I work on the 733 and the eyelets are on the wings of my aircraft too.
A cord with a hook can be found within the frame of the overwing exits. When attached to the wing they can be used as a guide to hold onto during a evacuation after a ditching.
However, there is nothing in our ditching drill about using them. It is just one of those little extra things if time/cercumstances permit them to be used.