I Have a Question

Classic one is my grandmother had one eye as lost one due to cancer,in Scotland she was classed blind as her good eye was like 60 percent do common sense one eye is 50 percent vision then only seeing 60 percent in that one means eyesight of sbout 30 percent total,in England they say one eye disent matter it's still 60 percent vision in that one good one,she lost out on disability money on this reason,however for driving the same government said she only had 30percent so couldn't drive so took licence