If you have chickens in with your ducks and young ones who are intimidating them she very well could have gotten pecked. Have you opened the eye to look at it? I have 2 females blind in one eye one from a hawk attack the other one I have no idea. The Runner has cloudiness in her blind eye the Muscovy her eye looks normal but blind. If you can wrap her in a towel and open the eye rinse it put real good with saline then the eye drops. Put out more than one feed bowl and water buckets. I have 28 birds and I put out 4 feed bowls and buckets. I do have a Speckled Sussex who like to chase after the young Runners only them[10months] though she can't get away with it with the older girls she has never tried to scare off the drakes.