George - I think it is laudable that you are offering free chess instruction for kids at the library. However, these days, I would consider the librarian remiss if she allowed you to interact with children without having a 3rd-party on-hand to act as a legal chaperon. This is NOT to say you are guilty of anything. But, legally speaking, from the library's point of view, they have to be wary of adults who spend alot of time, on an informal basis, with children. If something were to happen, they may be held responsible & for that reason alone, they have little choice other than to limit you (though being banned for 'LIFE' does seem a bit extreme if you have not done anything wrong). Were it me, I think I would either acquire the appropriate state teaching credentials or teach virtually (online).
You might also contact Ferring Pharma to see if they can assist you with your prescription. 1-888-337-7464, Parsippany, NJ 07054, prosed.com.