It could be a cold in the eyes or dust. Flush out the eyes and wipe them clean. Then, put a couple of drops in there for a few days.
Make sure, you look in there really good for any foreign objects/ ulcerating, just in case.
VetRx sells a goat and sheep remedy that worked well for me.
I had one young doe that had a constant runny nose and occasional watery eyes.
You can get it almost anywhere that sells goat feed, like TSC.
I think the rabbit formula is the same if you can find that instead.