What can I do to make sure my eye stays locked on object ball until it drops in pocket?

You need to change your habit.  It's a hard thing to do if you've been doing something a certain way for a long time.  I used to almost always use an open bridge.  I'd been doing it for a long time.  I tried using a closed bridge and I actually liked it better.  But it took me a long time to make sure I was using an open bridge all the time.  I had to break my bad habits.  Some people use open bridges almost all the time.  But my two favorite pool players, Efren Reyes and Earl Strickland almost always use closed bridges.