Hi Ben
Little Brothers eh .. they will play up, how old are you ? Did you tell your Mum what has happened ... I'm sure that she can help.
Betadine is an antiseptic, and it contains alcohol (not the type to drink) so although Eric got it in his eyes, you did the right thing washing it out with water straight away, however, it's best that you say something, so your Mum can make sure Eric's eyes are ok.
I hope you'll do the right thing, and tell her..
Best Wishes
Ginger