The initial Class 1 standard is 6/6 with both eyes (the bottom line of the chart) and 6/9 in each eye separately (second from bottom I think). If you can't meet these without glasses there are limits on the refractive error of + or - 5 dioptres taking into account any astigmatism and the difference between your eyes mustn't be more than 2 dioptres (I think). The standards for a renewal are less stringent as well I think.
This is just for distance vision, there are other requirements you have to meet for near vision and peripheral vision and stuff.