I know my dd1's eye problems are very different to the issues other people face, but I found it helps to be very clear about whether the teasing/gawping incidents were a problem for me as a parent or for her as the child.
For example, I was very upset around the time she first got glasses, shortly after I took her to the optician and she not only couldn't read the big letters, but couldn't see that there were any letters, or a chart, for that matter -- aaargh, crap mum alert, guilt and all that. But she has always regarded her glasses as a Good Thing, because she can see with them on and can't see without them. It's that simple.
The patching, on the other hand, she really did mind about, and often in ways that I hadn't clocked straight away, like other children in the street staring. We also had problems with little old ladies coming up and asking, 'What have you done to your eye, dear?' This really floored her, because amblyopia (which is what she had) is quite complicated for an adult to explain, never mind a five-year old.
I've learnt, partly from my dd, and partly from friends whose children have much more serious eye problems that you have to dissociate your own feelings from the child's, and that however vulnerable you feel they are, you have to believe that they will have the strength to deal with it in their own way.
The final word to my dd (then aged 6), who came home and complained about some girls in the year above teasing her about her glasses.
Me: (rolling up my sleeves to go and beat the whatnots out of the little toads): What did you say when she called you four-eyes?
DD: I told her she's in the year above me, so she should know better.
Way to go, sister.