My eye test shows that I have 20/10 vision what does that mean?
Firstly, consider 20/20 vision because that's something many people have heard of, and sometimes mistakenly think means “perfect” vision. In reality all that 20/20 vision means is the ability to see as well as most people with healthy eyes. Specifically it means being able to read letters that are 8.7 millimetres tall from 6 metres (that's 20 feet) away, or to put it another way, to be able to perceive details that subtend an angle of 1 minute of arc. This can be considered a nice standard to achieve, something that most people can aspire to, for most of their life. Some people can do this unaided, some people will need glasses, contact lenses or surgery to get to this level. It is absolutely NOT, in any way, “perfect” vision because there is no such thing. Some people can do better than this.
So as to what 20/10 vision means, it's better. Rather than going into unnecessarily complicated explanations of how these figures are arrived at, there is a simple way to look at it. The size of the second number (the one after the /) is directly related to how big the letters on a test chart need to be for someone to read them. So while 20/20 is considered to be a good level, 20/10 is twice as good because 10 (xx/10) is only half as big as 20 (xx/20) and 20/10 therefore means being able to read much smaller letters, in fact only half as big, making 20/10 vision twice as good as 20/20.