It seems that you have got something wrong with onions. As you know, onions is really irritative to our eyes though they are very delicious. So, if you want to get rid of that feeling, I suggest that you try to wear a pair of glasses or something to prevent their juice. And get some normal saline to flush your eyes if you get some of it splashed into your eyes. Hope you find this useful.
As we know, it is easy for us to get the watery eyes when we cut onions because of its inner volatile stimulates. In order to prevent it, you could just put some water on the knife and then you will find that your eyes will not water when you cut the onions with the knife. This is effective and workable which you could have a try.
Here are the options for you to avoid watery eyes while cutting onions:
1.Wear a pair of goggles.
2.Put a lighting candle fire besides your chopping board.
3.Put the chopping board and the onions under water to cut.
4.Contain some water in your mouth until you finish cutting the onions.
5.Buy an onion cutter.You can leave this troublesome work to the machine.