I've never had to work with a blind horse, but just from my experience with other horses I'm suggesting you use your voice a lot, and always use the same vocal cue when you are approaching, and a different vocal cue just before you touch her. That way she will not be startled. This might be a very challenging horse to keep, as she will have lost one of her senses and therefore be a risk to herself and those around her.......Im sure others here have some good tips