for that?
Any professionals out there care to give a definitive answer?